Equine Reproduction & Stud Medicine: Self-Assessment Colour Review 1874545448, 9781874545446

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Self-Assessment Colour Review of

Equine Reproduction and Stud Medicine Jonathan F. Pycock BVetMed, PhD, DESM, MRCVS University of Utrecht, The Netherlands

Manson Publishing/The Veterinary Press

Copyright © 1997 Manson Publishing Ltd ISBN: 1-874545-44-8 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the written permission of the copyright holder or in accordance with the provisions of the Copyright Act 1956 (as amended), or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 33–34 Alfred Place, London WC1E 7DP. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. A CIP catalogue record for this book is available from the British Library. For full details of all Manson Publishing Ltd titles please write to: Manson Publishing Ltd, 73 Corringham Road, London NW11 7DL, UK. Typeset and designed by: Paul Bennett Colour reproduction: Tenon & Polert Colour Scanning Ltd, Hong Kong Printed by: Grafos SA, Barcelona, Spain

Foreword Although you might assume from the title that this is simply a self-quiz book, upon reading it you will find it to be much more. This is not a book that will be read once in preparation for examinations and then put on the shelf. With the inclusion of a broad classification of cases (page 7) and an index (page 201), this text becomes an excellent reference source. The text includes over 200 challenging questions written by an internationally renowned group of experts in their respective fields. The questions are clinically oriented and cover a broad range of important subjects. The accompanying photographs are of excellent quality, clearly showing the problem being addressed, and make this book an invaluable source of information for students and teachers alike. The layout of the book is very user friendly. The answers are found on the page following the question, which removes the frustration of having to search elsewhere in the book to find the answer. Randomisation of the topics makes the book interesting to read and stimulating. The format lends itself to reading at an extended sitting or in small bites. The coverage is up to date and uses material from recent publications. The answers are clear and concise, and deal with practical aspects of diagnosis and treatment. The editor, himself a well-known authority in the field, has taken care to provide a well-balanced text covering all areas of stud medicine, without overemphasising any particular aspect. The cases chosen do not focus on topics unique to any one geographical area – they cover problems confronting veterinary practitioners everywhere and so are applicable world wide. This informative text will be a welcome addition to the equine practitioner’s library and will also prove invaluable to anyone preparing for speciality examinations and for veterinary students with an interest in equine theriogenology and perinatology. Dale L. Paccamonti DVM, MS, Diplomate ACT Louisiana State University, Baton Rouge, Louisiana, USA

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Preface Recent developments in equine reproduction have meant that extra information needs to be assimilated by practising and student veterinarians and breeders. Whilst there are many excellent texts that provide detailed information on the subject, the aim of this project was to provide a series of case scenarios any of which could face us in our daily work: the mare that will not become pregnant, the foal that is sick or the stallion whose semen needs to be evaluated. The information given in the answer is sufficient that the book should not only be helpful to practitioners, but also to veterinary students preparing to graduate. These detailed answers should hopefully ensure that the book can be returned to on several occasions and additional information retained each time. With the now almost routine use of ultrasound in mare gynaecology, improved standards of foal care and the growing importance of artificial insemination, it was imperative that a broad-spectrum of questions was chosen. To ensure that all the important problems were covered, some twenty-two contributing authors were selected from several countries. And to make certain a practical approach was taken, the authors were all people directly involved in the subject, facing essentially the same problems as could be encountered by any one of us on any day. Although seemingly fairly simple, the enormity of the task was far greater than expected. Nevertheless, I hope and believe that what has finally been achieved is an excellent selection of cases. This is due largely to the superb standard of photographs, questions and answers from all the contributors. Inevitably in a book of this nature the answers may not be universally accepted as the only correct possibility: have you ever tried writing an answer on how to approach and treat a case of retained placenta that would please every veterinarian? Undaunted I offer up the questions for discussion, debate and, hopefully, education. There is nothing quite like the sight of a newborn foal and I hope this book proves to be helpful to all of us fortunate to work with that most noble of animals, the horse. Jonathan F. Pycock 1997

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Acknowledgements I should like to thank all the contributors for submitting such a wide range of practical and clinically important cases. The book could easily have been twice the size, and the assembly of all the cases into the final end product took far longer than anticipated, partly due to the huge volume of material. Those mentioned below contributed photographs for use in the book: Dr T.J. Divers, University of Cornell, USA Dr D.C. Knottenbelt, University of Liverpool, UK Dr H. van der Kolk, University of Utrecht, The Netherlands Dr J. Lofstedt, Atlantic Veterinary College, Canada Dr P Taylor, University of Cambridge, UK Dr P. Timoney, University of Kentucky, USA Many colleagues in the Department of Herd Health and Reproduction at the University of Utrecht provided support and encouragement, particularly Bert van der Weijden and Herman Jonker. Arie Hofman and Wim Bes provided excellent photographic and artwork skills respectively. Finally, I should like to thank my wife, Gill, for her continued patience and understanding and my daughter, Sara, for being here. I dedicate this book to them both.

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Contributors Annalisa Barrelet, BVetMed, MS, CertESM, MRCVS Rossdale & Partners, Newmarket, Suffolk, UK

Celia Marr, BVMS, MVM, PhD, MRCVS Valley Equine Hospital, Lambourne, Berkshire, UK

Tim Brazil, BVSc, CertEM (Int. Med.), MRCVS University of Liverpool, Neston, Merseyside, UK

Graham Munroe, BVSc, PhD, DESM, CertEO, FRCVS University of Edinburgh, Midlothian, UK

Ben Colenbrander, DVM, PhD University of Utrecht, Utrecht, The Netherlands Chrysann Collatos, VMD, PhD, Diplomate ACVIM High Desert Veterinary Service, Reno, Nevada, USA David Dugdale, MAVetMB, CertEP, CertESM, MRCVS Greenwood, Ellis & Partners, Newmarket, Suffolk, UK

John R. Newcombe, BVetMed, MRCVS Newcombe and East, Brownhills, West Midlands, UK Joyce M. Parlevliet, DVM Specialist in Equine Reproduction, University of Utrecht, Utrecht, The Netherlands Reginald R. Pascoe, BVSc, MVSc, DVSc, FRCVS, FACVSc Oakey Veterinary Hospital, Oakey, Queensland, Australia

David Ellis, BVetMed, DED, FRCVS Specialist in Equine Surgery, Greenwood, Ellis & Partners, Newmarket, Suffolk, UK

Jonathan F. Pycock, BVetMed, PhD, DESM, MRCVS Specialist in Equine Reproduction, University of Utrecht, Utrecht, The Netherlands

Gary C.W. England, BVetMed, PhD, CertVA, DVR, DVReprod., Diplomate ACT, FRCVS University of London, Hertfordshire, UK

Virginia B. Reef, DVM, Diplomate ACVIM (Int. Med.) George D. Widener Hospital, Pennsylvania, USA

G. Mark Johnston, MA, VetMB, MRCVS University of Cambridge, Cambridge, UK

Marinus A. van der Velden, DVM, PhD University of Utrecht, Utrecht, The Netherlands

F. Herman Jonker, DVM, PhD Specialist in Equine Reproduction, University of Utrecht, Utrecht, The Netherlands Guy D. Lester, BVMS, PhD, Diplomate ACVIM University of Florida, Gainesville, Florida, USA Deborah M. Lucas, BSc, MSc, CBiol, MIBiol Eastleigh, Hampshire, UK

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Paul J. de Vries, DVM Specialist in Equine Reproduction, Vierhouten Equine Clinic, Heerde, The Netherlands Gysbert C. van der Weijden, DVM, PhD University of Utrecht, Utrecht, The Netherlands Katherine Whitwell, BVSc, FRCVS Specialist in Veterinary Pathology (Equine), Newmarket, Suffolk, UK

Broad classification of cases Mare Abortion: 10, 25, 32, 39, 126, 133, 192, 200, 217 Anatomy: 13, 14, 36, 46, 57, 64, 69, 83, 90, 92, 104, 116, 128, 157, 165, 175 Breeding management: 11, 26, 60, 99, 111, 118, 130, 134, 168, 190, 201 Internal medicine: 24, 44, 88, 138, 186, 191 Parturition: 17, 22, 52, 62, 67, 75, 94, 125, 129, 140, 145, 148, 163, 171, 179, 193, 205, 217 Pregnancy: 15, 76, 85, 141, 144, 151, 156, 194, 198, 199, 213 Surgery: 19, 41, 57, 62, 63, 85, 109, 149, 162, 180, 195 Ultrasonography: 2, 12, 20, 27, 34, 41, 42, 47, 53, 55, 61, 65, 72, 77, 84, 91, 98, 105, 113, 120, 127, 135, 154, 160, 167, 174, 182, 189, 196, 203, 209

Foal Internal medicine: 18, 31, 35, 38, 48, 51, 54, 66, 68, 73, 80, 81, 82, 93, 103, 115, 117, 132, 136, 146, 152, 153, 158, 170, 173, 176, 177, 178, 197, 210, 212, 215 Non-orthopaedic surgery: 1, 29, 71, 86, 121, 123, 206 Opthalmology: 5, 33, 101, 131, 155, 159, 164, 181, 183 Orthopaedics: 4, 6, 16, 21, 30, 58, 79, 89, 95, 96, 102, 114, 119, 124, 139, 143, 147, 166, 202, 211 Ultrasonography: 29, 56, 100, 107, 123, 169, 187, 204, 207, 214

Stallion AI, semen collection/evaluation: 3, 37, 43, 50, 74, 78, 87, 97, 106, 150, 161, 184, 185, 188 Breeding management: 7, 8, 23, 108, 137 Surgery: 9, 28, 40, 49, 59, 110, 112, 122, 142, 172, 208

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Abbreviations AI AV CBC CEMO CL CSF DIC DOD DSO eCG EIA ELISA EHV EVA GI GnRH GTCT H&E hCG HIE IM IP IU IV NI NMS NSAIDs PCV PDA PMNs PPM RBCs RM SCID TPR VSD WBCs

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artificial insemination artificial vagina complete blood count contagious equine metritis organism corpus luteum cerebrospinal fluid disseminated intravascular coagulation developmental orthopaedic disease daily sperm output equine chorionic gonadotrophin equine infectious anaemia enzyme-linked immunosorbent assay equine herpes virus equine viral arteritis gastrointestinal gonadotrophin releasing hormone granulosa-theca cell tumour haematoxylin and eosin human chorionic gonadotrophin hypoxic ischaemic encephalomyelopathy intramuscular immunoperoxidase international units intravenous neonatal isoerythrolysis neonatal maladjustment syndrome non-steroidal anti-inflammatory drugs packed cell volume (haematocrit) patent ductus arteriosus polymorphonuclear leucocytes posterior pupillary membrane red blood cells retained meconium severe combined immunodeficiency syndrome temperature, pulse and respiration ventricular septal defect white blood cells

1, 2: Questions 1 A weanling foal is presented with a soft fluctuant swelling on the cranio-lateral aspect of the base of the right ear (1a) This has been present since birth. i What is your diagnosis? ii What is the treatment?

1a

2a

2b

2 An oestrous mare was mated on three occasions at 2-day intervals early in the breeding season. When teased 2 days after her last covering date, she appeared to be no longer in oestrus. Fourteen days later she was presented for pregnancy diagnosis and the results of ultrasound examination of the left ovary (the right ovary was similar) and the uterus are shown (2a, b). i What are the ultrasonographic features of the left ovary and the uterus? ii If the mare was teased before examination for pregnancy, would you expect oestrous signs? iii How would you expect the cervix to feel on palpation? iv What two possible series of events could have resulted in these findings? v If the mare had been examined 3 days earlier and a similar picture found, what is a possible explanation?

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1, 2: Answers 1b

1 i A dentigerous cyst. This congenital malformation is relatively uncommon and can vary in size. Some cases have little more than small openings on the medial margin of the pinna from which a waxy or honey-like discharge emerges. ii They only cause trouble if they become very large or discharge profusely. They are generally removed for cosmetic reasons. Under general anaesthesia the cyst tract is dissected away from the overlying skin and followed down towards the petrous temporal bone. This is facilitated by inserting a probe and at the base of the tract or cyst a vestigial tooth or bony remnant is normally found and this should be removed using rongeurs (1b). Subcuticular sutures eliminate dead space and the skin is then closed with simple interrupted sutures. Even after the removal of very large cysts healing is good. 2 i The left ovary has three follicles of approximately 2 cm in diameter. No obvious echoic area which could represent a CL is visible. The characteristic alternating and intertwining hyperechoic and hypoechoic areas due to uterine oedema are seen, which are characteristic of the mare being in oestrus. There may even be a small amount of free luminal fluid in the centre of the image. The uterus of the mare is somewhat T-shaped and so the uterine horns are generally imaged in cross-section whereas the body appears rectangular. This image appears circular and so is likely to be of the uterine horn. ii Yes. Since there is uterine oedema and no obvious CL, one would expect (but not be guaranteed) signs of oestrus. iii Soft and relaxed. iv (1) Early in the breeding season, it is possible that the mare is in the transitional phase before the first ovulation of the year. During this time of year, the mare demonstrates erratic oestrous behaviour and it is possible that she did not ovulate as assumed at the time she went out of oestrus. The large follicle may have regressed and 15 days later the mare will probably be back in oestrus. (2) The mare ovulated on or about the time of the last mating and, having failed to become pregnant, is returning to oestrus on day 16 or 17. v Following ovulation on or about the last mating date, the mare suffered a postmating bacterial endometritis severe enough to cause premature regression of the CL and is now returning to oestrus early.

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3–5: Questions 3 i What are the advantages of an AI programme? ii What is the procedure for insemination of a mare?

4 A 3-week-old foal was found to have soft swellings over the dorsolateral aspects of both carpi (4). The foal was not lame but resented firm flexion of both carpi. i What is your diagnosis? ii What treatment do you recommend? iii What is your prognosis?

4

5 i What is the abnormality in this 18-hour-old Thoroughbred foal (5)? ii What is your therapy for this foal?

5

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3–5: Answers 3 i (1) AI can be an effective means to control sexually transmittable diseases. (2) More mares can be inseminated from one ejaculate, which means that a stallion can breed more mares per year. (3) Transport of semen across or even between countries is possible. (4) In addition to being able to keep a mare (and young foal) at home, the risks of infections are reduced as are risks from transport. (5) Risk of injury from mating is eliminated. (6) Since semen from a stallion in an AI programme will be evaluated more often, any problems in his fertility will be identified more quickly. Regulations prescribe how to keep stallions used in an AI programme and the control of diseases to guarantee the export of healthy semen. ii Ideally, the mare should be restrained in stocks, her tail bandaged and tied to one side. Her perineal area must be thoroughly cleaned, ensuring that no dirt remains immediately inside the vulval lips. The inseminator puts on a sterile or ‘inside-out’ plastic rectal glove and covers the tip of the insemination pipette. As small amount as possible of non-spermicidal lubricant is placed on the back of the glove and the finger is used to identify the external os of the cervix. The insemination pipette is advanced through the cervix into the uterine body and the spermatozoa slowly deposited. All equipment used for the insemination process (syringes, etc) should be nonspermicidal. 4 i This foal is showing bilateral rupture of the common digital extensor tendons. The condition may be unilateral or bilateral and, depending on the amount of synovial fluid accumulated, the ruptured ends of the tendons may be palpable. It occurs most frequently in neonatal foals and especially in those with some flexural deformity of the distal limb and carpal joints. Some cases will start to knuckle over following rupture. ii The foal should be confined to a stable for 2–4 weeks which will allow the tendon to heal by fibrosis. Casting the forelegs has been suggested, but this is only necessary if the foal persistently knuckles over as casting can lead to the development of pressure sores. The swelling of the tendon sheaths can take some months to disappear. iii The prognosis for full soundness is usually good, particularly if flexural deformity is absent or mild. 5 i Entropion. This condition occurs commonly in newborn foals and is not likely to represent a permanent problem, but must be addressed in order to prevent corneal ulceration which can become a severe complication in sick neonatal foals. ii In some foals the entropion is exacerbated through dehydration and will resolve with rehydration and manual eversion of the lid. Injection into the eyelid with procaine penicillin G can be very effective in those foals where hydration failed to improve the condition. An alternative and superior method for moderate entropion is to use mattress sutures in the lid. Surgery is rarely, if ever necessary. Fluorescein staining of the cornea is recommended on a daily basis in very sick foals in order to detect ulceration. Unlike adult horses, foals with corneal ulcers often lack blepharospasm and excessive lacrimation and therefore ulcers can frequently go unnoticed until severe.

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6–8: Questions 6 A 3-week-old foal was found to have a slight distension of a front fetlock joint. The foal was not lame but it resented firm flexion of the fetlock joint. The mare and foal had recently been confined to the stable for 2 days. A radiograph of the affected joint is shown (6). i What lesion is present? ii How has this occurred? iii What is the prognosis and treatment required?

6

7 The penis of a stallion used for natural breeding is shown (7). i What is your diagnosis? ii What treatment would you advise? iii How would you control the disease?

7

8 A 9-year-old gelding shows stallion-like behaviour in the presence of mares either at pasture or at a competition. i What are your possible diagnoses? ii How would you diagnose the condition? iii Assuming a positive result to the test you describe in ii, what advice would you give to your client?

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6–8: Answers 6 i A distracted basal fracture of one of the proximal sesamoid bones. ii Fractures of the proximal sesamoid bones are not uncommon in young Thoroughbred foals under 2 months of age. These fractures may involve one or more sesamoid bones, usually affect the front legs and appear to be the result of the foal galloping to exhaustion in an attempt to keep up with the dam or other foals. This seems to be a particular problem if the mare and foal have been confined for illness or angular limb deformity in the foal and then are turned out into a large paddock with other mares and foals. It is always wise to check or radiograph the other fetlock joints. iii The prognosis for a fractured sesamoid bone in a young foal is good provided healing is accompanied by minimal changes in the shape of the bone. Such is the case with chip, fissure or simple apical or basal fractures without displacement of the bony fragments. Rest and bandage support of the fetlock is a satisfactory method of treatment in these cases. When there is displacement of the fracture, as in this case, fibrous union ensues and the prognosis as an athlete is poorer. In these cases, surgical removal of the fragment is the treatment of choice, again followed by a prolonged period of box rest. 7 i Equine coital exanthema caused by EHV-3. The virus causes vesicles to appear on the shaft of the penis and prepuce of the stallion. When these rupture, ulcerated areas are left and infectious material may be spread. The ulcers usually heal rapidly without complications, leaving depigmented areas. ii Immediate sexual rest for up to 3 weeks to allow healing of the lesions and prevent further spread. Further treatment is often not necessary, although topical antibiotic ointment can be used to prevent secondary bacterial infection following cleansing of the lesions. The stallion’s penis may be washed with a very mild solution of disinfectant (2% chlorhexidine) for 3 consecutive days. iii Coital exanthema is a venereal disease and outbreaks are usually sporadic, with the initial cause difficult to identify. Control is by hygienic working and careful inspection and withholding mating of affected horses and appropriate hygiene precautions when handling affected animals. AI provides a means of control. 8 i Stallion-like behaviour in a gelding can be a behavioural/neurological problem. More likely the gelding is, in fact, a cryptorchid. Most likely he is a bilateral cryptorchid, but it is possible that only one testicle was removed at the time of castration. ii Palpation of the inguinal ring or rectal palpation may not give a reliable diagnosis, unless a testicle can be found. To diagnose the condition, a stimulation test usually involving injection of hCG is used. In most cases, 6,000–12,000 IU hCG is used to stimulate the testicles. Before treatment with the hCG, heparinised blood samples are taken for determination of basal testosterone and conjugated oestrogen (or oestrone sulphate) concentrations. In a cryptorchid horse, the basal testosterone and conjugated oestrogen concentrations are higher than in normal geldings. One hour after IV injection of the hCG, a second heparinised sample is taken in which the concentration of testosterone is measured. In cryptorchid stallions, there is a rise in testosterone concentration. This method has a high accuracy in detection of a cryptorchid. For horses over 3 years old, it may only be necessary to measure oestrone sulphate in a single sample. iii Surgical removal of the testis.

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9, 10: Questions 9 i Which method of castration is demonstrated (9a, b)? ii What is the aim of using this method? iii What are the disadvantages of this method as compared with techniques in which the scrotal wounds are not closed by suturing?

9a

9b

10 An owner finds that one of a group of six pregnant mares has aborted in the paddock. The owner is annoyed at the financial loss caused by the abortion and is reluctant to take any action, other than check the mare and bury the fetus. i What steps should be taken in the short term? ii What is the main benefit in having the abortion investigated? iii Apart from screening for contagious agents, what other advantages are there for the owner to have the abortion investigated? iv What are the two main options to carry out such an investigation?

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9, 10: Answers 9 i The primary closure method, in which following open castration the scrotal incisions are closed in three separate layers: the vaginal tunic, tunica dartos and skin. ii To achieve healing by primary intention of the scrotal incisions, which shortens the period of healing and convalescence, and rules out complications that may occur during healing by second intention, such as excessive oedema, infection, pain and stiffness. iii This method requires more surgical and anaesthetic time, and a far higher degree of surgical cleanliness. As there remains an open inguinal canal, post-operative inguinal herniation can occur, however low the incidence of this complication may be. 10 i The mare should be placed in strict isolation and be allocated an attendant with no contact with other pregnant mares. The fetus and membranes should be placed in a leakproof container and submitted for post-mortem examination and sampling. The site where the abortion occurred should be disinfected. Movement of horses off the stud should be stopped and any owners about to send mares to the property should be notified of the situation. Subsequent actions depend upon the outcome of laboratory tests. ii To confirm or to exclude the presence of an infectious agent as the cause of the abortion. If a contagious abortion was to be confirmed, stringent management procedures would be needed to try and prevent spread to other horses, particularly pregnant mares. Failure to identify a contagious abortion could lead to considerable financial loss to the owner and to the owners of contact animals on other premises. iii Knowledge of the cause of an abortion can influence the immediate veterinary treatments given, e.g.infective placentitis is likely to be accompanied by a localised deep-seated infection of the endometrium. Determination of the organisms causing the placentitis and their antibacterial sensitivities will assist in selection of the optimal treatment of the mare: for foals born alive prophylactic antibacterials can be given. Some mares may be prone to abort again for the same reason and when a cause is identified positive steps can be taken to prevent this, e.g. mares with placentitis, twin pregnancy. Some mares have other forms of uterine disease capable of causing repeat abortion or infertility, and which can be suspected following inspection of the placenta, e.g. severe uterine scarring and congenital uterine anomalies. This information will assist the owner in planning the future breeding policy for the mare. iv Infection in a fetus or neonatal foal can only be diagnosed by laboratory examination of selected tissues (for EHV-l, histopathology and/or virus isolation; for EVA, virus isolation; for leptospirosis, histopathology). The options for the attending veterinary surgeon are either: (1) transport the abortion to a suitable site, carry out an autopsy taking tissues into both fixative and virus transport medium, and then forward the samples with a full clinical history to a specialist laboratory for evaluation. The autopsy should include a close general inspection of the fetus and its membranes, and bacteriological sampling as appropriate. Or (2) forward the whole fetus and placenta plus history directly to a suitable laboratory for a full evaluation.

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11, 12: Questions 11 Mares and foals return to their home stud farm. The mares are in foal, and the foals at foot are 2–4 months old. The home stud has an abundance of grass, and the stud management does not intend to provide any supplementary feed to either mares or foals until weaning due to concern about overtopping the foals and the mares becoming obese. i Do you consider the pasture alone would be satisfactory for the mares and foals? ii What minerals are the most likely to be deficient? iii What amino acid is likely to be deficient? iv What feeding arrangements would you recommend in the stud farm situation?

12a

12b

12 You are asked to examine a broodmare for pregnancy bred by natural mating 17 and 15 days earlier. When teased 2 days after the last mating she was apparently no longer in oestrus. The ultrasound images show the left ovary (12a), the right ovary (12b) and the left uterine horn (12c) at the examination for pregnancy. i How would you describe the findings in the right ovary? ii What is shown in the uterus? iii What three possible series of events could have resulted in the findings?

12c

17

11, 12: Answers 11 i The pasture alone will probably provide adequate (or even excessive) energy, crude protein and fibre levels to meet the requirements of a mare in later lactation, and a 3-month-old foal. However, the mineral and amino acid levels in most pastures may not meet the requirements of either the mare or the foal. The growth rates and demands particularly upon Thoroughbred and Warmblood youngstock and broodmares results in increased requirements over and above those provided by mares’ milk and pasture alone. The mare and foal should receive additional minerals and amino acids on a daily basis to meet the shortfall of these nutrients from the pasture. It is important that the mare and foal do not become obese and the method selected to provide additional minerals and amino acids should not provide significant additional energy or crude protein. ii Copper, zinc and sodium, with calcium, magnesium, selenium and manganese likely to be marginal. iii Lysine. This is thought to be the first limiting amino acid in horses. iv Separate feeding arrangements for mares and foals ensure that the foals receive a known intake. 12 i A uniformly echoic CL. Although not as readily identifiable as in the first few days following ovulation, the CL is generally able to be detected for around 17 days following ovulation. ii The uterus illustrates a spherical structure some 8 mm in diameter. Specular reflections can be seen as white stripes at the top and bottom of the anechoic sphere. These are not diagnostic of pregnancy but are often found in the early pregnancy, and this image (due to its perfectly spherical shape) is highly suggestive of an early conceptus. iii (1) If the mare ovulated 12 days earlier, then the vesicle is within the normal size for age range. However, ovulation so recently would seem unlikely as the mare had stopped showing oestrous behaviour 13 days earlier. (2) If the mare had ovulated as would be expected from the reported oestrous behaviour (between 14 and 16 days earlier), then the vesicle is ‘small for age’. It is highly probable that the pregnancy, with an abnormally small vesicle, will fail. (3) Although the mare may well have ovulated between 14 and 16 days ago and was, therefore, going out of oestrus when teased 13 days earlier, a second ovulation could have occurred a day or so after this last teasing date. The last mating 15 days earlier could have failed to produce a vesicle from the first ovulation, but semen could have survived long enough to fertilise the oocyte from the second ovulation. In this case, the vesicle is normal for a day 12 pregnancy. Accurate examination of the ovaries in this situation should reveal the presence of two CLs, although they can be somewhat indistinct at this stage.

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13–15: Questions 13 A 12-year-old multiparous barren mare failed to become pregnant the previous breeding season (13). Examination of the genital tract reveals a mature follicle present, an open cervix and a slightly distended uterus which, on palpation, expresses air out through the vulvar lips. Speculum examination revealed a reddened and relaxed cervix with air bubbles intermixed in a clear thin watery discharge. i What clinical conditions may exist? ii What physical changes might be detected on clinical examination which indicate a possible cause of the infertility? iii Do you regard this mare’s vulva conformation to be a contributing factor to her infertility? iv What importance is attached to the level of the pelvic brim in relation to the vulva?

13

14 An endometrial biopsy specimen stained with H&E taken from a mare in oestrus (14). There is a cellular infiltration within the superficial stroma. i What cell types can you identify in the infiltration? ii What is the significance of each type of cell you listed? iii What treatment would you recommend?

14

15 The figure shows a laboratory test for eCG (15). i What type of test is this? ii Which test area (1 or 2) shows the positive result? iii At what stage of gestation is the test useful for pregnancy diagnosis in the mare? iv What sample is needed? v Under which circumstances could a false-positive result be obtained?

15

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13–15: Answers 13 i Acute and chronic endometritis, pneumovagina, urine pooling and an incompetent cervix. ii (1) Poor conformation of the vulva and anus; (2) the presence of air bubbles in the vaginal and/or uterine mucous indicates the possibility of pneumovagina; (3) careful manual exploration may indicate injury to the cervix; (4) ballooning of the anterior vagina may indicate both pneumovagina or urine pooling; (5) palpation and speculum examination to determine the location of the urethral opening and of downward displacement of the cervix and anterior vagina anterior to the pelvic brim. iii Yes. iv The high level of the pelvic brim in relation to the vulva maintains an almost vertical vulva. A low pelvic brim may cause the vulva to tend to a horizontal position. 14 i PMNs, mononuclear cells (histiocytes) and eosinophils. ii PMNs indicate acute endometritis, typically as a result of bacterial infection. The mononuclear cells indicate local antigenic stimulation or chronic infiltrative endometritis, and the presence of eosinophils is thought to be associated with pneumovagina/pneumo-uterus. iii The acute endometritis should be treated with a course of antibiotic irrigations according to sensitivity results performed on significant organisms cultured from the uterus. A soluble, non-residue forming, non-irritant, broad-spectrum, intra-uterine antibiotic combination should be chosen. The chronic infiltrative endometritis does not require specific treatment. Eosinophils suggest that pneumovagina may be a predisposing factor in the development of acute endometritis, and the perineal architecture should be carefully assessed and appropriate vulval surgery performed as required. 15 i Slide agglutination test. ii Test area 1 shows agglutination indicating a positive result. iii 45–95 days gestation is the window in which reliable results are usually obtained. The hormone is produced by the endometrial cups starting at around 35–40 days and the cups are destroyed by an immunological reaction by about 130 days gestation. iv A serum sample. v If the pregnancy is lost after the endometrial cups have been formed, the eCG profile will be the same as in a pregnant mare.

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16–18: Questions 16 This tarsal radiograph is taken from a newborn foal that was born at 309 days gestation (16). i What is the abnormality? ii What advice would you give to the foal’s owners?

16

17 One of the three stages of normal spontaneous equine parturition (17). i What stage is this? ii Under normal undisturbed circumstances, this stage of parturition should not exceed how many minutes? iii What are the three stages of parturition and what are the principal characteristics of each?

17

18 This 72-hour-old male quarter horse foal (18) was examined because the owner felt that it was continuously straining to defaecate, although an enema had been given shortly after birth and some meconium was observed in the stall the following morning. Characterise the foal’s posture.

18

21

16–18: Answers 16 i The radiograph demonstrates inadequate tarsal bone ossification. Although there is a suggestion of developing tarsal bone collapse it is too early to be confident of this diagnosis. Note that developing bones often have a blurred margin that is sometimes interpreted as osteomyelitis. ii There is a potential dilemma with this foal. Limited exercise would be beneficial for improving any tendon laxity, commonly seen in dysmature or premature foals. Forced recumbency could impact negatively on a pulmonary system that has failed to mature adequately prior to birth. In contrast, unrestricted exercise could result in permanent cartilage damage and abnormal bony ossification. Most agree that limited exercise, possibly combined with limb splinting, would be the most prudent advice to offer. The bones should be radiographed weekly in order to follow ossification. 17 i Stage 2, during which the actual delivery of the foal takes place. Note the forelimbs enclosed within the bluish-white amnion. ii Thirty minutes; only very rarely will it normally exceed 1 hour. On average, this stage takes some 17 minutes. iii Stage 1: increasing myometrial activity which, together with spontaneous fetal movements, will result in rotation of the cranial part of the fetal body into a dorsosacral position. The front legs and head are extended. Increased uterine activity will also result in dilation of the softened cervix. These processes usually result in discomfort which is demonstrated by restlessness (tail switching, frequently lying down and getting up) and signs of abdominal pain. Patchy sweating (flanks, neck, behind elbows) and yawning/flehmen are other external signs of this stage. Rupture of the allantochorionic membrane and the escape of the allantoic fluid indicates the end of this first stage. This stage may last one to several hours. Stage 2: obvious, occasionally forceful, abdominal straining marks the beginning of this period during which expulsion of the fetus occurs. As the amnion emerges at the vulva, one foreleg becomes visible, usually preceding the other foreleg by some 10 cm. The foal has a relatively long umbilical cord which is still intact after delivery. The cord usually ruptures at a predetermined place due to movements of the mare and/or foal several minutes (up to 15 minutes) after birth. Stage 3: expulsion of the placenta, which takes approximately 1 hour on average. Continuing myometrial activity plays an important role during this process. 18 The arched back, raised tail head and stretched stance are more consistent with urination than defaecation posture, although foals may manifest abdominal pain by adopting a urination posture.

22

19, 20: Questions 19 A 10-year-old multiparous Standardbred mare which had been ‘caslicked’ the previous breeding season, foaled unexpectedly and unattended. The mare has expelled the placenta, the foal is normal and sucking well. The mare had a serious 2nd degree perineal laceration when examined 12 hours after parturition. i When would you repair this? ii How would you repair this tear?

19

20a

20b

20 You are asked to examine a broodmare for pregnancy that was bred 17 and 15 days earlier. When teased two days after the last mating she was apparently no longer in oestrus. Ultrasound images show the left ovary (20a), the right ovary (20b) and the left uterine horn (20c). What are the findings and what is a logical explanation?

20c

23

19, 20: Answers 19 i Where bruising is minimal, a full repair can be carried out immediately to prevent pneumovagina. Where bruising is more extensive, a temporary repair should be carried out to minimise uterine infection and pneumovagina. ii (1) A careful examination of the area should be made to assess that no cervical damage has occurred; that the rectal mucosa is intact and whether the extent, amount of bruising, future contamination and/or infection may delay primary healing if a repair is effected. Should bruising be too extensive, then repair should be delayed for 7–10 days, or if the degree of injury is severe, the wound may need to granulate before repair. This is governed by the degree of angulation of the vulva and pneumovagina which may develop in the interim, in which case, the repair should be effected even though the eventual outcome may need a second repair. This should be made clear to the owner/stud manager. If assessment indicates a poor immediate surgical risk, surgery should be postponed for 7–10 days. However the external view as shown would indicate the likelihood that there is minimal trauma and an immediate repair could be contemplated. (2) Repair procedure: tranquillise the mare after placing her in the stalls, preferably, or over the stable door or several bales of hay (less satisfactory). Where a 2nd degree tear is extensive, an epidural or local infiltration to the full depth of the tear can be used. Thoroughly clean and surgically prepare the surgical area. Surgically debride all severely bruised tissues, tissue strands which will be non-viable and tie off any new points of haemorrhage. Wherever possible, freshen tissues slightly to ensure all bruised tissues are removed before suturing. Repair can be made using single deep vertical mattress sutures of synthetic monofilament suture material. These sutures should be placed to close the injured area, bring the vaginal mucosa back into apposition and close the dead space between the vagina and skin tear. A continuous lock stitch can then be used as a skin suture; if there is a risk of dehiscence, then single interrupted skin sutures would be preferable. 20 The mare appears to be pregnant. The diameter of the vesicle suggests a pregnancy of at least 15 days. It is possible that the mare ovulated a day before the teasing 15 days earlier but remained in good oestrus. Ultrasonographic examination of the ovaries, however, reveals no apparent CL, which normally loses its ability to be readily detected ultrasonically by day 15 or 16 in the cyclic mare. If the ‘embryonic vesicle’ is inspected closely, its shape is somewhat irregular. Embryonic vesicles vary considerably in diameter by day 15 (14–22 mm) or day 16 (20–28 mm) (day 0 is day of ovulation). However, they usually retain their circular to ovoid shape and regular outline until about day 17 or 18. From the date of the last known day of oestrus, it is highly unlikely that the pregnancy is more than 16 days. In addition, there is some oedema apparent in the uterus. This can be found on occasions in pregnant mares, and is normally localised and transient around day 16 to day 18 of pregnancy. An earlier ultrasound examination of the uterus would have answered the question as to whether the structure was indeed a cyst, but in view of the shape and size of the vesicle and the absence of an ultrasonically detectable CL, the structure is more likely to be an endometrial cyst.

24

21–23: Questions 21

21 A 3-week-old foal was found severely lame in its stable with swelling over the left carpus. Flexion of the carpus was resented. Radiographs were taken of the carpus (21). i What is your diagnosis? ii How should you treat the injury?

22

22 A parturient mare is presented to you in the condition shown (22). The foal has been in this position for 25 minutes. On physical examination, the foal is dead. i What is this condition? ii How would you treat the animal?

23 Clinical examination of the scrotum of a young stallion revealed the signs in 23 (posterior view). No other abnormal clinical signs were detected. i What is your diagnosis and treatment? ii What comments do you have on this condition and the advisability of standing the stallion at stud?

23

25

21–23: Answers 21 i A comminuted fracture of the ulnar carpal bone. ii This injury was treated by external fixation. Under general anaesthesia, the foal was placed in lateral recumbency and a full-length cast applied up to the elbow The leg was dusted with boric acid and a double layer of stockingette was rolled on to it from the foot to the elbow. A cast was applied from the foot to the elbow taking care to pad the upper limit of the cast. The toe region was reinforced with several slabs of the casting material and the heel built up by 1–2 cm. The cast was removed after 6 weeks by which time bony healing was progressing satisfactorily. No angular deviation was evident. Despite careful attention to padding, a pressure sore may develop. This should be treated as an open wound and usually heals satisfactorily. The foal was confined to a stable for a further 6 weeks, after which time it was allowed access to a small paddock. Internal fixation can be carried out if there is a simple fracture. However, if there is any comminution, as in this case, internal fixation may result in further fragmentation. 22 i As the head and the neck have already extruded for a great deal from the vulva, the most likely condition is a bilateral shoulder flexion posture. With bilateral carpal flexion, the head and the neck cannot be advanced so far. ii Only under very rare circumstances can a foal in this abnormal posture be delivered by traction. Retropulsion of a foal already advanced that far is very difficult or impossible. In this case, an immediate partial fetotomy is the best treatment. When the mare can be kept in stocks a fetotomy in standing position is preferable. After caudal epidural anaesthesia and thorough cleaning of the area, extravulval removal of the head and neck are quickly performed by means of a fetotome. After adequate lubrication, this is followed by retropulsion of the fetus in order to diminish the straining reflex and to make room for further partial fetotomy, which includes removal of one or both forelimbs. Initially, an incision is made in the skin and muscles between the dorsal part of the scapula and the thorax. Then the fetotomy wire protruding from one tube of the fetotome is passed by means of the introducer via this incision and between thorax and the limb. The introducer is grasped under the limb, drawn outwards and pulled through the other tube of the fetotome. The head of the fetotome is placed between the shoulder joint and thorax. If necessary, this procedure is repeated for the other limb. Usually, extraction is easy after this procedure. 23 i Torsion of the spermatic cord, alternatively called testicular rotation (often, perhaps misleadingly, termed testicular torsion). In this case the torsion of the spermatic cord is about 180° with no problems in venous drainage and hence there are usually no other clinical signs, such as colic. No treatment is necessary. Some cases appear to be transient. ii The condition is characterised by the fact that the position of the caudal part (tail) of the epididymis has changed from caudal to cranial due to a disturbance in testicular descent. The posterior view shows a scrotum with two testicles and only one cauda epididymis (of the right testicle). No cauda epididymis of the left testicle is visible. This abnormality does not seem to affect fertility, but is a heritable abnormality and to breed with stallions having such an abnormality is not advisable. The condition is recognised in all breeds, but does occur more in certain breeds compared with others. Although the chronic permanent situation usually has no clinical signs, acute acquired testicular rotation usually results in severe colic signs.

26

24, 25: Questions 24 You are called to examine a broodmare which the stud farm manager has reported as being depressed and off her feed for a couple of days. Clinical examination reveals the findings shown 24a, b. i What are the two clinical signs shown? ii What possible diseases could cause these signs? iii On examination of a second in-contact mare, the feature illustrated in 24c was found. What is this feature and what disease would this make the most likely presumptive diagnosis? iv What laboratory tests would you use to confirm the diagnosis? v How would you attempt to control spread of the disease on the farm?

24a

24b

24c

25 What procedures are involved in the investigation of abortion?

27

24, 25: Answers 24 i Lower limb oedema and epiphora. ii A viral disease such as EVA, EHV-1, EHV-4 or influenza. iii Supraorbital oedema and inflammation of the conjunctiva (‘pinkeye’). This would make a presumptive diagnosis of EVA reasonable. However, clinical signs of EVA are highly variable and a definite diagnosis based on clinical signs alone is not possible. iv Virus isolation and/or serology. Virus can be isolated from nasopharyngeal swabs or the buffy coat of a heparinised blood sample. Virus can also be isolated from the semen of some affected stallions, fetal tissues and urine. Serological diagnosis is usually based on demonstrating seroconversion using virus neutralisation tests. Within 14–21 days following the acute stages of the disease strong antibody responses have usually developed. v Restriction of movement of horses on and off the premises, cessation of breeding, isolation of clinical cases and in-contact animals, institution of strict hygiene measures and screening of all animals on the premises by blood testing. The use of vaccination is also an important consideration in a control programme. 25 (1) Detailed clinical history, including the mare’s identity and breeding, past breeding history, movements, identity of the sire, breeding dates, vaccination details, health during pregnancy, events leading up to the abortion, nature of the birth, time of placental expulsion, any relevant environmental factors, and details of any other equine illnesses or losses on the premises or at the stud where the mare was bred. (2) Fetal examination. This should commence with weighing and measuring crown-rump length. Then check for state of preservation, growth retardation, malformations and deformities particularly those likely to obstruct the birth canal, state of the mucous membranes, signs of fetal diarrhoea and state of the umbilical area. The internal examination is easiest conducted with the fetus on its right side, and after the left abdominal and thoracic wall have been removed. Before handling organs, samples should be obtained for bacteriology (swabs from liver or heart, lung or stomach) and virology (liver, lung, thymus, and spleen into viral transport medium). The internal inspection should check for any of the ‘classic’ signs of EHV-l infection (excess serosal fluids, perirenal oedema, white spots on the liver, enlarged spleen with prominent splenic follicles, softening in the thymus, pneumonia) and other abnormalities including anomalies of development, abnormal stomach contents, state of the bladder and umbilical vessels, amount of air/froth in the airways and size of the thymus. Samples of liver, lung, thymus, adrenal, spleen and kidney should routinely be processed for histology. Keep a written record. (3) Placental examination. This should commence with noting which side was outermost and whether the tip of the non-pregnant horn is present (not retained in the mare). It should be spread out and each side scrutinised, particlar attention being paid to the shape. gross morphology and villus integrity of the chorion, the appearance of the amnion, and the length and the state of the vasculature and urachus in the umbilical cord. As the cervical ‘star’ is the usual site for ingress of bacterial infection into the uterus, it is the preferred site for routine bacteriological swabbing. To check for ascending placentitis, the star should be inspected closely, and routinely sampled for histology, along with at least two other more distal sites. (4) Final diagnosis. This is determined after consideration of all the facts, including the results of gross, histological and microbiological investigations. Serological examination of the mare may also be required.

28

26, 27: Questions 26 A bacterial isolate cultured from a mare’s cervix (26). The mare has a profuse vulval discharge a few days after covering. The organism has been grown in pure culture on chocolated agar under microaerophilic conditions. i What is the organism? ii What conditions are required to successfully culture the organism? iii What treatment would you give to the mare? iv What other action would you take?

26

27a

27b

27 A Thoroughbred mare was mated on three occasions 2 days apart. She was teased before each mating and showed signs consistent with being in oestrus. Unfortunately, it was omitted to tease her again after the day of the last mating. After the last mating, she was presented for pregnancy diagnosis 15 days later. Ultrasound examination of the left ovary is shown (27a); the right ovary had only small (35 mm) and a relaxed cervix; (5) there should be involution of the uterus and no excessive uterine fluid present; (6) as AI is to be used and can be accomplished by using a speculum, the state of healing of the original tear will only be relevant if an infection has ensued following repair. If this was significant to the extent of being a contaminating source of infection during insemination, then AI would be postponed until the mare had recovered from the infection/discharge. ii The mare could be bred in foal heat by means of AI provided she meets requirements as set out in (i). However if infection is present, or healing is delayed, the mare could be reassessed on the 18–19th day post partum and short cycled by using prostaglandin F2_, or alternately re-examined for healing, infection and follicle production on or about the 27th day post partum.

58

61, 62: Questions 61b 61a

61 An 11-year-old maiden mare used for showing has become unmanageable in the last few months and the owner is convinced that the behavioural changes are related to the oestrous cycle of the mare. You are called to examine the mare in early spring and, as part of your diagnostic work-up, you perform a rectal and ultrasonographic examination of the uterus, left (61a) and right (61b) ovary. i What are the ovarian findings and suggest a possible stage of cycle for the mare? ii How would you investigate the case further? iii What treatment would you suggest for the mare? iv What are the possible drawbacks to your treatment options?

62 A 3-year-old Warmblood mare has foaled her first foal and due to a head and leg displacement, has been presented to you 30 minutes after parturition with a severe 3rd degree perineal laceration (62). i What information would your preliminary assessment provide? ii When can you repair this type of injury? iii What two common surgical techniques can be used in this repair and how do they differ?

62

59

61, 62: Answers 61 i The left ovary contains several follicles of around 20 mm in diameter and no obvious CL is visible. In the right ovary there are two large follicles almost 40 mm in diameter. It is possible that the mare is in the follicular phase of the cycle. Bearing in mind the time of year, the mare could also be in the transitional phase when it is not uncommon to get single follicles growing to ovulatory size (up to 50 mm) before regressing. Very occasionally, several follicles of 40 mm or over develop either in both or even all in one ovary giving the temporary impression of a ‘cystic’ ovary (an inappropriate term in the mare) and an apparently inactive ovary. ii Blood samples for hormone analysis may be helpful. In addition, the mare should be examined on subsequent occasions to determine if her behavioural problems are related to oestrus. iii Where it is felt that the behavioural problems are truly linked to oestrus, daily supplementation with progesterone or a synthetic progestagen should prevent the mare showing oestrous behaviour. Another possibility would be to get her pregnant. iv Although rare in an unmated mare, there is a possibility of an increased risk for endometritis in a mare on long-term progesterone supplementation and she should be monitored for this. In addition, the problems may well recur following cessation of treatment. A drawback to getting the mare pregnant is that she will not be able to be shown in the later stages of pregnancy and after pregnancy the problems may reappear and, in addition, there may be some permanent shape changes due to the pregnancy which could detract from the mare’s showing potential. Removal of the ovaries is not successful in many cases and eliminates the use of the mare for breeding and should therefore be considered only after thorough client education. The case illustrates the importance of not presuming a large ovary in a mare with behavioural problems is due to a GTCT (see 41). 62 i (1) Assessment of heart rate and mucous membrane colour (increasing rate and blanching of the mucous membranes indicate possible internal haemorrhage); (2) careful palpation of the anterior vagina and rectum (a possible tear into the abdominal cavity or peri-rectal space); (3) assess the depth, site location of the tear and extent of severe deep-tissue injury; (4) eliminate injury to other pelvic organs if possible (uterine haemorrhage, middle uterine artery tear, prolapsed bladder, injury to the small or large colon by the foal’s hind legs). ii Where foaling and injury has occurred less than 3 hours before examination, immediate repair can be investigated but is rarely indicated. Usually severe bruising and laceration are present and repair should be delayed until granulation of the area occurs in 6–8 weeks or even longer. iii (1) The Aanes technique is a two-stage repair: stage 1 reconstructs the rectovestibular shelf but leaves the perineal body open; in stage 2, the perineal body is closed 3–4 weeks later. (2) The Goetze technique is a single-stage operation: the principle is to evert the rectal mucosa into the rectum and vaginal mucosa into the vagina with a form of purse string suture.

60

63, 64: Questions 63 With regard to the mare in 62: i What complications are most likely to cause disruption to your repair? ii What are the mare’s fertility expectations following surgery? iii What are the possible complications for future breeding and foaling?

64 The cervix of three different mares (64a–c). i In which stage of the oestrous cycle is each of the mares? ii Which other methods can you use to assess the shape and size of the cervix? iii How might an assessment of the cervix be useful in clinical practice?

64a

64b

64c

61

63, 64: Answers 63 i (1) If the vaginal shelf is too thin, this leads to development of a rectovaginal fistula and breakdown of the suture line; (2) constipation and severe post-surgical tenesmus; reduce the feed 24–48 hours pre-surgery (some clinicians favour even longer periods of starvation); use laxative feeds after surgery; (3) the sutures may break; using strong material, place single interrupted suture patterns in the rectum or vagina; (4) where the original injury caused severe tissue loss or where the injury occurred through the lateral rather than ventral rectal wall, there will be less tissue available for the vaginal shelf. This may cause eventual vaginal canal restrictions; (5) injudicious use of oral oil to soften faeces can cause leakage of oil through the sutured area and eventual dehiscence. ii Fertility should be good in young mares where an effective repair has occurred with good return of conformation of the rectum and vulva; there may be some reduction in older mares. iii (1) Repair has over-closed the vaginal canal; the mare may not be capable of natural mating and may require AI. Examination at the end of pregnancy may indicate the need for a caesarean section to prevent a repeat tear; (2) future foaling may cause a similar tear to happen but experience over 95 surgeries indicates this is less than a 3% possibility; (3) uterine infection from the original injury must be resolved and is usually not a problem in young mares as most conceive within 3–4 months of surgery. Old mares may require 10–12 months to regain normal fertility. 64 i During anoestrus (64a) the cervix is flaccid, dry and may be partially open. During dioestrus (64b), elevated concentrations of plasma progesterone cause the cervical os to close. The cervix is pale, tonic and dry and projects into the cranial vagina. The cervix during oestrus (64c) is usually moist and sometimes hyperaemic. The cervical os is usually open and oedematous. These changes are caused by elevated concentrations of oestrogen and basal progesterone concentrations. The cervix may rest upon the ventral floor of the cranial vagina. ii As well as direct visualisation using a speculum, information concerning the cervix can be obtained by palpation either per rectum or per vagina. When palpated per vaginum, the anoestrous cervix is dry, short and easily admits two fingers (although it may be tighter in maiden and older mares); per rectum it feels soft, wide and may be difficult to palpate. When palpated per vaginum, the dioestrous cervix is dry and finger like, and it may be difficult to locate the cervical os; per rectum, the cervix is firm, tubular and narrow. During oestrus the cervix readily admits two fingers when palpated per vaginum; per rectum, the oestrous cervix is broad and soft. iii Assessment of the endocrine status which may be useful for routine examinations, e.g. for early pregnancy diagnosis the cervix must be under the influence of progesterone (pale, dry, tonic and closed), and for determination of oestrus the cervix must be under the influence of oestrogen (oedematous, moist, broad and patent). Unless the cervix is palpated a misleading diagnosis may be reached; e.g. mares in prolonged dioestrus commonly have several large follicles, and palpation of the ovaries alone may lead to an incorrect assessment of the stage of the cycle – inspection or palpation of the cervix will reveal that the mare is under the influence of progesterone.

62

65, 66: Questions 65a

65b

65 A 12-year-old mare was examined every second day during oestrus and mated when there was a 40 mm and a 30 mm follicle in the left ovary. Two days later the left ovary appeared (65a). The mare was not mated again. When examined somewhat early for pregnancy 14 days after mating, the left ovary appeared (65b) and examination of the uterus indicated the presence of what appeared to be a 4 mm embryonic vesicle in the left horn. i Is it reasonable to pronounce the mare pregnant and what further action would you take? ii How you would proceed with the case? iii What are the various possibilities that may be detected on subsequent ultrasound examination of the uterus?

66 A Thoroughbred foal 2 months old with no previous illness suffered a sudden onset of pyrexia and dyspnoea. It did not respond to therapy and died after 36 hours. An autopsy revealed diffuse interstitial pneumonia: no bacteria or virus were isolated. The histological appearance of a Crocott silver stain on lung is shown (66). i What is your diagnosis? ii Under what circumstances is this condition more often seen?

66

63

65, 66: Answers 65c

65 i Two days after mating there was an obvious large follicle in the left ovary, but also an adjacent indistinct ovulatory area. Careful examination of the same ovary at the time of the examination for pregnancy reveals the presence of two mature CLs. It would therefore seem probable that the 40 mm follicle ovulated on the day of the examination 2 days after mating and the smaller follicle shortly afterwards. There is a chance of a twin pregnancy, but on the day of the pregnancy examination, the younger embryonic vesicle formed as a result of fertilisation of the oocyte from the later ovulation would be too small to be detected on the ultrasound examination. It would be premature to pronounce the mare pregnant on the basis of what appeared to be a 4 mm embryonic vesicle, but which could also be a small endometrial cyst which had not been recorded at previous examinations. The owner should be warned of the possibility of a twin pregnancy and its serious consequences. ii The mare should be re-examined: ideally in 3 days; alternatively after 2 and then, if necessary, again after 4 days. iii (1) After 3 days a second embryonic vesicle, if present, should be visible on ultrasound examination. Unless the second ovulation occurred more than 2 days after the first, the vesicle should be of a convenient size to crush. (2) If the mare is re-examined after 2 days, depending on when the second ovulation occurred, the smaller embryonic vesicle may or may not be visible. If only one embryonic vesicle is present then the single pregnancy should not be confirmed until after a further examination. (3) If the mare is re-examined after 4 days, twin vesicles could be found in a unilateral location and, therefore, more difficult to reduce successfully to a singleton pregnancy by crushing one of the vesicles. If one vesicle is considerably smaller than the other, but positioned so close to the large vesicle (65c) that the procedure of vesicle reduction by crushing is likely to result in disruption of the larger vesicle also, it may be preferable to monitor the progress by subsequent ultrasound examinations. 66 i The clinical syndrome, the presence of interstitial pneumonia and the argyrophilic bodies within lung alveoli are all indicative of a Pneumocystis carinii infection. An avidin-biotin immunostain of lung sections help to confirm this. ii This organism is an opportunist pathogen and in the USA has been most commonly recognised in immunocompromised Arab foals with combined immunodeficiency. In the UK several cases have occurred in Thoroughbred foals not known to be suffering from an immune deficiency.

64

67, 68: Questions 67 i Name these instruments used for percutaneous fetotomy in the mare (67). ii What are the principal indications for complete and partial fetotomy? iii How would you prepare the mare for fetotomy? iv What are the principal complications?

67

68

68 A 12-year-old broodmare, purchased last year already in foal, was induced with oxytocin IV at 350 days gestation because of poor condition due to multicentric lymphoma (68). Minimal mammary development was present at the time of induction. The mare gave birth to a small foal that has many of the characteristics of dysmaturity. The placenta was passed intact and appeared grossly normal Although in the first hour or two after induction the foal appeared to be vigorous and alert, it has still flailed to stand. It does have suckle reflex and the owner has supplied colostrum that the foal ingested by bottle. A CBC reveals a total WBC count of only 0.9 × 109 cells/L (900 cells/+L) and a fibrinogen of 1 g/L (100 mg/dL). (Intensive care facilities are available and money is not a problem.) i What is your long-term prognosis? ii What is your therapy for this foal?

65

67, 68: Answers 67 i Utrecht fetatome with hardened steel head, wire introducer, saw wire, fetatome threader, wire saw handles, fetotomy knive, long hook and Krey hook with attached obstetrical chain. ii For complete fetotomy: (1) a dead fetus which is absolutely or relatively oversized. This indication is relatively rare in the mare because of the favourable fetopelvic proportion. It may happen in the Belgian draught horse or the Shetland pony. In the latter breed, this is an indication for a caesarean section and not for fetotomy. A fetotomy performed in this breed often results in serious vaginal and cervical adhesions; (2) pathologically enlarged fetus or fetal ankylosis. For partial fetotomy (dead fetus): (1) ventral or lateral deviations of the head; (2) hydrocephalus; (3) transverse presentation, if the fetus is accessible; (4) other abnormal fetal postures and fetal deformities or ankylosis. Although a complete fetotomy in particular is more difficult in mares than in cows, a correct and quick fetotomy performed by a skilled veterinarian is a comparatively safe obstetrical treatment. In many of the afore mentioned cases, fetotomy may avoid the need for caesarean section usually resulting in a shorter recovery time and less aftercare. Moreover, most cases only demand partial fetotomy comprising 1–3 sections. When a complete fetotomy may be necessary, the skill of the obstetrician, the case history, the breed and the other circumstances will be decisive for the choice of fetotomy versus caesarean section. iii The standing position is preferred. If available, the mare is placed in stocks with abdominal support. Tranquilisation may be necessary. The fetotomy is performed under epidural anaesthesia. In the recumbent animal, the treatment is performed under epidural or general anaesthesia. Thorough cleansing of the entire area is important. For protection of both the animal and the obstetrician, lubricant must be used in copious amounts. iv Especially when performed by a less skilled person or under unfavourable circumstances, fetotomy may result in severe damage to the uterus (including rupture), cervix or vagina. Damage to the cervix may lead to cervical incompetence. 68 i The foal has a poor prognosis for survival even with intensive care. There is no evidence that this foal was ‘ready for birth’ and consequently probably lacks many of the hormonal changes responsible for maturation of many systems, including the lungs and immune system. The low total WBC count reflects inadequate maturation, most likely related to inadequate fetal nutrition due to severe maternal disease. The initial vigour observed is commonly seen in these foals and may be due to temporary sympathetic surges The prognosis is not hopeless as some foals fitting this scenario have survived, but usually require intensive care and support. Surviving foals are prone to many complications, including carpal and tarsal bone collapse, angular limb deformities and pneumonia ii Therapy for these foals is controversial. Cortisol is important for certain maturation processes; many believe that administration of ACTH or exogenous cortisone is warranted. Daily evaluation of total leucocyte count is also helpful in determining day-to-day prognosis. It is likely that this foal will require intensive support including fluid therapy, parenteral nutrition and, possibly, blood pressure support with IV fluids, plasma, dopamine or dobutamine.

66

69, 70: Questions 69a

69b

69 These two ovaries (69a, b) are similar in size and upon palpation. i Which structures does each ovary contain? ii In which stage of the oestrous cycle is each of the mares? iii How might you differentiate these ovaries in the clinical situation?

70 A term 28-hour-old 70 Thoroughbred colt is sleepy and recumbent (70). Birth was assisted and examination of the placenta revealed evidence of premature separation. The colt has never stood without assistance, was poorly responsive to stimulation and had no suckle reflex. Pulse rate and rectal temperature were normal. The pattern of breathing was periodic fluctuations in frequency with lengthy periods of apnoea, the overall rate was estimated at 10–12 breaths/minute. An arterial blood gas sample was pH = 7.185, PaO2 = 62 mmHg, PaCO2 = 85 mmHg, HCO3 = 31 mmol/L (31 mEq/L). i What are your differential diagnoses? ii What is your interpretation of the blood sample? iii What options are available for medical management? iv What is your prognosis?

67

69, 70: Answers 69 i Figure 69a contains several small follicular structures. None are palpable since they are less than 2 cm in diameter and therefore do not protrude above the margin of the ovary. Figure 69b contains three follicular structures and a CL. None of these structures can be palpated since they do not protrude above the margin of the ovary. ii The first mare (69a) is likely to be in anoestrus (assuming the opposite ovary has a similar appearance). The second mare (69b) is in dioestrus; the CL is producing progesterone. iii The first mare (69a) will not be exhibiting oestrous behaviour, although this is possible if she were in the period of vernal transition. The second mare (69b) would have recently had oestrous behaviour. The cervix of mare 69a would appear flaccid and relatively dry, and may partially gape open. When palpated, the cervix of this mare would allow two fingers to be placed through the cervical os. The cervix of mare 69b would be pale, tonic and dry and would project into the cranial vagina. When palpated, the cervix would be firm and narrow and would not allow the admission of a finger into the cervical os. Plasma progesterone concentrations would be basal in mare 69a and elevated in mare 69b. Progesterone concentrations can be easily measured by use of an ELISA technique. 70 i (1) HIE (also referred to as NMS). The pattern of breathing is consistent with classical Cheyne–Stokes respiration. (2) It is important to rule out a septic process by submission of a CBC and fibrinogen estimation, calculation of a sepsis score and collection of blood for bacterial culture. (3) Congenital brain defects occur rarely, but can be difficult to distinguish from HIE. The young age (7.3), as can occur with chronic respiratory acidosis, it could be argued that no assistance to ventilation is needed. When moderate to severe acidaemia is present, chemical stimulation using doxapram infusion has been effective in reversing neurological-induced periodic breathing. Assisted ventilation using a simple resuscitation bag may be adequate at temporarily reversing the respiratory acidosis. In severely affected foals a mechanical ventilator is needed. iv Guarded to poor, despite appropriate supportive therapy. Foals with HIE have a much improved prognosis if they demonstrate more normal behaviour during the first 1–12 hours of life before developing neurological disease.

68

71, 72: Questions 71 i What special factors would you consider when anaesthetising a young foal? ii How you would anaesthetise a young foal?

72 On routine teasing, a mare was showing signs of oestrous behaviour and then presented to you for gynaecological examination. On rectal and ultrasound examination of the left ovary you find a 4 cm soft, slightly tender structure (72a). In the right ovary there are small follicles and no CL. The cervix and uterus have very little tone and the left uterine horn is illustrated (72b). What is your advice?

72a

72b

69

71, 72: Answers 71 i To avoid the mare becoming too distressed at the absence of her foal, the mare should be sedated. Foals are not just small adults: they have immature metabolic and homeostatic processes which will not be fully functional. Care needs to be taken so that these immature body systems are not overchallenged with the anaesthetic protocol. The small size, low body fat and thermoregulatory mechanisms which are depressed by general anaesthesia mean that the foal is prone to lose body heat more rapidly than an adult. Prevention of heat loss is easier than warming a cold animal – prevent hypothermia with bubble wrap/space blankets and especially critical to ensure that IV or irrigating fluids are prewarmed. Foals have low fat stores so use IV fluids with additional glucose to avoid an hypoglycaemic episode in recovery. The period of preoperative starvation can be minimised for the same reasons (regurgitation is uncommon in foals). Foals can be left with the mare until just prior to induction since they suckle small amounts frequently rather than having infrequent gorges which might present more risk of regurgitation. Foals have low plasma albumin and require lower doses of albumin bound drugs, e.g. barbiturates, than older animals, but are relatively resistant to non-albumin drugs, e.g. ketamine. Foals also have immature hepatic/renal clearance mechanisms and so it is probably better to slightly under dose a foal. Foals are prone to the respiratory depressant effects of the anaesthetic and should always be intubated and given oxygen-enriched gases. Artificial ventilation is sometimes needed for even short procedures. New-born animals are more dependent on heart rate to maintain cardiac output. Drugs which cause bradycardia should be used with caution. Foals are prone to gastric ulceration associated with the stresses of surgery and administration of oral sucralfate before and after surgery, has a high protective benefit for a relatively low financial cost. ii The alpha-2 agents (xylazine, detomidine, romifidine) are widely used at their adult dose rates, but have profound effects on the cardiovascular system. Combining their use with an opiate, e.g. butorphanol (i.e. neuroleptanalgesia) will require about half the dose of each drug if each were used on their own and yet have considerable synergism. The concomitant use of benzodiazepines with the induction agent have increasing support. This combination allows the dose of the alpha-2 sedative to be halved with ensuing cost and risk benefits to the patient. Induction using inhalation halothane appears to work well, but recent evidence has suggested this carries greater risk than an IV induction with e.g. ketamine, which may be preferable – especially if used in combination with diazepam or midazolam. Barbiturates are less suitable since they have profound depressant activity on the cardiovascular and respiratory systems and can lead to prolonged recovery. If the foal is allowed to be with the mare during induction the stress of separation is avoided. Maintenance of anaesthesia can be carried out with either halothane or isoflurane. 72 The mare appears to have follicles, very close to ovulation in both ovaries. Note their size, non-spherical outline and the thickened hyperechoic walls. There is only slight uterine oedema. Therefore, the mare should be mated within the next few hours and re-examined to confirm twin ovulation in 2 days.

70

73, 74: Questions 73 An 8-week-old Thorough73 bred colt presents with a complaint of rapid onset (over the past 48 hours) of weakness progressing to flaccid paralysis (73). It has increased abdominal effort on respiration, with decreased thoracic excursion and decreased tongue and tail tone, and is unable to maintain sternal recumbency. Heart rate and respiratory rate are moderately elevated at 100 and 24/minute, respectively, and rectal temperature is normal. The foal is alert and aware of its surroundings. i What is the most likely location of the neurologic lesion? ii What are the two most likely differential diagnoses, and how might you differentiate them? iii What preventive measures can you take to prevent each of these diseases? 74 Five ejaculates of semen from different stallions are evaluated: Ejaculate 1 Ejaculate 2 Ejaculate 3 Ejaculate 4 Ejaculate 5 Gel-free volume (ml) Sperm concentration (×106/ml)

40

80

80

30

190

250

100

20

175

10

Other semen parameters (morphology, motility, etc) were normal except for ejaculate 5, which had very low spermatozoa motility. i Which ejaculate do you prefer to use for insemination of a number of mares and why? ii Comment on the colour of each ejaculate (74). iii Assuming a progressive motility of 70% and 65% morphologically normal spermatozoa for ejaculate 1, how many mares could be inseminated with this ejaculate?

74

71

73, 74: Answers 73 i Generalized peripheral neuromuscular or muscular problem. Although a metabolic disorder, such as hypoglycemia, is possible, the foal should have historical or physical examination findings indicating the presence of an underlying primary disease. A focal spinal cord lesion could account for the paralysis, but would not explain the decreased tongue and tail tone. ii Botulism and white muscle disease (nutritional myodystrophy). Foals with white muscle disease often exhibit a period of muscular pain and stiffness before progressing to flaccid paralysis. Geographic location is helpful in differentiating the diseases, as white muscle disease occurs in areas where the soil is selenium deficient. Serum creatine phosphokinase activity should be higher in a foal with white muscle disease than one with botulism, although the latter may be moderately elevated due to compromised perfusion of dependent muscle masses. iii In endemic regions, vaccination against Clostridium botulinum is recommended. In selenium deficient regions, mares should receive a selenium supplemented ration and foals should be treated prophylactically with injectable vitamin E and selenium at birth. 74 i Ejaculate 1 as this has the highest amount of sperm cells (10 × 109). Ejaculates 2, 3, 4 and 5 contain respectively 8.0 × 109, 1.6 × 109, 5.25 × 109 and 1.9 × 109 sperm cells. Ejaculates 4 and 5 are abnormal, because they contain either blood or urine, and are not suitable for insemination. ii The colour of a normal ejaculate ranges from watery grey to creamy white depending on the sperm concentration. For ejaculate 1, the colour is white indicating a highly concentrated ejaculate. An ejaculate with a lower sperm concentration looks more greyish/white (ejaculate 2) or grey (ejaculate 3). An abnormal colour as found in ejaculates 4 and 5 can indicate contamination with blood or urine respectively. A rose-pink/reddish colour indicates that blood is mixed with the semen. This can be due to infection of the internal genital tract, such as bacterial urethritis or traumatic damage to the penis. Stallions with haemospermia are subfertile, probably due to the presence of erythrocytes which can affect the seminal parameters. Treatment consists of sexual rest and treating any infection present. Contamination with urine is readily detectable by a characteristic yellow colour and ammoniacal odour. The cause is unknown and the yellow colour can also be a sign of infection. It is important to diagnose the condition due to the severe reduction in motility of the sperm cells. Management offers the best approach: if AI is permitted, collect semen immediately after urination. iii Mares should be inseminated with a minimum of 300 million morphologically normal progressively motile sperm (TNM). Ejaculate 1 is sufficient for the insemination of 15 mares ((40 × 250 million × 0.70 × 0.65) = 4,550 million ÷ 300 million = 15).

72

75, 76: Questions 75a

75b

75c

75d

75 Routine examination of placentas after foaling is strongly recommended. i What is this structure attached to the chorion (75a)? ii What are the red dots on the chorion surface (75b)? iii What are these objects seen in two placentas (75c)? iv What is the the appearance of this chorionic horn (75d)?

76 A 12-year-old 10 months’ pregnant mare has had a slight bloody vulval discharge for two days. No abnormalities were revealed on general and rectal examination. However, vaginal examination showed the condition illustrated (76). i What is this condition? ii How would you treat this abnormality? iii What other problems can be responsible for haemorrhagic vulval discharge during pregnancy?

76

73

75, 76: Answers 75e

75 i In each placenta there is a vestigial yolk sac remnant within the allantoic part of the cord. This is a particularly large one, which although still attached to its usual location, has protruded into the allantoic cavity. Some have calcifying bony plaques in the wall, which is why they are sometimes mistakenly identified as twin remnants. ii Mature microcotyledons which cover the outer surface of the chorion (75e, SEM view). Each fits exactly into a microcaruncle in the endometrium. Fetal development and health depends on the integrity of these structures. iii These are hippomanes, soft putty-like aggregates of urinary calculus which form throughout pregnancy and are present in all placentas in the allantoic cavity. Fragments can sometimes be found in the urachus. They vary in colour and size and have a layered appearance when cut. iv This is typical of the tip of the pregnant horn at term. The arrow points to the avillous site over the ostium of the oviduct. There are two oedematous plaques, one at the horn tip and one ventrally opposite the ostium. The latter often shows a pale area of villous atrophy and a green mucoid deposit. These changes are probably caused by local pressure from the fetal hind feet. 76 i Vaginal venous varicosities. During normal pregnancy, vulval discharge should not be present. However, some mares may show slight intermittent haemorrhagic or mucous discharge during the last trimester of pregnancy. In many cases, this discharge originates from vaginal varicose veins. Vaginal examination reveals a plexus of dilated (up to 5 mm diameter) veins cranial to the urethra (76), usually located at the vaginovestibular junction. Rupture of one or more of these veins may result in blood loss via the vulva. ii In general, the course of pregnancy is not disturbed by these vaginal varicose veins. Treatment is only required in case of persistent or increasing and substantial blood loss. Bleeding veins can be ligated or thermocauterised. Usually, varicosities disappear or shrink spontaneously after parturition. iii Blood loss and/or purulent discharge during pregnancy may also be the result of placentitis, placental bleeding or separation. Differential diagnoses also include interrupted twin pregnancy, cystitis, urethritis and urolithiasis. A careful extensive examination should reveal the source of the discharge.

74

77, 78: Questions 77a

77b

77c

77d

77 A mare at stud was showing signs of oestrous behaviour on routine teasing and was then presented to you for gynaecological examination. On rectal and ultrasound examination of the left ovary you find a soft 35 mm soft, slightly tender structure, confirmed as a follicle on ultrasound examination. In the right ovary there is also a 35 mm softish structure (77a). The cervix and uterus have slight tone. The mare was mated the same day as this examination and when re-examined 2 days later, the left and right ovary were as illustrated in 77b, c and the right uterine horn as in 77d. What are the ultrasound findings and your advice to the stud farm?

78 When a popular stallion is used in an AI programme, his semen is transported all over the country, often being used to inseminate as many as 300 mares in a season. Consequently, it is important to know how much semen he produces. How can you determine the sperm production of a stallion?

75

77, 78: Answers 77e

77 i When the mare is re-examined after mating, in the left ovary there is a normal echoic CL approximately 48 hours old. Palpation of this ovary reveals a softish, rubbery area which could easily be overlooked if its presence was not suspected. In the right ovary, however, there is a CL at least 3 days old and probably nearer 5 days in age. The age can be estimated from the degree of organisation of the echoic matrix (probably fibrin) in the central anechoic lacuna. In the right uterine horn there is an accumulation of hypoechoic fluid, almost certainly an inflammatory exudate. This could be confirmed by appropriate cytological and bacteriological investigations. Palpation of the right ovary reveals an obvious, spherical structure, not easily distinguished from a follicle; the fluid enlargement of the uterine horn is not detectable on rectal palpation. If the structure in the right ovary is a CL more than 48 hours old, then the mare had already ovulated at least 36 hours before the time of mating and so a pregnancy will not result from this mating. A pregnancy from the ovulation in the left ovary is quite possible, but because the mare was mated after the first ovulation, when the peripheral plasma progesterone concentrations would be rising and the cervical canal becoming constricted, the mare has been unable to eliminate the otherwise transient post-mating endometritis due to bacterial infection. The mare is now at least 3.5 days after the first ovulation. If all the inflammatory exudate can be rapidly eliminated from the uterus she still has an albeit small chance to become pregnant, but if the inflammation persists more than another 12–24 hours, then a massive inflammatory response will ensue with bacterial multiplication, release of prostaglandin F2_ and an early return to oestrus. In retrospect the advice given to mate the mare was incorrect because a follicle close to the point of ovulation was seen in the left ovary, it was assumed that the structure in the right ovary was the same. It was in fact a corpus haemorrhagicum (early CL) with an exceptionally large central haemorrhagic lacuna and an unusually narrow luteal border. Transiently such CLs can be mistaken for follicles; 24 hours earlier it might have appeared as an echoic area with a small pocket of fluid (77e). 78 The key is knowing his DSO. The DSO is defined as the total number of morphologically normal progressive motile spermatozoa (TNM) produced in an ejaculate on a daily basis. DSO can be determined by collecting semen once per day over a period of 10 days and expressed as TNM per day. When a stallion has not mated for a considerable period, the total number of spermatozoa in the ejaculate will be high and so will the TNM. If he is collected every day, the total number of spermatozoa ejaculated per day will usually reach a constant level during the second week of collection. At that point, you will know how many spermatozoa the stallion produces per day and, therefore, what you can rely on when calculating amount of insemination doses likely to be possible for that particular stallion. Several factors can influence the result of semen collection, therefore, you should aim to keep the circumstances of collection constant and optimal.

76

79, 80: Questions 79a

79b

79 A 4-week-old foal is presented for assessment (79a, b). i What is your diagnosis? ii What treatment is likely to be necessary? iii What is the prognosis for racing? 80

80 A 3-day-old foal has a 12-hour history of colic, abdominal distension and diarrhoea (80). The foal is recumbent, poorly responsive to stimulation and dehydrated. The diarrhoea is profuse and watery and has a foul odour. Pulse and respiratory rates are elevated, but auscultation of the thorax is normal. A CBC reveals neutropaenia with a degenerative left shift and marked toxicity present in circulating granulocytes. An ELISA test for IgG returns an estimation of 2 g/L (200 mg/dL). i What are your differential diagnoses? ii What additional diagnostic tests could you perform?

77

79, 80: Answers 79c

79d

79 i Severe carpal valgus affecting the right forelimb with an associated carpal flexural deformity. ii With carpal valgus as severe as this, the foal must be confined to a stable to prevent crushing injuries of the carpal bones. Conservative measures should always be tried first as many cases of carpal valgus will self-correct. However, in this case there was still severe carpal valgus present when the foal reached 6 weeks of age. Radiographs showed that there was a degree of compression of the distal radial growth plate (79c) and surgery was carried out. This involved the placement of two titanium screws linked by wire across the distal radial growth plate of the right knee (79d). This established immediate transepiphyseal compression. The foal was confined to a stable and the implants were removed once the limb had straightened. The flexural deformity corrected itself and a good cosmetic result was obtained. iii Good, although this is worsened if a degree of rotation occurs along with the carpal valgus or if the cuboidal bones have been compressed or fractured. 80 i Septicaemia, salmonellosis, clostridial infection, Escherichia coli or viral diarrhoea (rotavirus, coronavirus, parvovirus). The severity of the clinical signs would make nutritional and parasitic causes unlikely. Cryptosporidium has been reported as a cause of diarrhoea in older foals, especially immunocompromised animals. Abdominal distension due to uroperitoneum can be distinguished from intestinal gas by physical examination and ultrasound. Failure of passive transfer is suggested from the low lgG quantification. ii Blood and faecal culture, abdominal ultrasound examination and abdominal radiography. Additional tests may include a faecal test for rotavirus. To identify crytopsporidium oocysts a faecal flotation in saturated sugar solution and/or immunofluorescent staining is required. In addition to the CBC and fibrinogen, an arterial blood gas and serum biochemical profile are also indicated. In this foal, both blood and faecal culture were positive for Group B Salmonella. The ultrasound examination revealed distended small and large intestine. Umbilical structures were within normal limits. Gas-distended small intestine, caecum and large colon were noted on abdominal radiography.

78

81–83: Questions 81 With regard to the foal in 80, arterial blood gas analysis revealed acidaemia (pHa = 7.127, PaO2 = 79 mmHg, PaCO2 = 46 mmHg, HCO3 = 14.7 mmol/L (14.7 mEq/L). i What is your interpretation of the arterial gas analysis? ii What is your treatment plan?

82 After an uneventful birth a full-term foal gasps and then dies. i What can you see on opening the chest (82)? ii What congenital anomaly may also be present?

82

83 The normal ovaries from two different mares (83a, b). i Which of the ovarian surfaces are covered in visceral peritoneum? ii What is the function of the caudoventral depression of the ovary? iii What is the mass of tissue positioned at this depression?

83a

83b

79

81–83: Answers 81 i Mixed metabolic and respiratory acidosis probably due to a combination of electrolyte loss and poor tissue perfusion (secondary to reduced plasma volume and septicaemia). Examination of the anion gap ((Na + K) – (Cl + HCO3)) may give some insight into the relative contribution of either electrolyte loss through diarrhoea or dehydration and sepsis to the acidosis. When there is poor tissue perfusion anaerobic glycolysis and lactate production will take place, resulting in an increase in circulating anion (lactate) and therefore an elevated anion gap. In this foal, the expected respiratory response would be to increase ventilation as a compensation for the metabolic derangement. The inadequate ventilatory response was attributed to abdominal distension ii (1) Fluid therapy, initially IV, then oral. Glucose or dextrose are commonly added to fluids to prevent hypoglycaemia. (2) Bicarbonate therapy, but over-zealous bicarbonate replacement may convert a moderate metabolic acidosis into a moderate to severe respiratory acidosis with a net reduction in blood pH. Simple rehydration with an IV replacement electrolyte solution may itself cause significant improvement in the acid-base status. (3) Antimicrobials: broad-spectrum. (4) Anti-ulcer medication: histamine type 2 receptor antagonists, such as ranitidine or cimetidine. (5) Anti-diarrhoeal preparations: bismuth subsalicylate, kaolin, pectin or activated charcoal. (6) Plasma transfusion: not only for IgG but also for the addition of oncotic protein for vascular support. (7) Nutrition: with all neonatal diseases nutrition is of extreme importance. Unfortunately, it may be impossible to continue to feed milk or a milk replacer to a foal with colic. Consideration should be given to using total parenteral nutrition. (8) NSAIDs, such as flunixin meglumine. 82 i Much of the alimentary tract is located within the thorax. The reason for this was an extensive diaphragmatic defect/malformation. ii The displacement of the viscera into the thorax had been present for a considerable time. The congenital diaphragmatic hernia was accompanied by pulmonary hypoplasia. 83 i The dorsal, lateral, medial and much of the ventral surfaces of the ovary are covered by visceral peritoneum. This is of significance since it is not possible for rupture of the ovarian stroma to occur in these areas. Ovulation may only occur on the surface without visceral peritoneum, i.e. caudoventrally. ii It is the only portion that remains uncovered by visceral peritoneum. It is termed the ovulation fossa, and it is from this specialised area that ovulation always occurs; germinal epithelium is confined to this region. The follicle may reach this region because of its size or because it develops an outpouching along a line of least resistance towards the fossa. This is assisted by the presence of bands of connective tissue within the ovarian stroma which radiate outwards from the ovulation fossa. iii The infundibulum: the funnel-shaped cranial portion of the oviduct, which has an irregular margin comprising of fimbriated tissue. At the cranial edge of the infundibulum the fimbria are attached to the ovary to form the cranial pole of the ovulation fossa. During ovulation the infundibulum lies over the ovulation fossa to facilitate entry of the oocyte into the oviduct.

80

84, 85: Questions 84a

84b

84 A mare is presented for pregnancy diagnosis 30 days after ovulation. Based on an explanation of each of the ultrasound images (84a–c), what is your diagnosis and advice to the owner?

84c

85 A 9-month pregnant mare had been showing mild, occasionally moderate signs of colic for 5 hours. On rectal palpation the fetus could not be reached, but the left broad ligament was strongly stretched in a ventral direction. The right ligament showed less tension and was running diagonally from the right sublumbar fossa to the left ventrolateral area under the uterus, crossing the left ligament at its cranial site. Vaginal inspection revealed no abnormalities. i What is your diagnosis? ii What is your prognosis? iii How would you treat the mare?

81

84, 85: Answers 84 Figure 84a is a normal 30-day pregnancy. The allantoic cavity approximates the yolk sac in cross-sectional area so that the embryo is suspended in the centre. The heart-beat should be clearly visible at this stage of pregnancy. Figure 84b is an undersize (‘small for gestational age’) vesicle in which no embryo has developed nor is likely to develop. Prostaglandin F2_ should be administered. Figure 84c is a twin pregnancy of about 30 days. It is difficult to identify all 4 compartments (2 × yolk sacs and 2 × allantoic sacs), but the identification of two embryos with obvious heartbeats is sufficient to make a definite diagnosis of twin pregnancy. The options suggested are either (1) immediate administration of prostaglandin F2_ followed 2 days later by a repeat dose unless endometrial oedema is obvious indicating that the mare is returning to oestrus and luteal regression has occurred. In addition, flushing of the uterus with a litre of physiological saline is recommended to be certain of removing the embryonic vesicles. (2) Transvaginal ultrasound guided needle-puncture of one of the vesicles can be attempted. In is inadvisable to leave the pregnancies and hope for natural reduction as the likelihood of a single pregnancy resulting from a twin pregnancy with both embryos having obvious heartbeats at 30 days is small. 85 i Uterine torsion; the position of the broad ligaments clearly points to a counterclockwise rotation of the uterus. The fetus, normally palpable at this stage of gestation, is not usually palpable in a case of uterine torsion as a result of its cranial displacement in the abdomen. In a case of uterine torsion, the insertion of the broad ligaments at the lesser curvature usually cannot be palpated. Uterine torsion is a relatively rare complication during pregnancy and usually occurs between 9 months and term. ii The prognosis depends on the degree of torsion, duration of the clinical signs, complications during treatment and the stage of pregnancy. Prolonged, severe (>270°) torsion may lead to death of the fetus and uterine rupture. This patient has a good prognosis. The same is true for the foal if still viable at the time of treatment, which is very likely. Some 80% of such mares will deliver their foal at normal term. However, the foal will be usually aborted within 2 days when found to be dead at the time of surgery. iii Surgical correction by a standing (high) flank incision has proven to be a reliable way of treatment. The dorsoventral incision (15 cm) is made on the side of the abdomen toward which the uterus is rotated. This makes correction rather easy at this stage of pregnancy. The operation takes place after sedation and under local infiltration anaesthesia. After correction, the location and state of the ligaments, the state of the uterine wall and the vital state of the fetus should be evaluated. After surgery, treatment with a tocolytic drug and broadspectrum antibiotics for 2–3 days is indicated. Manual rotation of the uterus through the cervix may be successful when the mare is in the process of parturition. Some cases of uterine torsion can be corrected by a rolling procedure; however, rupture of the uterus or serious damage to the ligaments is a potential risk with this procedure.

82

86, 87: Questions 86 What are the special requirements for a foal undergoing surgery for repair of a ruptured bladder?

87 i What are 87a–c examples of? ii How are they prepared? iii What are the general principles involved in the assessment? iv What are the features present in each of the specimens and what is their significance?

87a

87b

87c

83

86, 87: Answers 86 This patient will need careful preoperative assessment and treatment. The foal is likely to be less than a week old, be hypovolaemic, have cardiorespiratory embarrassment due to a distended abdomen and have severe electrolyte abnormalities (hyperkalaemia, hyponatraemia, hypochloraemia and uraemia) and have a metabolic acidosis. This array of metabolic derangements may lead to life-threatening cardiac dysrhythmias. Cases which have progressed for several days often have complications relating to anaesthesia, such as third degree block, which may be resistant to atropine. Correction of the underlying electrolyte abnormalities is important. Circulating blood volume should be restored with a crystalloid solution low in potassium, e.g. isotonic saline, which will restore the sodium and chlorine deficit. Bicarbonate in 5% dextrose solution may be needed if a severe metabolic acidosis exists. Hyperkalaemia can also be treated with insulin and glucose (0.1 IU/kg insulin and 0.5 mg/kg dextrose in 500 ml saline). The urine should be drained from the abdomen to relieve the abdominal distension (and reduce respiratory embarrassment) and remove the toxic metabolites. To avoid precipitating dysrhythmias (increased in likelihood because of the electrolyte abnormalities) it is best to avoid the alpha-2 adrenergics in the sedative premedication. Diazepam and ketamine induction (without prior sedation) followed by gaseous maintenance with halothane or isoflurane is a good combination. Tilting the animal towards the hindquarters during surgery will minimise pressure on the diaphragm from any fluid in the abdomen. An emergency box with a sheet of pre-calculated doses of emergency drugs (glycopyrrolate, adrenaline and lignocaine) should be available to treat any cardiac dysrhythmias. 87 i Slides of sperm cells stained to evaluate their morphologic features. ii Thoroughly mixing a drop of the raw semen with a drop of aniline-blue eosin or eosin nigrosin stain on a clean microscope slide. A smear is air-dried to allow the morphology to be evaluated under a light microscope at ×1,000 magnification with oil. A stain containing eosin can pass through damaged membranes, but not through intact plasma membranes, so this method can also be used to differentiate between live and dead spermatozoa. iii To assess sperm morphology, reference to a standard is useful to ensure consistency. As a wide range of abnormalities can be present, it is recommended on statistical grounds that 200 sperm cells of which at least 100 are alive should be evaluated. For each individual sperm cell only one abnormality (the most proximal) is scored. Finally, the percentage of normal, live spermatozoa is calculated. This percentage can vary between 5% and 85%; above 50% is generally considered acceptable for breeding. iv In 87a, a normal spermatozoa consisting of a head, mid-piece, tail and end-piece. In 87b, an abnormal acrosome (irregular apical ridge and white dot). In 87c, an abnormal tail, bent tail and dead sperm (red). The exact significance of abnormalities is not clear. In general, no single abnormality is significant unless it occurs in more than 5% of the total spermatozoa. A more important parameter is the percentage of morphologically normal, unstained spermatozoa.

84

88, 89: Questions 88

88 In July a group of broodmares is turned out on to a pasture that was used by a circus earlier in the year. Four weeks later 3 mares develop a chronic cough and dyspnoea. Obvious respiratory wheezes and crackles are audible on thoracic auscultation. Otherwise the animals are bright and continue to graze. Tracheal endoscopy demonstrates a small amount of mucopus accumulation. Figure 88 shows a cytospin preparation of bronchoalveolar lavage fluid from one mare. i What is the main cytological abnormality and what is your diagnosis? ii What is the most likely aetiological agent? iii What therapy and management would you recommend?

89 A 2-month-old Shire cross colt foal was presented with a hind limb lameness of 10 days standing and a swollen right tarsocrural joint (89a). The foal appeared slightly depressed but was well developed for his age. He was lame at the walk (3/5 on the right hind leg) and resented palpation and flexion of the right hock. The foal’s rectal temperature was 38.6°C. i What is your diagnosis? ii How would you confirm it? iii What treatment is required?

89a

85

88, 89: Answers 88 i There is a marked eosinophilia of the bronchoalveolar lavage fluid. Normally eosinophils comprise no more than 1% of the cell population. This finding is consistent with small airway disease of parasitic origin. ii In adult horses the most likely cause is lungworm, Dictyocaulus arnfieldi. iii All the animals should be moved from the pasture when they have been treated with ivermectin per os at a dose rate of 200 +g/kg. D. arnfieldi larvae may survive on the pasture for some years and be able to infect animals the following season. The pasture should be cultivated or grazed by ruminants the following season. Tell the circus owner to treat his donkeys and mules with ivermectin!

89b

89c

89 i Septic arthritis of the tarsocrural joint. ii Lateromedial and dorsoplantar radiographs showed a lucent area of osteolysis in the medial malleolus of the distal tibia (89b) and a disruption of the normal bony architecture on the cranial aspect of the distal tibia (89c). Haematology showed a total WBC count of 19.9 × 109 cells/L (19,900 cells/+L), with 74% being neutrophils. There was a left shift and many of the neutrophils were showing degenerative toxic changes. The plasma fibrinogen was greater than 8 g/L (800 mg/dL). A sample of joint fluid was collected aseptically into an EDTA and a plain container. It was slightly turbid and did not string when drawn between thumb and forefinger. The sample collected into a plain container clotted after 15 minutes. The protein level within the synovial fluid was 35 g/L (3.5 g/dL) and there was a WBC count of 47.0 × 109 cells/L (47,000 cells/+L), 99% being neutrophils. There was no bacterial growth following culture of the joint fluid. iii Rest, antibiotics and flushing of the joint with several litres of saline. After flushing, inject antibiotic solution into the joint space. The foal was maintained on IV antibiotics for 10 days. The lameness improved dramatically following the joint irrigation but the swelling remained unchanged. The foal was confined with its dam to a stable during the period of treatment. A further 10 days of treatment with oral antibiotics, such as trimethoprim-sulphadiazine, was given. After 4 weeks confinement the foal was turned out into a small paddock. He made a full return to soundness with only minimal residual thickening of the tarsocrural joint.

86

90, 91: Questions 90a

90b

90 The perineal region of two different mares (90a, b). i Which conformational defect is common to each mare and how do they differ from each other? ii What is the significance of these differences in conformation? iii How might you relate the conformation to fertility? iv How may conformational abnormalities be corrected?

91 You are asked to examine a problem mare who is just coming into oestrus, with a view to determining the optimum time for insemination. Palpation of both ovaries suggests nothing obvious. Ultrasound examination of the left ovary is illustrated (91); the right ovary had follicles of up to 20 mm. You suggest the mare is inseminated the next day. Reexamination 3 days later reveals no change in the left ovary, either on palpation or ultrasound whilst the right ovary now has a 30 mm follicle. You advise it will be necessary to inseminate the mare again in 24 hours. What are three possible scenarios for your failure to give the best advice?

91

87

90, 91: Answers 90c

90 i Abnormal vulval conformation most prominent in 90b. In the normal mare (90c), the vulval lips are full and firm and meet evenly in the midline. In 90a there is 6 cm of vulval length dorsal to the pelvic floor and the vulval lips are angled at 25 degrees to the vertical. In 90b there is 6 cm of vulval length dorsal to the pelvic floor and the vulval lips are angled at 50 degrees to the vertical. ii Compromise of the normal vulval seal and development of a pneumovagina and the aspiration of bacteria and contaminated material. Furthermore, the pneumovagina may lead to a urovagina (urine pooling within the vagina). The more severe conformational abnormalities are more likely to result in failure of the vulval seal, and to increased faecal contamination since the vulva forms a shelf on to which faeces may collect. iii The development of a pneumovagina may result in vaginitis, cervicitis and possibly an endometritis. Contamination of the caudal reproductive tract with bacteria during pregnancy can result in embryonic death, and in late pregnancy can result in the development of a placentitis and lead to abortion. iv By increasing the physical condition and fat status of the mare. Surgery of the perineal region may be necessary, and three techniques have been described: Caslick vulvoplasty, episioplasty and perineal body transection. The choice of technique depends upon the age of the mare and the degree of perineal abnormality. 91 (1) It is not uncommon to find a large follicle present at the beginning of oestrus which has grown during dioestrus. These occasionally ovulate rapidly at the beginning of oestrus but normally regress allowing another follicle to grow and ovulate. Follicles in regression are often more difficult to palpate. (2) Occasionally ‘static’ follicles are found over long periods in an ovary whilst other follicles grow and ovulate. (3) In this particular case, the structure seen in the left ovary is not a follicle but a periovarian cyst or Hydatid of Morgagni. These structures lie close to but are not part of the ovary. Normally smaller and not noticed on ultrasound, occasionally a large cyst is seen which is also palpable as an ill-defined soft structure adjacent to the ovary. Such cysts are more frequently seen in draught mares but are of no clinical significance.

88

92, 93: Questions 92 During an endoscopic examination of the uterus of a 12-year-old mare with a history of subfertility, several structures are found (92a). i What are these structures? ii To what extent can these structures interfere with fertility in the mare? iii What is your therapy?

92a

93

93 A 30-hour-old colt foal was presented for examination (93). After a normal parturition, the foal had sucked and appeared alert. Mild colic signs had first appeared at about 26 hours of age along with repeated straining as if to defaecate. Only small amounts of hard meconium had been passed. Some gut sounds were present. i What is the most likely cause of the colic signs in this foal? ii What are your differential diagnoses? iii What is the course of the signs? iv What is your treatment plan for this foal?

89

92, 93: Answers 92 i Uterine cysts. ii The significance of uterine cysts is unclear, and often mares are pregnant despite having many cysts. Cysts can give rise to false early pregnancy diagnosis or the incorrect diagnosis of twin pregnancies during ultrasound scanning. During follow-up examinations, cysts do not increase in diameter, are relatively constant in their position and show no appearance of an embryo around 20–23 days of pregnancy. Thorough identification of them at the beginning of the breeding season minimises the chance of false pregnancy diagnoses. Large cysts may interfere with the mobility phase 92c of the conceptus and make the vesicle unable to prevent luteolysis. Later in pregnancy, the absorption of nutrients and the development of chorionic villi may be diminished in places of contact between cysts and fetal membranes, leading to an increased risk of embryonic death. iii The need for therapy for endometrial cysts is uncertain. Because of risks such as uterine haemorrhage, mechanical uterine curettage is rarely used. Larger cysts can be punctured using an endometrial biopsy apparatus or manually if the cervix allows passage of one hand. Chemical curettage has equivocable results: the cysts may disappear but scar tissue may form. An endoscope and a thermocautery method involving looping and subsequent burning of cysts (92b, c) is possible. Wounds after cautery appear to heal very quickly. After cauterisation prostaglandin F2_ should be given and the uterus lavaged with saline.

92b

93 i The foal is suffering bouts of acute colic due to RM. ii Ruptured bladder, enteritis, other causes of mechanical GI obstruction (atresia coli, entrapment or strangulated hernia), urethral/ureteral obstruction and rupture. iii Initially straining, but then progressing to typical acute colic signs with bouts of recumbency, rolling and lying on his back. Eventually the foal becomes exhausted, dehydrated and loses the desire to suck. iv Firm pellets of meconium compacting at the pelvic inlet can often be gently removed digitally. Regular warm water or liquid paraffin (200–300 ml) rectal enemas and retention enemas using acetylcysteine should be given until the meconium impaction resolves and normal orange/yellow digesta is passed. Repeated doses of warmed liquid paraffin (300 ml) or mineral oil via a nasogastric tube facilitate passage of the intestinal contents. The foal should be well hydrated intravenously with a balanced electrolyte solution until the meconium is passed. Oral electrolytes may be indicated if the meconium impaction persists. Oral anti-ulcer medication (sucralfate) and, occasionally, total parenteral nutrition may be indicated. Only very rarely, in severe/neglected cases, consider surgery.

90

94, 95: Questions 94a

94b

94 i What is this chorionic distortion (94a)? ii What is unusual about this everted placenta (94b)? iii What is the significance of this chorionic pallor near the cervical star (94c)?

94c

95 Dorsoproximal palmar distal 60° oblique radiographs of a 3-month-old Thoroughbred foal with an acquired flexor deformity (95). i What radiological changes are present? ii How do these changes relate to the flexor deformity and what do they suggest about its severity? iii What treatment is necessary and what is the long-term prognosis?

95

91

94, 95: Answers 94d

94e

94 i This chorionic bulge is likely to be caused by the presence of a large endometrial focal lesion, probably a cyst. ii The umbilical cord attachment site is anomalous, being located towards the floor of the uterus instead of the usual dorsal site (94d shows everted term placenta showing normal cord attachment site at the base of the pregnant horn, dorsally). It reflects an abnormal blastocyst implantation site. iii The chorion pallor around the cervical star reflects poor development of the villi, probably atrophic change (94e). Small areas of this are seen in many normal pregnancies and are considered insignificant. This is an unusually large area and might result in a slight reduction in fetal growth. 95 i There is evidence of severe remodelling of the dorsal tip of the third phalanx in both front feet of this foal. There are areas of complete and partial loss of bone density with changes in normal bone outline and a secondary vascular response. ii This foal had a stage 2 acquired flexor deformity of the distal interphalangeal joint (club foot) of at least a 30-day duration. The dorsal surface of the hoof wall was beyond the vertical and there was increased wear at the toe leading to hoof wall damage, separation at the white line, chronic infection and subsequently pedal bone damage. These changes decrease the prognosis which was already guarded due to the severity of the flexor deformity, and likely fibrosis, of the joint capsule and associated ligaments. iii The foal was treated with a bilateral inferior check ligament desmotomy and radical debridement of the chronically infected and damaged hoof wall. The toe was protected by a glue-on plastic shoe with toe extension and the heel of the foot vigorously lowered. The foal was weaned, placed on hay and a balanced mineral/trace element supplement and exercised in hand 3–4 times daily. The careful use of NSAIDs, with concommitant anti-ulcer medication, helped the foal to exercise more freely. The prognosis for such a severe flexor deformity is guarded to poor; however, in this particular case the response to surgery was rapid and the foal eventually achieved relatively normal foot conformation and soundness.

92

96–98: Questions 96

96 A month-old foal came in from the paddock with a laceration on the back of its left fore pastern (96). i What structures are involved? ii How would you treat this injury?

97

97 Two pieces of equipment used to assess motility of a semen sample (97). i What is the equipment? ii What procedures would you follow to obtain a suitable sample from raw semen? iii How would you judge motility in a semen sample? iv What would you describe as good motility for a semen sample from a 3year-old maiden stallion?

98

98 The uterine horn in cross-section on ultrasound (98). i What feature is most obvious? ii What is the significance of this? iii At what stage of the oestrous cycle do you think this ultrasonographic image was recorded?

93

96–98: Answers 96 i The toe is elevated without appreciable lowering of the fetlock. This indicates that the deep digital flexor tendon is severed without complete disruption of the superficial flexor tendon. In this region the tendon sheath will also be involved. ii Generally lacerations in this region are not amenable to suturing, as there is usually a ragged wound with heavy contamination. The best method of treatment is to debride carefully the area under general anaesthesia and to place the lower limb in a cast. Aggressive antibiotic therapy should be started. Conservative methods, such as bandaging and using a toe extension, are generally unsuccessful. If infection ascends the leg via the tendon sheath or via the tendons themselves, the prognosis is poor. 97 i A phase-contrast light microscope with a warming table at 37°C. This type of microscope allows good resolution and the warming table is necessary to maintain temperature. ii The raw semen should first be filtered (to remove the gel-fraction present) and then diluted. The amount of diluent depends on the initial concentration: the final concentration for optimal motility evaluation is 50 million spermatozoa per ml. A large enough droplet of diluted semen should be placed on a pre-warmed (to 37°C) slide and covered with a pre-warmed coverslip. iii The progressive motility should be assessed in at least 5 different places at ×150 magnification. It is important to make a judgement on the kind of movement the spermatozoa make. Not all spermatozoa that are moving show progressive motility: spermatozoa which only move in a tight circle are not of good quality and might have mid-piece defects. Progressive motility is when spermatozoa move rapidly across the field of vision. It is preferable to determine motility soon after collection. If motility is assessed on a sample of semen which has been cooled, it is important to pre-warm the semen to assess correctly the motility. iv When spermatozoa move quickly, mainly in a straight, forwards direction and the percentage of progressive motile spermatozoa is at least 65%. 98 i The endometrial folds. ii This usually indicates that the mare is in oestrus with high oestrogen and low or basal plasma progesterone levels. This feature can be induced in anoestrus by either injection of more than 2 mg oestradiol or by infusion of irritant solutions. Alternatively, intrauterine inoculation of a pathogen during mid or late dioestrus would produce a similar response due to acute inflammation. iii Maximal levels of oedema are usually seen in early to mid oestrus, e.g. 17/18 days after ovulation and decline 24 hours prior to ovulation. Such extremes of physiological oedema are rarely seen in the transitional phase between winter anoestrus and normal cycling.

94

99, 100: Questions 99 Preserved forage forms a large part of breeding animals’ feed and often its nutrient contribution is not known. i Why is it important to analyse a forage sample? ii How can a sample be analysed? iii In addition to nutrient quality, what should you consider in a sample of hay and how can it be assessed? iv What are the benefits and potential hazards of feeding haylage or silage on the breeding farm as the preserved forage source? 100a

Right artery

Left umbilical artery containing hypoechoic pus

100b Bladder

Left umbilical artery

100c Umbilical vein

Liver

Intestine

100 Transverse ultrasonographic images of the mid-ventral abdomen immediately caudal to the external remnant (100a), the caudoventral abdomen (100b) and the cranioventral abdomen (100c) from a 5-day-old foal which has shown signs of prematurity and septicaemia since birth. i Which umbilical structures should be present in each of these images? ii What do these images show? iii How would you treat this problem?

95

99, 100: Answers 99 i Forage, preserved and fresh as pasture, should form the basis of the diet for all animals at stud and the concentrate feed or supplements should be designed to complement that forage and supply the essential nutrients not provided in the forage. ii There are many commercial feedstuffs laboratories, using various acceptable analysis methods. iii The degree of respiratory challenge. If the dry matter was too low at baling, or the hay was stored badly, the level of contamination with fungal spores should be assessed with an air sampling machine and light microscope (×400). Most spores may not be pathogenic, but large numbers inhaled can predispose to or exacerbate respiratory disease. Some spores, such as Aspergillus spp. may be pathogenic. Hay with a high dry matter may still have a high degree of contamination with fungal spores as the ‘heat’ from the microbial activity can dry the hay, giving a false impression of the quality. iv Benefits are: (1) very low level of fungal spore contamination and low respiratory challenge; (2) the digestibility of semi-wilted haylage for horses is high; (3) haylage and silage made specifically for horses is packaged in convenient sizes and may be stored outside. Disadvantages are: (1) the fermentation quality is critical and must be checked. Poor fermentation may at best be unpalatable or cause mild scouring, but at worst may permit clostridial activity which can be fatal; (2) the nutrient specification can be higher than required by horses particularly if made originally for dairy or beef cattle. Nutrient levels should be checked before purchase; (3) the packaging is relatively fragile and must remain intact. If damaged, bales should be used within 3–4 days of the damage occurring. If the damage occurred at an unknown time, the bale should be discarded; (4) specialised handling equipment may be necessary for moving the large bales; (5) bales must be used within 3–4 days. 100 i Figure 100a: images immediately caudal to the external remnant are used to examine the umbilical arteries and urachus. Figure 100b: images of the caudoventral abdomen are used to examine the umbilical arteries as they branch to each side of the bladder. Figure 100c: images of the cranial abdomen are used to examine the umbilical vein. ii Figure 100a shows that the left umbilical artery (right of image) is slightly enlarged (normal diameter less than 1 cm), its wall is thickened and it contains hypoechoic material. The urachus is not visible which is normal. Figure 100b shows that the portion of the artery adjacent to the bladder has normal dimensions and 100c shows that the umbilical vein is normal. Thus, there is infection localised to one umbilical artery. iii Because the images show that the infection is mild and localised to one structure, this foal can be treated medically with IV antibiotics. A blood culture may help to identify the causative organism and appropriate antibiotic. The ultrasound examination should be repeated every 3 or 4 days to ensure that the condition is resolving. If repeated examinations demonstrate that there is no improvement, the antibiotic selection should be changed or surgical resection considered.

96

101–103: Questions 101 A retinal photograph of a bay, normal, 5-day-old Thoroughbred foal (101). i How would you describe the lesions in the tapetal fundus? ii What is their significance? iii Is any treatment necessary? iv What is their long-term affect on vision?

101

102 A Thoroughbred filly foal had developed normally up to 10 weeks of age and had been turned out with its dam each day. She then developed a slightly seedy toe in the left fore foot which required paring away and caused a slight lameness. Whilst this was being treated the left fore foot took on an upright conformation and rapidly became very ‘boxy’ (102). i What is your diagnosis? ii What conservative methods of treatment would you try? iii If conservative measures fail, what else can you do?

102

103 You are presented with a 3-day-old foal that was normal for the first 24 hours of age and then developed a variety of signs that included loss of affinity for its dam, loss of suckle reflex, prolonged sleep periods, bizarre behaviour (103), then an inability to stand and seizure activity. At first, the seizures were mild and infrequent, but they have now increased in frequency and intensity. i What is your most likely diagnosis? ii What is your therapeutic plan?

103

97

101–103: Answers 101 i There are many widespread, mauve, resolving, splash and punctate retinal haemorrhages in the green-blue tapetal fundus. They covered the whole of the tapetal fundus, but were concentrated in the area immediately above the optic disc as shown in this slide. Similar haemorrhages were present in the other eye. ii Retinal haemorrhage is a non-specific lesion that can be associated with inflammatory disease, retinal detachment, neoplasia, trauma, clotting disorders, chorioretinitis and other conditions. It has also been observed in foals suffering from NMS. Recently, research has shown that they are encountered in up to 16% of normal Thoroughbred foals and in the absence of any other ophthalmic or clinical abnormality. iii Retinal haemorrhages of the neonatal foal resolve spontaneously usually within the first 10 days of life. Resolution occurs first at the periphery of the fundus. Later the more centrally placed haemorrhages undergo resolution, as demonstrated in this slide, usually losing definition and changing colour from red to mauve. iv No long-term effect of neonatal retinal haemorrhages on any ophthalmic, visual or neurological parameter in the horse has ever been detected. 102 i Acquired flexural deformity of the distal interphalangeal joint. ii The initial treatment consisted of rasping the heels down each week. The mare and foal were confined to a large foaling box with limited bedding so that the foal walked on a firm surface. The mare was kept on a hay and water diet to reduce her milk production, thereby reducing the energy intake of the foal. iii If after 4–6 weeks of this regime little progress has been made, then the foal should be weaned and placed on a minimal ration. It should be left in a large stable with sparse bedding and have the heels lowered at weekly intervals. If after a further 2 weeks there has still been no improvement, then a desmotomy of the inferior check ligament should be carried out. Hand walking exercise for 20 minutes is started the day after surgery and continued for 10 days. At this time the stitches are removed and the foal turned out into a small paddock. The limb posture should improve rapidly within 2 weeks. Slight thickening may persist at the site of the desmotomy but a good prognosis for an athletic career can be expected. 103 i The history and clinical signs are typical of HIE (also known as NMS). A CSF tap may be indicated to rule out bacterial meningitis, particularly if any signs of sepsis are present, such as fever, diarrhoea, scleral vascular congestion or if there are derangements seen on CBC. ii (1) Seizure control: control of the seizures is of prime importance. For immediate suppression of signs, diazepam is useful at a dose between 5 and 20 mg IV. For control of seizures, IV phenobarbital is probably the drug of choice. A loading dose of 20 mg/kg infused IV is followed by 10 mg/kg every 12 hours. (2) Antibiotics: given the prolonged recumbency and often inadequate nutrition, prophylactic antimicrobial therapy is often instituted. This may be particularly important in a hospital environment where nosocomial infections are possible. (3) Nutrition is also critical and can often be successfully achieved by chronic placement of a nasogastric tube and regular feeding (every 1–2 hours). Some foals will develop intolerance to enteral feeding and may require total or partial parenteral nutrition. (4) Prophylactic antiulcer therapy is also recommended.

98

104–106: Questions 104a

104b

104 The normal anatomy of the uterus and ovaries (104a, b). i How does the uterus change during the oestrous cycle? ii What is the significance of the T-shaped uterus for ultrasound imaging? iii What are the two ligamentous structures which span between the ovary and the uterine horn? iv What is the significance of these two structures?

105 The uterine body in longitudinal section on ultrasound (105). i What two features are most obvious? ii Are these features physiological or pathological?

105

106 What are extenders used for the storage of stallion semen typically composed of?

99

104–106: Answers 104c

104 i During anoestrus the uterus is thin walled and flaccid and may be difficult to palpate per rectum. During oestrus the uterus enlarges and becomes oedematous (104c). It feels thicker, heavier and ‘doughy’ and is more easily palpable. The uterus becomes more tubular and tonic during dioestrus and is more readily palpated. ii The two uterine horns diverge sharply from the uterine body and the uterus normally assumes a T-shaped appearance. Ultrasonography produces images that are two-dimensional slices through a tissue. For the body of the uterus these slices are in a longitudinal plane, and the image therefore appears rectangular, whilst for the uterine horns the slices are in the transverse plane, and the images are circular. iii Between the caudal pole of the ovary and the tip of the uterine horn is the proper (or round) ligament of the ovary responsible for maintaining the association between the ovary and its respective uterine horn. The second, thinner ligamentous structure spans between the ovary and the uterine horn on the lateral aspect. This structure is called the tubal membrane since it contains the tortuous oviduct. iv The proper ligament of the ovary and the tubal membrane respectively form the medial and lateral borders of the ovarian bursa which contains the infundibulum and functions to assist passage of the ovum into the oviduct. 105 i Endometrial oedema and free luminal fluid. ii The oedema is usually physiologically normal (see 98). Free fluid is certainly not normal in dioestrus or early pregnancy, although in early oestrus, small collections of fluid are often seen. In some mares, e.g. older maiden mares, large pockets of anechoic fluid are sometimes seen. Accumulation of this fluid, which appears to be a transudate (no inflammatory products) rather than an exudate, may occur due to impaired cervical drainage. It is not known whether all mares produce some transudate but no accumulation occurs, or whether some mares produce much larger quantities of fluid which accumulate faster than drainage allows. In many cases, most if not all the fluid disappears nearing ovulation as cervical relaxation increases. Fluid is seen after mating but should disappear within 12 hours. Persistence of fluid after mating suggests persistent acute endometritis. Fluid persisting into mid dioestrus is often associated with acute bacterial endometritis and early luteal regression. The degree of echogenicity is directly related to the level of particulate matter in the fluid but not necessarily to the PMN or bacterial numbers. 106 Extenders based on either egg-yolk, skim milk or a combination of both are used. The extenders contain sugars, other nutrients and antibiotics to optimise the survival time of the spermatozoa. Extenders are buffers, with pH and osmolarity adjusted to the semen and the temperature of the extender should be the same as the ejaculate. Extenders are either stored as a dry powder in the freezer or made in large volumes and stored in the freezer in aliquots of 50 ml. The extender contains proteins and, therefore, has to be thawed slowly and at an adequate temperature, so denaturation does not take place. Extenders for freezing contain a cryoprotectant, such as glycerol, to protect the spermatozoa during freezing and thawing.

100

107, 108: Questions 107a

107b

107c

107d

107 The ultrasound images were obtained from a 5-day-old Thoroughbred colt with a 7.5 MHz sector scanner transducer containing a built-in fluid offset from the ventral abdominal window (107a–d). The foal was 2 weeks premature and had been comatose after birth but responded well to initial medical therapy. On day 5 of hospitalisation, the foal’s urine production decreased, gastric reflux was obtained, and the foal developed progressive abdominal distention and colic and became depressed. Physical examination revealed an elevated heart rate and decreased to absent GI sounds throughout the abdomen. i What are your differential diagnoses? ii What are the ultrasound findings? iii What is your diagnosis? iv What is your recommended treatment? v What is your prognosis?

108 A 7-year-old stallion is referred to your clinic because of a sudden lack of libido. The stallion has to cover approximately 70 mares naturally per breeding season. At the stud farm where he stands, he is used daily to tease all the mares. For the last two years the stallion has been competing regularly at showjumping competitions. What is your diagnosis and advice to the handler of the stallion?

101

107, 108: Answers 107 i They include small intestinal obstruction, most likely an intussusception. Other causes of small intestinal obstruction must be considered including a small intestinal volvulus, mesodiverticular band or other congenital abnormality causing small intestinal obstruction, intramural intestinal mass such as that caused by hypoxic bowel syndrome, atresia coli and other causes of small intestinal obstruction. ii Figures 107a–c reveal the classic target or bull’s eye signs found with an intussusception and turgid, distended loops of small intestine proximal to the obstruction. The wall of the intussusceptum and intussuscipiens (107b) is several times normal thickness and hypoechoic filmy strands (arrow) are imaged between the intussusceptum (curved arrow) and the intussuscipiens (large arrow) which represent fibrin strands (107c). The distended jejunum proximal to the obstruction has a normal (33 mm) or slightly thickened wall (107d). In real time, no peristaltic activity was detected in the intussusception or the distended small intestine proximal to the obstruction. There is a slight increase in the amount of free peritoneal fluid detected in the peritoneal cavity but it is anechoic and no adhesions are detected. iii The final diagnosis is a jejunal-jejunal intussusception with an ileus and distention of the small intestine proximal to the intussusception without vascular compromise of the jejunum proximal to the obstruction. iv This foal needs a ventral midline celiotomy with resection of the affected portions of jejunum and a small intestinal anastomosis. The foal should be supported with IV fluids, as needed, to correct dehydration and for maintenance therapy. Any co-existing acid-base and electrolyte abnormalities should be corrected with the IV fluid therapy and broad-spectrum antimicrobial therapy should be initiated. Medical treatment without surgical intervention is not indicated and will result in the demise of this foal. Routine post-operative colic management should follow the surgical repair. v The foal has a guarded prognosis which depends upon the length of small intestine involved in the intussusception and the viability of the adjacent small intestine. The small intestine proximal to the intussusception appears to be viable, because its wall thickness is normal or near normal, although an ileus is present. Therefore, an extensive small intestinal resection is unlikely to be needed if immediate surgical intervention is performed. Without surgery, the foal has a grave prognosis for life. 108 If there is no physical explanation for the lack of libido or a change of teaser mare, handler and environment, the diagnosis is likely to be libido problems due to a psychological problem of the stallion. The advice would be to change the management at the stud farm. Initially give the stallion one week of sexual rest and avoid teasing the mares with the stallion. After a week, providing his libido has returned, let the stallion breed by AI. This will mean that semen collection can be reduced to every other day. Veterinary examination of the mares including accurate palpation and ultrasonographic assessment of the ovaries and uterus, to try and only use one insemination per cycle should be instituted. Hopefully the use of semen and consequently the semen collections can be limited. In addition, you must be careful about administering any medication to the stallion in connection with his competition activities to avoid any risk of affecting his fertility.

102

109–111: Questions 109 i What is shown in the figure (109). ii Differentiate between an epidural and a spinal block? iii How would you carry out a caudal epidural block in a mare? iv What drug is most commonly used for such an epidural block? v What are the advantages and indications of an epidural block? vi What problems might occur with the use of an epidural block in a mare?

109

110 The owner of the gelding with two granulating masses on the glans penis (see 142) asks whether the concurrent painful passage of urine (stranguria) of his horse could be explained by the presence of the tumours. i What other cause was detected by careful inspection of the penis (110)? ii What would be your therapy if squamous cell carcinoma was confirmed?

110

111 Cells obtained on an endometrial smear from a mare in early oestrus stained with Pollack’s trichrome (111). i What are the majority of the cells? ii What does this indicate? iii Concurrent bacterial culture revealed a few colonies of Escherischia coli and no venereal pathogens. Is the mare suitable for breeding? iv What treatment would you recommend?

111

103

109–111: Answers 109 i The site of an epidural block. ii Epidural injection means injection of local anaesthetic into the epidural space, i.e. affecting the spinal nerves as they exit from the vertebral canal. A spinal block is injection into the subarachnoid space, i.e. into the CSF, and thus affects the spinal nerves and spinal cord. iii Identify the 1st and 2nd coccygeal vertebral space when raising the tail. A straight line between two coxofemoral joints joins the midline identifying the sacrococcygeal joint. The space between the first and second coccygeal vertebra is immediately caudal to this. Sterile skin preparation of the needle insertion site. Inject a small wheal of local anaesthetic solution. Introduce the needle at right angles to the croup or a 30 degree angle. Slow injection of calculated dose (over 1 minute). (Non-resistance to injection if in the right place.) The use of single dose vials reduces the risk of sepsis and a reduction in the chance of pieces of rubber being introduced into the CSF. If blood is obtained, withdraw the needle and clear it. If in the unlikely event that CSF fluid is obtained, either abandon the injection or inject 50–60% of the original dose as a spinal block. Allow time for the block to take its effect (15 minutes). iv Local anaesthetic (0.22 ml/kg over 1 minute): maximum dose of 10 ml of 2% lignocaine (lidocaine)solution per 450 kg horse should be administered. Analgesia will take place in approximately 15 minutes and lasts approximately 60 minutes. If adrenaline is used with the lignocaine, then up to 90 minutes can be expected. v (1) Excellent prolonged pain relief without the need for a general anaesthetic; (2) gynaecological operations on the anus, perineum and vulva. Suturing of wounds, operation of a prolapsed rectum and amputation of the tail are also possible under an epidural block; (3) it overcomes straining during manipulative correction of malpresented fetuses and partial embyotomy. vi (1) Unfamiliarity can lead to trauma to spinal cord/cauda equina; (2) solutions should be preservative free to avoid chemical irritation, inflammation and fibrosis; (3) severe ataxia is possible, but hypotension in equidae is only experienced if a cranial epidural block is placed; (4) accidental subarachnoid injection can lead to the block spreading further forwards and affecting the intercostal and phrenic nerves, leading to respiratory arrest; (5) considerable individual variation (breed and age); (6) adipose tissue and engorged venous plexuses may occlude the foramina thus allowing an epidural block to affect more cranial nerves; (7) risk of introducing infection leading to septic meningitis/myelitis; (8) paraesthesis (numbness/tingling) can occur as the block wears off which can then can lead to self-mutilation. 110 i A smegmolith in the urethral fossa. After removal of the smegmolith, the horse was able to pass urine freely and painlessly. ii Amputation of the glans penis. 111 i PMNs. ii The presence of PMNs indicates the presence of an acute endometritis. iii Due to the presence of acute endometritis, the mare is unlikely to conceive, and thus is not a suitable candidate for covering. As no venereal pathogens were isolated, she does not pose a venereal disease risk to the stallion. iv Treatment for acute endometritis with a course of intrauterine antibiotic irrigations. A soluble, non-residue forming, non-irritant intra-uterine antibiotic formulation should be chosen. A gynaecological examination should include assessment of the genitalia for the presence of predisposing factors, such as poor perineal conformation or cervical injury.

104

112–114: Questions 112

112 The permanent state of the penis of a horse (112). i What is your diagnosis? ii Which surgical treatment would you recommend? iii Is it possible to perform the operation in cases where the horse is a stallion?

113a

113 Ultrasound image of the uterine horn in cross-section of a mare which was mated and then ovulated 18 days previously (113a). i What features are visible? ii What is your diagnosis? iii What action would you take? iv What advice would you give to the owner?

114 A 4-week-old Thoroughbred foal is presented for assessment (114). i What is your diagnosis? ii What treatment is required?

114

105

112–114: Answers 112 i Paralysis or permanent prolapse of the penis. ii A penis retraction operation, e.g. Bolz operation. iii No, the Bolz operation may be carried out only if the horse is a gelding and, thus, a stallion should first be castrated, ideally at least one month before the retraction procedure. Subsequently, the operation should only be performed when all post-castration swelling and inflammatory reactions have subsided. 113b

113 i A 19 mm embryonic vesicle with surrounding stroma showing apparent oedema. ii The mare is pregnant with a vesicle which is small for age. Oedema around the vesicle is not unusual to see in normal 15–17-day pregnancies (113b). Oedema as late as 18 days is unusual and suggests the mare may be returning to oestrus. This would be confirmed by visible oedema throughout the uterus suggesting that luteal regression has occurred. Failure to visualise a CL supports this. iii If luteal regression is a possibility then immediate support with exogenous progesterone must be instituted. Plasma progesterone measurement would confirm the diagnosis but only retrospectively. Progesterone therapy must be continued until either: (1) pregnancy failure; (2) a new ovulation is detected; (3) a normal pregnancy is still present at 100 days after which placental progesterone will be sufficient for pregnancy maintenance; (4) an embryo proper cannot be seen by day 28. iv If luteal regression has occurred then conceptus loss may follow within the next 24 hours. If the institution of progesterone therapy is in time to prevent loss, then the vesicle may survive. However, because it is ‘small-for-age’ it may still fail. Often small-for-age vesicles fail to grow to more than 20 mm and they fail to grow an embryo but when an embryo does develop, it also is small. The whole pregnancy appears as if conception had occurred several days later. Such pregnancies usually fail at some stage. However, attempts should be made to at least temporarily ‘save’ the pregnancy, and to monitor its development as in some cases healthy foals result. In the case in 113a, treatment was not given, the mare was in oestrus the next day and the pregnancy had disappeared at the next examination. 114 i Bilateral carpal varus. This condition is much less common than carpal valgus. ii Conservative measures should be tried first. This should include drastically reducing the dietary intake of the mare in an attempt to decrease the milk production. Exercise should also be restricted to a cage or a barn. Two weeks of confinement led to a marked improvement in the condition in this foal, but the varus remained and surgery was carried out. This consisted of the placement of two titanium staples across the distal radial growth plate in each forelimb on the lateral aspect. The foal was allowed gentle exercise in a pen and the staples were left in situ until the limbs were straight. A good cosmetic result was obtained.

106

115–117: Questions 115

115 You attend a mare that foaled unexpectantly at only 305 days gestation after dripping milk for 15 days (115). The foal, which is now 8 hours of age, seems alert and vigorous and although obviously weak, can stand without assistance. The foal has a suckle reflex and the mare has a small amount of milk. Examination of the placenta reveals diffuse thickening and discoloration. The foal has physical features consistent with its gestational age, i.e. small body size, floppy ears, lax tendons, a domed forehead and a soft, silky haircoat. A CBC reveals a leucocytosis with a mature neutrophilia and hyperfibrinoginaemia. i What is your prognosis for the foal’s survival? ii How would you treat this foal?

116 A 12-year-old mare with a severe case of endometritis was inappropriately treated with an irritant solution. Uterine endoscopy was peformed to assist an accurate prognosis. i What is the best time to perform the endoscopy? ii Which structures are important to examine? iii What aftercare is required?

117 The owner of a newborn filly is concerned because the foal has not been seen to pass urine during the first 6 hours of its neonatal life. The foal stood within 30 minutes of birth and sucked from the mare within 1 hour. The filly is bright, alert and responsive and is not straining to urinate. Should the owner be concerned by the absence of urine?

107

115–117: Answers 115 i Despite obvious prematurity there is some optimism with regards to this foal. The suggestion of placentitis and an inflammatory leucogram suggest in utero stress. It is believed that in utero stress hastens maturity, particularly maturity of the respiratory tract. Conversely, a decreased leucocyte count and low fibrinogen would confer a much poorer prognosis for survival, despite any early vigour. ii Despite the promising start to life for this foal it should be considered to be a risk foal and requires intensive monitoring. Blood culture is indicated and broad-spectrum antimicrobial therapy is warranted prior to return of culture results. Attempt to isolate possible pathogens from the mare and placenta. Good-quality colostrum (SG >1.070) should be administered to foals less than 18 hours of age, or plasma infusion (2 litres) if older. The foal’s IgG concentration should be evaluated after treatment. Perhaps radiograph carpi and tarsi to check for ossification: if ossification is poor, reduce exercise and provide supportive splinting. 116a

116b

116 i During dioestrus, although uterine resistance to infection is diminished. The uterus has to be inflated, usually with air, and it is necessary to have a closed cervix. During oestrus, air will escape through the relaxed cervix making it difficult to inflate the uterus and a good inspection is impossible. ii The endometrium: in the normal uterus, it should be relatively easy to reach the tip of the horn in which the oviductal papilla should be clearly visible, slightly protruding into the lumen surrounded by normal (smooth and pink) endometrium (116a). In severe cases of endometritis(116b), the endometrial surface can be destroyed. Abnormal conformation of the uterus, adhesions and cysts are noted and if necessary treated. Using the endoscope as a guide, a biopsy sample from a specific place can be taken. On leaving the uterus the inflated air is removed by suction and the cervix inspected. iii The uterus should be flushed and the mare given prostaglandin F2_ immediately after the endoscopy to cause luteolysis. In the subsequent oestrus, endometrial swabs and smears are taken and the uterus treated as necessary. 117 No. It has been reported that the mean time to the first passage of urine in fillies is nearly 11 hours of age. The time is shorter in colts (6 hours).

108

118, 119: Questions 118 This mare (118) is exhibiting eversion of the vulvar lips and exposure of the clitoris. i What is the significance of this behavioural response? ii Which other behavioural criteria are useful for detecting oestrus in the mare? iii How reliable are behavioural responses of the mare when attempting to predict ovulation?

118

119a

119b

119 A 9-month-old Thoroughbred colt had become very upright in his hind pasterns without showing any lameness. He had been treated by a prolonged period of confinement to a small barn and a reduced plane of nutrition. However, the condition worsened and he was now at the stage where the hind fetlock joints were knuckling forwards (119a), especially the left hind. The foal was not lame but moved stiffly at the trot with a tendency to abduct the stifles during motion. On closer examination, both femoropatellar joint capsules were swollen (119b) and the foal resented palpation of these joints. Flexion of the hock and stifle joint in each leg caused lameness. i How would you investigate this further? ii What treatment would you recommend?

109

118, 119: Answers 118 i This is colloquially termed ‘winking’ and is commonly associated with oestrous behaviour. The response may also be seen in some mares during dioestrus and late pregnancy or, occasionally, even due to vulval irritation. The response is best assessed in the presence of a teaser stallion since some mares ‘show’ inappropriately to stimulation of the perineal region or due to environmental triggers. The response may differ if more than one stallion is used for teasing, and normally cycling mares are best teased daily with the same stallion. ii Winking, squatting, tail raising and urination. Failure to reject the stallion by absence of kicking response is also a useful assessment, although excessive biting by the stallion can result in dioestrous signs, such as kicking, striking and biting. iii They are not accurate measures of the time of ovulation. Fifty per cent of mares may exhibit oestral behavioural characteristics from 5 days before to 2 days after ovulation. There is not usually an immediate loss of behavioural response after ovulation, rejection of the stallion mirrors the rise in plasma progesterone concentration. This takes approximately 5 days to reach plateau values and during the first 48 hours some behavioural responses may be exhibited. 119c

119 i Lateromedial and caudocranial radiographs were taken of both stifles and hind fetlocks. The films revealed a deficit in the lateral trochlear ridge of the distal femur in the left stifle (119c). In the right stifle there was a slight subchondral lucency in the lateral trochlear ridge but no obvious radiographic deficit. These changes are characteristic of osteochondritis dissecans. The fetlocks showed no radiographic changes and their flexure was secondary to the pain arising from the stifles. ii Arthroscopic examination and curettage of the lesions was the treatment of choice. In the left stifle there was hypertrophy of the synovial villi and a large area of elevated, thickened and soft cartilage on the middle third of the lateral condyle. This was removed and the soft subchondral bone debrided. There were similar though less extensive lesions in the right femoropatellar joint despite the relatively slight radiographic changes. These were treated in the same way. The skin incisions were sutured and dusted with antibiotic powder. Post-operatively the foal was given antibiotics and NSAIDs daily for 5 days. By the second day following surgery the foal was moving comfortably, and the hind fetlock joints were adopting a more normal position. He was confined to a stable for 2 months after which he was gradually turned out into a paddock.

110

120, 121: Questions 120 Ultrasound image of a typical case of pyometra with uterine horns and body distended to a depth of 12 cm with a hypoechoic fluid (120a). i Define pyometra in the mare. ii What is the possible aetiology? iii What are the clinical signs? iv What clinical procedures would you undertake to confirm a diagnosis?

120a

121 A day-old Thoroughbred foal was born with this deformity (121). i What is this condition and what syndrome may it be a part of? ii What are the main complications in dealing with such foals? iii How would you treat the condition?

121

111

120, 121: Answers 120b

120 i Pyometra in the mare is not normally dependant upon a persistent CL as in the cow, although cases have been reported where the endometrium becomes so denuded that prostaglandin F2_ synthesis is insufficient to cause luteolysis. Mares with pyometra may be cyclic or anoestrus. Premature luteolysis may be seen associated with cases of relatively short duration. Recovery of Streptococcus zooepidemicus is usual although occasionally no bacteria are isolated. The volume of retained exudate may vary according to the degree of cervical patency; 30 litres has been recorded. A reasonable definition is ‘pyometra in the mare is the chronic accumulation of large volumes of exudate throughout the uterine horns and body often associated with impaired cervical relaxation’. ii Frequent reinfection of the uterus after mating may eventually lead to cervical stenosis (fibrosis) with reduced ability to evacuate exudate during oestrus. Pyometra can also arise following the mating and infection of old maiden and barren mares. iii Systemic signs of pyometra are unusual. Accumulation of toxic exudate following post partum complications should not be considered as pyometra. Oestrous behaviour is variable and often slight occasional or moderate intermittent vulval discharge (coincident with oestrus) is the only sign. iv Repeated ultrasound examinations which show persistent fluid accumulation regardless of the stage of cycle confirm the diagnosis of pyometra. Intrauterine swabs for bacteriology and cytology confirm the fluid is an exudate. Do not confuse a full bladder (120b) with pyometra. 121 i Wrynose which is a congenital deformity, usually of the upper jaw, where the rostral facial structures are deviated to a variable extent, from severe, as in this case, to a more subtle abnormality. In this relatively uncommon syndrome, there are a variety of combinations of congenital appendicular and axial skeletal contractures and curvatures in the affected foal. Some cases of wrynose are thought to be due to uterine malpositioning and compression of the fetus in the second half of the pregnancy. ii Maxillary–mandibular malocclusion is common, and in severe cases cleft palate may also occur. Although many foals suck normally, this particular foal did not and an indwelling naso-oesophageal tube was inserted. Due to the possibility of poor consumption of colostrum and aspiration of milk, secondary infections and bacterial septicaemias can occur. iii Mild deformities may resolve spontaneously with the growth of the foal. Other deformities present may be a factor in whether to treat the animal although these too may resolve with conservative treatment. If the deformity is severe, as in this case, then the likelihood of spontaneous recovery is poor and surgical treatment is indicated. The heritability of wrynose is unknown and there has to be doubt as to whether affected foals should be used in breeding programmes.

112

122, 123: Questions 122 An adult stallion has been suffering from colic for several hours. The pulse rate is 72/minute. The left inguinal-scrotal region appears swollen and the left testicle is cool and firm to the touch (122). i What is your tentative diagnosis? ii How would you confirm the diagnosis? iii What immediate procedures would you follow prior to any surgical procedure? iv What is your ultimate surgical treatment ?

122

123a

Spleen

Urachal abscess

Umbilical arteries

123b Pus encapsulated in the urachus

Bladder

123 Transverse (123a) and longitudinal (123b) ultrasonographic images of the caudal abdomen from a 2-month-old foal with swelling of the external remnant of the umbilicus, fever and depression. The swelling is hot and painful on palpation and cannot be reduced. i What are your differential diagnoses for swelling of the external remnant of the umbilicus? ii What do these images demonstrate? iii How would you treat this foal?

113

122, 123: Answers 122 i Left-sided incarcerated/strangulated inguinal herniation. ii By rectal examination. Palpation of the left vaginal ring will reveal small intestine entering the inguinal canal. iii Rectal examination to evaluate the degree of dilation of the proximal small intestine. A nasogastric tube must be inserted to evaluate gastric contents, and to decompress the stomach in the case of gastric overload. The skin turgor, mucous membrane colour, and capillary refill time are evaluated to assess the degree of dehydration. If possible, haematological examination is carried out for evaluation of the PCV. NSAIDs, such as flunixin meglumine, and broad-spectrum antibiotics are administered IV, as well as saline solutions in the case of severe dehydration. iv Inguinal herniorrhaphy. The testicle at the affected site has to be removed to make closure of the external inguinal ring possible, which is done to prevent recurrence of the herniation. As hereditary factors may play a role in the incidence of inguinal herniation, it is recommended to exclude the animal from further breeding, and for that reason simultaneous removal of the other testicle should be considered. 123 i Umbilical hernia and umbilical infection. ii The transverse image shows that there is an anechoic fluid-filled structure with a thick capsule in the mid-ventral abdomen. The umbilical arteries are visible and the spleen lies to the left. The longitudinal image demonstrates that there is an anechoic structure cranial to the bladder. These findings are consistent with an urachal abscess. iii In contrast to the foal in 100, in this foal the umbilical abscess should be removed surgically. The abscess is large and has a thick capsule which would make adequate antibiotic penetration unlikely and surgery reduces the risk of seeding of other structures. Surgery is indicated if there are multiple structures involved and/or if the affected structures are more than twice their normal size.

114

124–126: Questions 124 A 5-month-old foal is presented with bilateral hindlimb fetlock swelling (124). The foal is slightly lame, and the joints are warm. Radiography confirms physeal dysplasia (physitis). i What is the name of the complex of disease entities of which this condition is a part? ii What are its causes? iii How would you address the nutritional management of this foal?

124

125 A mare about 6 weeks after parturition (125a). i What is the cause of the atrophy of the left gluteal muscles? ii What is a common sign in less severe cases? iii What is your prognosis?

125a

126 A chorion from a 9-month-gestation abortion (126). The fetus was growth-retarded. What is this condition?

126

115

124–126: Answers 124 i DOD. ii Incorrect nutrition, poor or faulty conformation, muscle imbalance, compression of the growth plate which may inhibit endochondral ossification (perhaps arising from physeal trauma, as a result of excessive exercise on hard ground). Rapid growth rates are often given as a causative factor, and some suggest a heritable component. iii (1) over feeding energy, and to a lesser extent protein; (2) mineral and vitamin deficiencies; (3) mineral and vitamin excesses and imbalances. At five months, weaning should be considered as a primary objective, to allow a greater degree of control over nutrition. If the foal has been offered no supplementary food to date, this should be introduced over 7 days, and then the foal may be weaned. If the foal is already eating well, weaning should occur as soon as possible. If the condition is severe, foals as young as 12–14 weeks can be successfully weaned to help control the condition. 125b

125 i Paralysis of the gluteal nerve. During the process of birth the left gluteal nerve of the mare has been damaged. It is a rare complication caused by bruising of the nerve in the birth canal by a bony protuberance from the foal at the location where the nerve passes the ilium. It can happen even during an apparently easy birth process. It may lead to problems with standing up in some mares immediately after parturition. Some weeks after parturition the atrophy of the gluteal muscles becomes visible. ii Only the caudal part of the gluteal nerve (cutaneous branch) is damaged, leading to a constant sweating on a part of the buttock on the affected side (125b). iii The prognosis is favourable for both severe and mild cases. Usually there is full recovery after 3–6 months. 126 The chorion is a very abnormal shape, the horns being poorly developed and the body wider than normal. This is typical of a ‘body pregnancy’, the pathogenesis of which is not understood. Many cases have a longer than normal umbilical cord and some have limb contractures.

116

127–129: Questions 127 A 23-year-old mare, mated unsuccessfully for the last 2 years but not bred previously since a 3 year old, was examined for pregnancy 14 days after ovulation. i What features are seen in 127? ii What is your diagnosis? iii What advice would you offer the owner?

127

128a

128b

128 These two ovaries (128a, b) have single fluid-filled cysts on their surface. i What is the origin of these structures? ii What is their clinical significance? iii How common is cystic ovarian disease?

129 You decide to induce a mare at 342 days gestation because the dam has developed a severe, progressive and lifethreatening pulmonary disease. The induction went without complication, but it is noticed that the amniotic fluid and the foal are discoloured with an orange-brown fluid (129). i What is this fluid and why is it present? ii What is the most likely complication of this finding?

129

117

127–129: Answers 127 i Uterine oedema, free luminal fluid and an endometrial cyst. ii The mare is not in foal. She appears to be returning to oestrus earlier than expected, probably due to a uterine infection which can be confirmed by cytology (and bacteriology). The cyst is ‘normal’ for an aged mare. iii The mare will present a considerable problem to: (1) clear the uterine infection; (2) mate again without reinfection or significant fluid accumulation; (3) and because of age-related lowered pregnancy rate and increased pregnancy loss rate, she has a reduced chance of becoming pregnant and carrying a live foal to term. Unless the mare has particular economic or sentimental value, the owner would be well advised to consider whether further attempts to get her in foal are worthwhile. 128 i Neither of these cystic structures arise from the ovarian stroma. They are therefore not ovarian cysts. A broad definition of para-bursal cysts may be used; however, more accurately they are cysts of the mesosalpinx (128a) and mesovarium (128b). Similar fluid-filled cysts in the region of the ovulation fossa (fossal cysts), and small nodules located within the loose connective tissue covering of the ovary (adrenocortical nodules) have also been identified. ii No clinical significance in the majority of mares. They are not endocrinologically active and do not usually interfere with the process of ovulation or oocyte transport. Occasionally, large cysts may be palpated or imaged using ultrasonography, and may cause confusion with follicular structures. However, the lack of change in size or appearance of these structures is usually diagnostic. iii True cystic ovarian disease does not occur in the mare. The term implies fluidfilled structures within the ovarian stroma which are either abnormal or have developed in an abnormal manner. There are several situations when mares may be misdiagnosed as having ovarian cysts, including during vernal transition when a single or multiple large follicles may persist without ovulating, during prolonged dioestrus when follicular development is common and during pregnancy when there is marked ovarian activity. 129 i The fluid is meconium, a sterile concretion of intestinal cells and secretions that forms during gestation. Its presence in the amniotic fluid suggests that there has been some in utero stress that has resulted in premature defecation. ii Aspiration of meconium can result in airway plugging and act as a nidus for bacterial infection of the lower airway. The respiratory tract should be suctioned or drained in foals that are meconium stained at birth to reduce this possiblity. Prophylactic antibiotics are also strongly recommended.

118

130, 131: Questions 130a

130b

130 These two photographs of a mare’s vulva were taken two weeks apart (130a, b). i What is your diagnosis? ii What comment would you make about the person holding the tail? iii What is the typical course of the condition in the mare?

131 The left eye of a bay, underweight and dull, 14hour-old Thoroughbred foal (131a). i What do you see and postulate how it may have occurred? ii What complications are possible? iii How would you treat the case? iv How could it have been prevented?

131a

119

130, 131: Answers 130 i Equine coital exanthema caused by EHV-3. ii This is a sexually transmitted viral infection that can also be passively transferred via contaminated instruments or examination gloves. It is, therefore, important that the person holding the tail for the photograph should thoroughly clean and disinfect their hands before touching any other mares. Once a case of EHV-3 has been confirmed, gloves should be worn each time the lesions are inspected and changed after every examination. iii The first clinical signs appear about 5–7 days after initial infection (usually via sexual contact) as multiple small (2–3 mm) nodules on the vulva and adjoining skin. The nodules progress to vesicles that burst, eventually leaving a non-pigmented ulcer of about 5–8 mm. These ulcers heal in a period of about 2 weeks, sometimes leaving a small non-pigmented scar. Occasionally, there may be a transient depression and variable pyrexia. There is no effect on fertility in the mare although rarely the lesions may be sore enough to prevent coitus. 131b

131 i A foreign body consisting of strands of hair wound round into a tight coil and resting on the cornea. There is excessive lacrimation, especially from the nasal canthus, and matting together of the upper cilia. The condition was also present in the right eye. The bilateral distribution of the foreign body and its nature are unusual because most are of plant origin and unilateral. The foal was frequently recumbent and kept in a box where large amounts of adult horse hair were present. These must have entered the conjunctival sac whilst the foal was recumbent and wound themselves into a tight ring by globe and eyelid movement. ii The most likely complication is corneal damage ranging from corneal oedema to ulceration. The latter occurred in the right eye. Figure 131b shows the right eye immediately after removal of the hair foreign body. The resultant round, corneal ulcer is clearly visible in the centre of the cornea, just above the lower eyelid. The ulcer is accompanied by loss of corneal epithelium and stromal tissue, surrounding underrun epithelium and corneal oedema, superficial perilimbal neovascularisation, and positive uptake of fluorescein. Secondary bacterial, or occasionally fungal, infection could have further complicated the case. Severe loss of corneal tissue and/or infection can lead to hypopyon with a secondary bacterial uveitis, descemetocoele (herniation of Descemet’s membrane through a corneal stromal defect) and possible endophthalmitis. iii Removal of the foreign bodies as soon as possible using gentle manual restraint, local anaesthetic drops instilled into the conjunctival sacs and fine forceps. The conjuntival sacs should be carefully searched for further materials and lavaged with artificial tears. Antibiotic ophthalmic ointment may be necessary. iv Keep the foal on a clean surface, such as a foal bed. Regular examination of both eyes and the application of artificial tears to flush and moisten the conjuntiva and cornea are also helpful.

120

132, 133: Questions 132 You are presented with a 4-day-old Thoroughbred filly with a primary complaint of progressive lethargy and depression. On physical examination you detect pale, icteric mucous membranes (132a), tachycardia (200 beats/minute), tachypnoea (80 breaths/ minute) and mildly elevated rectal temperature (39°C). You note the passage of dark urine (132b). The foal has a PCV of 10%. i What are your differential diagnoses? ii What diagnostic tests can be performed to confirm your major differential diagnosis? iii What is your treatment for this foal? iv What blood types are most commonly associated with this condition? v How can this condition be prevented?

132a

133 A mare with a long history of infertility caused by chronic Klebsiella endometritis was succesfully treated and became pregnant. She aborted a 9-month fetus (133). i What do you notice about the appearance of the fetus? ii What three conditions could affect a fetus in this way? iii What do you notice about the appearance of the chorion? iv What is your diagnosis?

133

132b

121

132, 133: Answers 132 i (1) NI is the most likely diagnosis. Antibodies absorbed during colostral transfer result in RBC destruction and consequently a form of autoimmune haemolytic anaemia, haemoglobinaemia, haemoglobinuria and hyperbilirubinaemia. It is possible for low-grade elevations in rectal temperature to occur with NI. The rate of onset and severity of clinical signs vary depending on the rate and severity of RBC destruction, e.g. some foals can present with acute collapse. (2) Septicaemia: icterus can be a feature of septicaemia. Unlike foals with NI, anaemia is a rare finding in septicaemia. It is, however, not uncommon for foals with NI to become septicaemic because of poor nutrition and prolonged recumbency. (3) Iron toxicity: foals are born with a high serum iron concentration and have the ability to absorb iron from the GI tract with greater efficiency than that of adult horses. Consequently, the administration of iron to foals during the first few days of life can saturate normal iron transportation and storage mechanisms and result in fatal toxicity. (4) Leptospirosis: although rare, neonatal infection can result in anaemia and icterus. (5) Neonatal hyperbilirubinaemia. ii A direct Coomb’s test. Detection of anti-RBC antibodies in mare’s serum or colostrum is also supportive of a diagnosis of NI. iii This foal is severely affected (PCV 10%) and so replacement of compatible RBCs is required. The ideal source is the dam, but removal of the offending red cell antibody is critical. If it is not possible to use the dam’s RBCs, then finding a compatible donor may be difficult. Identification of a ‘universal’ donor (Aa- and Qa-negative and anti-Aa and anti-Qa negative) would be suitable for most clinical cases of NI. The selection of a gelding as a donor is based only on unlikely previous exposure to foreign red cell antigen and is not related to their red cell antigens. Consider broadspectrum antimicrobials as prophylaxis against sepsis. Fluid and caloric support should be provided and stress minimised. In less severe cases box rest to minimise stress, IV fluid and nutritional support may be sufficient. iv Aa and Qa. Aa and Qa negative mares bred to Aa or Qa positive stallions are at risk of becoming sensitised to the stallions’ RBC antigen and producing antibodies. In her next pregnancy, if the stallion again is positive for this antigen, the colostrum is enriched in antibodies directed against an antigen present on the foal’s RBCs. v Test mares for the red cell antigens Aa and Qa. Stallions can be tested for compatibility with mares. There are tests for NI-causing antibodies during late gestation and a cross-matching test (Jaundice Foal Agglutination Test) on the mare’s colostrum. Some stud managers assume the foal is at risk from a mare which has earlier produced an NI foal. In this case, foaling must be very carefully supervised and the dam’s colostrum withheld from the foal by muzzing for 36–48 hours. The foal shold initially be fed donor colostrum and then milk replacer. The foal’s IgG level should be checked at 18 hours of life. The mare must be thoroughly milked out regularly and the colostrum discarded. 133 i The fetus shows emaciation and growth retardation. ii Chronic undernutrition caused by placental insufficiency, as in twinning, infective placentitis and body pregnancy. iii There is underexpansion of the uterine horns, and longitudinal ridges down the horns. Villous development is poor. (There was no evidence of an infective placentitis.) iv As the villous surface of the chorion reflects the morphology of the endometrium during pregnancy, this mare’s history and the fetoplacental pathology are strongly indicative of profound residual uterine scarring following the Klebsiella infection.

122

134, 135: Questions 134 A bacterial isolate cultured from a mare’s clitoris prior to mating (134). The plate shows the organism in pure culture after overnight incubation on MacConkey’s agar under aerobic culture. There is a luxuriant growth of wet/mucoid pink colonies. i On the basis of its gross appearance, what important organism could this be? ii Is it a venereal pathogen? iii What further tests should be performed to clarify its pathogenicity? iv What treatment do you recommend? v What treatment may be used to help prevent recurrence of the infection? vi What management procedures are thought to predispose to the establishment of this infection?

134

135a

135b

135 Ultrasonographic views of the right uterine horn of an 18-year-old Thoroughbred mare (135a, b), known to have had two previous twin pregnancies, and examined for the first time 20 days after mating. i What features are seen? ii What is your diagnosis? iii How would you attempt to confirm your diagnosis? iv What action would you take?

123

134, 135: Answers 134 i From the gross appearance the organism is likely to be Klebsiella pneumoniae. (Note: Enterobacter aerogenes has a very similar gross appearance on MacConkey agar, and the two should be differentiated by their biochemical profile.) ii Certain strains of K. pneumoniae have been associated with outbreaks of true venereal disease. iii Capsule typing should be performed to classify the organism. Only capsule types 1, 2 and 5 have been associated with outbreaks of venereal disease. iv The clitoris should be treated by repeated thorough scrubbing of the sinuses and fossa (using a surgical scrub) to remove smegma, and packing with specific antibiotic cream according to sensitivity testing. In intractable cases clitorectomy may be indicated. v Application of a broth of normal perineal bacteria may help to re-establish the normal flora and provide biological competition to the re-establishment of the infection. vi It is thought that routine washing of the perineum with certain antiseptic solutions predisposes to the establishment of K. pneumoniae and Pseudomonas aeruginosa infections by removing the more susceptible normal flora. 135c

135 i Two fluid-filled structures, one spherical and the other irregular in shape. ii Possible unilateral twin vesicles of approximately 20 and 16 days, or a single pregnancy and a 19 mm cyst, or a cyst with adjacent free fluid, or a 19 mm conceptus with adjacent free fluid. iii (1) Attempt to crush both structures. This would give you a definite diagnosis, namely, twins (nothing left); single pregnancy (cyst left); cyst plus fluid (fluid redistributed into horn and body). This route to a diagnosis is not to be recommended. (2) Search both structures for an embryo proper. This can only be positively identified by a visible heart beat. (3) Look closely at the wall between the two structures. It is relatively thick and hyperechoic when compared with the twin vesicle shown in 135c. This would confirm that at least one structure is a cyst. Reassessment of the irregular structure will confirm that the fluid is contained and does not extend up or down the horn as would be found with free fluid. iv Take no action at present but re-examine the mare in a few days to confirm your diagnosis of a cyst and single pregnancy by the presence of a single embryo.

124

136, 137: Questions 136 A 4-month-old foal sustained a wound to its right stifle one week ago. Over the last 48 hours the foal has developed a stilted gait and seemed unwilling to feed from the ground as usual. It has a high tail carriage and, when menaced, the response shown is initiated (136). i What is your clinical diagnosis and what prognosis would you give the foal? ii What factors may have led to the foal being susceptible to this disease? iii What treatment should you institute? iv What would you recommend as routine stud farm management for the prevention of this disease?

136

137a

137b

137 i For what disease control is this the sampling method in the stallion (137a–c)? ii How are the swab samples processed following collection? iii What are the clinical signs of this disease in the stallion? iv What treatment would you advise for an affected stallion?

137c

125

136, 137: Answers 136 i Tetanus. With a slow onset of clinical signs, appropriate aggressive therapy and no rapid deterioration, the foal has about a 50% chance of survival. ii (1) Inadequate vaccination of dam with failure to give a tetanus toxoid ‘booster’ 1–3 months prior to parturition. (2) Failure to recognise the above and hence administer tetanus antitoxin at birth and 3–6 weeks later would lead to inadequate passive immunity. (3) Failure of passive transfer at birth without checking the tetanus status of a colostrum or plasma donor. (4) Waning of passively derived tetanus antibodies prior to initial vaccination. iii (1) Penicillin therapy; initially sodium benzyl penicillin IV four times over the first day of treatment followed by procaine penicillin IM twice daily. (2) Tetanus antitoxin 20,000 IU IM for 3–5 days to neutralise unbound toxin. (3) Acetylpromazine or a combination of diazepam and xylazine to relieve muscle spasms and provide sedation. (4) Provision of a quiet, dark environment with soft but firm bedding, e.g. peat. (5) IV fluid therapy and nutritional. (6) Recognition of when prognosis becomes hopeless to allow speedy euthanasia. iv Ensure mares are fully vaccinated and receive annual boosters 1–3 months prior to foaling. If in doubt, administer tetanus antitoxin to the foal at birth and repeat 4 weeks later. Administer tetanus toxoid at 3–4 months of age, again 4 weeks later and repeat annually. 137 i CEMO (Taylorella equigenitalis). Regulations in certain countries for the control of this organism recommend that two sets of swabs are taken from every stallion before the start of the breeding season, 7 days apart. In addition to the sites illustrated (penile sheath, urethral fossa and urethra) a sample of pre-ejaculatory fluid can be taken. ii T. equigenitalis is a Gram-negative bacteria which requires a low oxygen concentration during culture. For this reason the swabs have to be placed immediately into a special charcoal transport medium (Amies), labelled with the name of the stallion and the site of collection and sent immediately to the bacteriological laboratory. The swabs should be inoculated on to two plates containing chocolate blood agar, one plate with streptomycin and one plate without. The samples are incubated microaerophilically and examined at 2, 3, 4 and 6 days. A result cannot be given earlier because of the slow growth of the bacteria. iii The disease usually causes no clinical signs in the stallion. iv Treatment for the stallion consists of thorough cleansing of the prepuce, penile sheath and fossa with a mild soap to remove smegma. This is followed by application of a solution of chlorhexidine (2%) and a cream containing 0.2% nitrofurazone for 3 consecutive days. Following treatment, three negative sets of swabs at weekly intervals, beginning at least 7 days after the last treatment, are used as the criteria for resolution of the disease in stallions. The stallion should also be test mated to at least 3 mares.

126

138, 139: Questions 138a

138b

138 i What is the most obvious clinical sign in this pony (138a, b)? ii What disease syndrome is this clinical sign highly suggestive of? iii What other clinical signs would you expect to find in this pony? iv How old would you expect this pony to be? v What specific test would you recommend to confirm your diagnosis? vi What treatment would you suggest? 139a

139b

139 A 20-day-old foal presents because of a lameness in the left rear limb of 6 days duration. There is obvious distension of the left tibiotarsal joint (139a). A CBC revealed leucocytosis (23 × 10 9 cells/L (23,000 cells/+L)) with mature neutrophilia. Fibrinogen was 8 g/L (800 mg/dL). Ultrasound examination of the umbilicus was normal. i What further diagnostic tests are indicated? ii Fluid from the left tibiotarsal joint had 58 × 109 cells/L (58,000 cells/+L) with 92% neutrophils. No bacteria were seen (139b). What is the significance of this finding? iii What therapy would you recommend?

127

138, 139: Answers 138c

138 i An excessively long and curly hair coat (hirsutism). ii Cushing’s syndrome (hyperadrenocorticism). iii Excessive sweating (hyperhydrosis), laminitis, bulging of supra-orbital fat (138c), lethargy/dullness, chronic infections, delayed wound healing, subfertility and blindness. Cushing’s syndrome in equids is almost always associated with an adenoma of the intermediate lobe of the pituitary gland and the polyuria and polydipsia often seen are due to secondary diabetes mellitus or inspidus. iv The average age of equids with Cushing’s syndrome is approximately 20 years and the condition is rare in young (less than 10 years old) animals. v The dexamethasone suppression test is widely used, but has the risk of inducing laminitis in the animal. Cortisol assay using the ACTH-stimulation test has a reduced risk of exacerbating or causing a laminitic condition and would be preferable. Cortisol assay before and after administration of thyroid releasing hormone is also used. vi Supportive measures, such as ensuring adequate nutritional intake. Drug therapy is based on the use of dopamine agonists such as bromocriptine or pergolide. These drugs seem to offer a reasonable likelihood of achieving a clinical improvement in the condition of affected animals. Recently, a serotonin antagonist, cyproheptadine, has also been successfully used. 139 i Arthrocentesis and radiography of the left hock are both indicated. Fluid from the joint should be submitted for cytology, Gram stain and bacterial culture. ii These findings are consistent with septic synovitis. An absence of bacteria on routine cytology should not preclude a diagnosis of bacterial joint infection. A positive culture can be enhanced by either placing the joint fluid into blood culture media or by centrifuging the sample and culturing the cellular pellet. iii Most clinicians would elect to perform joint lavage with saline. The use of an arthroscope allows for direct inspection of the joint surface and may enhance removal of fibrin during lavage. Lavages may need to be repeated and closed suction drainage should be considered for joints that are difficult to resolve. Broad-spectrum antibiotics and NSAIDs are also indicated. Infected umbilical remnants, if present, may require surgical removal.

128

140, 141: Questions 140 An 8-year-old multiparous mare is presented (140), 4 hours post-partum. i What possible structures could be present? ii What restraint can be used for successful and safe treatment? iii How would you treat each condition? iv What complications can arise? v What is your prognosis for future breeding?

140

141 A 12-year-old mare was diagnosed pregnant at 30 days. No subsequent signs of oestrus were seen, but 2 months later the mare was found to be no longer pregnant. Because of a poor breeding history, uterine endoscopic examination was performed and several structures were found (141). i What are the structures? ii How do they influence cycling activity of the mare? iii Can such a mare become pregnant whilst producing eCG?

141

129

140, 141: Answers 140 i (1) placenta; (2) uterus; (3) bladder; (4) small intestine or small colon; (5) blood clot within the prolapsed uterus. ii Care in selection of tranquillisers as the mare may already have low blood pressure; the use of stocks, hay bales and a low stable door must be assessed for prevention of injury to the operator and/or mare if an unexpected reaction by the mare occurs. iii (1) In some cases, the placenta can be removed manually by gentle massage; an inability to remove it without haemorrhage may indicate that both the placenta and uterus may have to be replaced into the abdominal cavity. (2) Palpate the uterus for tears, presence of the bladder, small intestine, small colon or blood clot, which may prevent replacement of the prolapse. iv (1) A ruptured or torn uterus due to the mare kicking the prolapse; (2) severe haemorrhage from the placenta being torn off or from the mare galloping and kicking at the prolapse; (3) if the bladder is prolapsed, the mare may be unable to urinate and so may strain heavily; drain the bladder before it is returned; (4) where bowel loops are suspected, these may be returned to the abdominal cavity without opening the dorsal portion of the prolapsed vagina; standing the mare with the hind quarters elevated greatly assists in the replacement of bowel loops if present, but more importantly, helps replacement of the prolapsed uterus. v The prognosis is good for a simple prolapse with retained placenta. Severe prolapses can cause tearing of ovarian attachments, which may cause physical injury and blockage of oocyte transport from the ovary. Haemorrhage, tearing and scarring of the uterus and tearing of the cervix all contribute to a less favourable prognosis; careful treatment and nursing can reduce these factors substantially. 141 i Endometrial cups. ii Endometrial cups produce eCG, which stimulates the primary CL and causes induced secondary follicles to ovulate and/or luteinise. Because progesterone production remains high, mares do not show signs of oestrus at the time of these secondary ovulations. eCG production is independent from the presence of a fetus and so once the endometrial cups are formed, eCG production will proceed even in cases in which embryonic/fetal loss occurs. At about day 100–140 of the pregnancy, normal cycling activity starts again in those cases of embryonic loss; in most cases this results in a decision not to mate the mare that season which could represent a serious economic loss. iii Current thinking is that the chances are very small that mares producing eCG can become pregnant. No practical therapy can shorten the lifetime of the endometrial cups. Surgical removal including video-endoscopic laser has been documented, but is not applicable in the clinical situation. Neither is there a satisfactory method for reducing levels of eCG (even though luteolysis can be induced by repeated (3–5) daily injections of prostaglandin F2_.) In non-cycling mares after (suspected) embryonic loss, determination of blood eCG levels is advisable to confirm the existence of active endometrial cups.

130

142–144: Questions 142

143

142 A 15-year-old gelding regularly drips some blood from the preputial orifice. By inspection of the penis, two granulating masses are found on the glans penis (142). i How would you make inspection of the penis possible? ii What is a rare, but serious complication of use of these drugs? iii What would be your likely diagnosis? iv What should be examined further?

143 A new-born foal has bilateral angular deformity of its hind legs (143). i What is the nature of these deformities? ii How should they be treated? iii What is the prognosis for flat racing?

144 A close-up view of a mare’s endometrium (144). i What are the important structures shown and what was the likely stage of gestation of the mare? ii What is their gross appearance and location? iii Are they found in the placenta at term?

144

131

142–144: Answers 142 i By systemic administration of tranquillisers, such as acetylpromazine, xylazine or detomidine. ii The possibility of the horse being unable to retract his penis following use of these drugs. iii Probably a squamous cell carcinoma, to be confirmed by biopsy. iv Careful inspection of the total penis and preputial folds; the inguinal lymph nodes should be palpated and X-rays of the lungs should be taken to detect metastasis. 143 i The left hind leg has a varal angulation of the tarsometatarsal joint and fetlock The right hind leg has a valgus angulation of the tibiotarsal joint and fetlock with marked outward rotation of the distal limb. The pelvis appears tilted and the foal walks with a weak, twisting action wearing down the edges of its hind feet. These deformities probably arise from in utero moulding. There is muscular, tendinous and ligamentous weakness allowing some lateromedial movement and angulation. ii This foal will benefit from exercise in a paddock with its dam. It will strengthen and the angulation improve quickly. When it is 10–14 days old it should be reassessed and if angulation is still present, the feet should be trimmed correctively, paring down the unworn inside of the left hind foot and the outer side of the right hind foot. Most cases achieve a good or acceptable conformation within one month, but in dysmature or premature foals incomplete calcification of tarsal bones and epiphyseal compression can lead to a permanent deformity. If the varal angulation persists beyond 3 weeks, then surgery must be undertaken. This can consist of growth acceleration by periosteal elevation or, alternatively, growth can be retarded on the open or convex side using screws and wires or staples, which remain in situ until the joint has straightened. If the varus persists at the tarsometatarsal level, the angulation will gradually improve with corrective hoof trimming over some months but a curby hocked conformation may persist. It is rare for tarsal valgus to persist or to be so severe that surgery is necessary. iii Good, even if surgery is necessary. 144 i The structures are mature endometrial cups. The mare was likely to be between 50 and 100 days of gestation. ii Endometrial cups are irregular in shape and vary tremendously in size from 1 cm in diameter, to as long as 5–10 cm. Note the honey-like material present in the depression of the cups; this material is a mixture of debris and secretion of the endometrial glands and cups. The cups are arranged in a circle at the base of the gravid uterine horn. iii No, by about day 130 sloughing of the cups is usually complete. The debris from the sloughing of the cup may become enclosed in the allantochorion, forming the allantochorionic pouches which can be up to 2 cm long. These pouches can occasionally be present in the placenta at term.

132

145–147: Questions 145 The mare illustrated (145) is presented to you 4 hours after foaling. The owner is worried about the fact that she has not yet expelled her placenta. i What is the usual post-partum time interval for placental expulsion? ii What can be the sequelae of a retained placenta? iii How would you treat this condition and what is the prognosis?

145

146 The day after induction of parturition, a foal with suspected meconium aspiration develops a fever and some abnormal findings on auscultation of the lung fields. The thorax is radiographed in order to characterise the abnormal findings (146). What is the distribution and possible origins of the changes present?

146

147 A 2-day-old Thoroughbred foal was found with a warm, swollen and slightly painful hock with an area oozing serum on the lateral aspect of the hock (147). i What is your diagnosis? ii How has it occurred? iii What treatment is required?

147

133

145–147: Answers 145 i The average time needed for placental expulsion is about 1 hour and should not take more than 2 hours. However, there is controversy with respect to the time interval in this definition and recognition of the precise time at which the process has become pathological is difficult. ii Draught horses have proven to be much more sensitive for serious sequelae compared with ponies and riding horses. Complications include acute metritis, septicaemia, laminitis and even death, so retained placenta should be treated as an emergency. iii The placenta should initially be tied up. As uterine contractility plays an important role in the dehiscence of the fetal membranes, oxytocin is recommended as a first and many times (up to 90% of cases) successful treatment. It is a good rule not to wait longer than 6 hours after parturition (depending on the case history or in heavy breeds earlier is preferable) before such treatment is started. This treatment avoids manipulation in the uterus with the risk of introducing micro-organisms. Oxytocin can be given IM (20–40 IU), which can be repeated after 1 hour if the placenta has not been passed. Alternatively, use slow IV infusion of 50 IU oxytocin in 1 litre of saline over 1 hour. Only if this treatment fails and the placenta is almost detached but retained within the uterus should one attempt gentle manual removal. Manual removal is hazardous as side-effects include retention of microvilli in the endometrium, serious haemorrhage and invagination of one of the horns. Occasionally, placement of 10 litres of warm saline or 1% povidone iodine solution inside the allantoic cavity to stretch the uterine wall and stimulate uterine contractions via endogenous oxytocin may assist separation of villi from their endometrial crypts. After removal, it is always important to check the placental membranes for completeness confirming that all the allantochorion has been removed and, if necessary, the uterus should be flushed and siphoned. Aftercare includes (depending on the severity of the case) regular general examination, checking the uterus (for involution and contents) and, if indicated, flushing and siphoning the uterus once or twice daily for a few days in combination with further injections of oxytocin. Special attention is paid for signs of laminitis and NSAIDs are given where laminitis is a suspected complication. Tetanus prophylaxis is recommended where appropriate and, if indicated, treatment with broad-spectrum antibiotics (systemic and intrauterine). Provided treatment is begun at the correct time and no secondary complications develop, the prognosis is good. 146 This foal has a moderate interstitial pattern that is predominately located in the dorsocaudal areas of the lungs. The changes are still consistent with the diagnosis of meconium aspiration. The distribution suggests that the aspiration may have occurred when the foal was lying on its back in utero. 147 i A bed sore. ii These occur when the foal struggles to rise from a poorly bedded floor. They can also arise on the lateral aspect of the stifle, elbow, carpus or fetlocks. A local cellulitis will develop and an elongated area of skin may slough off. An abscess may develop but septic arthritis or tenosynovitis are very rare complications. A linear scar usually results. iii The area should be washed and dressed daily, and if the cellulitis is marked a course of systemic antibiotics should be started. Above all the bedding should be kept plentiful and clean.

134

148, 149: Questions 148 i What is your diagnosis of this rare condition (148)? ii Can the condition vary in degree? iii When is a mare most at risk of this condition? iv What is your prognosis?

148

149 A 15-year-old multiparous Thoroughbred mare is presented with a tumour on her external genitalia (149). i What types of tumours commonly involve the external genitalia of mares? ii How would you establish a diagnosis? iii What types of treatment are available? iv How would you treat this particular case? v What is your prognosis?

149

135

148, 149: Answers 148 i Severe rectal prolapse complicated by prolapse of the intestines, through a tear in the rectum. ii The condition can vary from rectal prolapse of only a few centimetres through to the extensive prolapse illustrated here. Any prolapse is serious. iii During dystocia when intra-abdominal pressure can rise to high levels and cause the rectum to be expelled. iv In a severe case, euthanasia is the only option. Where there is only a few centimetres of rectum prolapsed, after delivery of the foal and an epidural injection, the rectum should be carefully cleaned and replaced. Appropriate antibiotic, anti-inflammatory and fluid therapy should be instituted. However, the prognosis depends on the trauma already suffered by the rectum and its ligamentous attachments, and the owner should be warned that the condition is very serious. Stretching of the mesentery can result in infarction of the terminal colon and the mare’s condition may deteriorate over the next 48 hours as the affected bowel becomes atonic, necessitating euthanasia. 149 i Squamous cell carcinoma, melanoma, melanosarcoma and sarcoid. ii Either a complete biopsy or a section biopsy for histopathological investigation. iii (1) Complete surgical excision: place the horse in stocks; tranquillise and give an epidural. Excise the tumour, ligate bleeders and close the wound. (2) Cryosurgical therapy: use cryotherapy unit which delivers nitrogen spray to the tumour surface. If possible, tumours should be debulked prior to freezing; use the freeze-thaw cycle at least twice after treatment and until slough of the tumour occurs. (3) Electrocautery: the use of electrocautery is an option. While the same tranquilliser anaesthetic technique can be used, the use of general anaesthetic is advised for such treatment. The tumour is removed with at least 5–10 mm of normal tissue as well; suturing may not be possible. (4) Radiation therapy: where the facility is available, the use of cobalt 60 or iridium 192 also gives good results. This should be done in conjunction with a specialist radiologist. This procedure requires isolation facilities and usually a general anaesthetic to insert and remove radioactive wires and rods. iv Surgical excision with removal of the entire tumour and at least 10 mm of the normal tissue around the base of the tumour. v Excellent provided a generous portion of normal tissue has been removed and shows no evidence of tumour invasion.

136

150, 151: Questions 150a

150b

150 i What are the two types of containers illustrated (150a, b) and how do they work? ii What are the procedures involved in preparing stallion semen for transport? iii Which container would you use for semen to be used within 3 hours of collection?

151a

151b

151 These ultrasound images were obtained from an 8-year-old Appaloosa mare with a 2.5 and 7.5 MHz sector scanner transducer from the ventral abdominal window at 304 days gestation (151a–c). The mare had a history of premature udder development and premature lactation. No other problems were noticed with the pregnancy. i What are the ultrasound findings? ii What is your diagnosis and prognosis?

151c

137

150, 151: Answers 150 i The containers are used to transport chilled semen. The one in 150a consists of a polystyrene box, in which two 15 ml tubes with chilled semen can be placed. The polystyrene box is packed in a cardboard box which can be placed in a refrigerated (at 5°C) transporter. This is an efficient and inexpensive system. The container in 150b is the Hamilton-Thorn Equitainer System (Equitainer©). This consists of a strong container with a snap-lock containing frozen canisters, insulation, thermal ballast bags and an isothermaliser. The semen is extended and placed in bags and placed in the Equitainer, which cools the semen at the appropriate cooling rate to 5°C. The Equitainer is easy to use, strong and works very well. ii To process semen the following procedure should be followed swiftly and precisely, preferably in a clean, laboratory-type environment and everything that is used for each particular stallion should be clearly labelled for that stallion. After collection, the ejaculate is filtered through gauze if a filter was not used during the collection process. Semen which has to be inseminated immediately can be used undiluted, but if the semen is to be used after 10 minutes it is best diluted. If semen is stored for between 2 hours and 6 hours, removing the seminal plasma by centrifugation (900xG at room temperature), thereby delaying the process of sperm capacitation, may be beneficial for certain stallions. To prevent too much energy loss of the spermatozoa cooling of the semen is required when semen is used more than 6 hours after collection. The gel-free ejaculate is diluted with a suitable extender at 37°C. Motility is checked using a microscope with a warming table at 37°C. Each shipment of fresh or chilled semen has to be accompanied by documents with information on the stallion, the collection centre, collection date, shipment date and information about the semen quality and the number of sperm sent. iii Probably neither. If mares are to be inseminated with semen within 3 hours of collection, adding extender and keeping the semen at room temperature (18–22°C) in a light-proof, air-tight container is satisfactory. 151 i Figure 151a reveals a single fetus in anterior presentation normal sized for this stage of gestation with an aortic diameter of 2.28 cm. A resting fetal heart rate of 65 beats/minute (151b) is also appropriate for this stage of gestation. There was minimal fetal movement detected. There is little or no visible allantoic or amniotic fluid surrounding the fetal neck (151c) and the fetal membranes (small arrow) are folded around the fetus (large arrow). The uteroplacental thickness exceeds 2 cm in many areas due to the folding of the fetal membranes. No areas of uteroplacental separation are detected. Notice the dramatic folding of the amnion and chorioallantois between the fetal neck and thorax due to the near complete absence of fetal fluids surrounding the fetus. ii The most likely diagnosis is that the fetus is experiencing chronic intrauterine hypoxia associated with placental insufficiency. Chronic intrauterine hypoxia may result in oligohydramnios and oligohydroallantois. Rupture of the fetal membranes is a possible but less likely cause of the fetal fluid loss. The prognosis is guarded. The near complete absence of fetal fluids places the fetus at high risk for crimping of the umbilical cord and abnormal blood flow to the fetus. Decreased fetal fluids are most frequently associated with chronic intrauterine hypoxia and, therefore, the fetus is at high risk for NMS. Pulmonary immaturity occurs when there is inadequate fluid surrounding the fetus during late gestation. The foal is likely to have a low biophysical profile score.

138

152, 153: Questions 152 Examination of a 3-month-old colt showing signs of depression, a cough and a purulent nasal discharge reveals pyrexia, tachycardia, tachypnoea and bilateral adventitious respiratory sounds on thoracic auscultation. A standing lateral thoracic radiograph is shown (152). You elect to treat the foal orally with a combination of erythromycin and rifampicin for 30 days initially. i What causative organism might you culture from a tracheal aspirate? ii What laboratory tests allow monitoring of response to therapy? iii What are the complications of the treatment? iv What are the colt's prospects of becoming a performance animal? v Are any other treatments available?

152

153 A 20-hour-old foal (153a) presents with a 4-hour history of depression, colic, abdominal distension and diarrhoea, which contains large clots of blood (153b). i What is the most likely aetiology of the diarrhoea? ii What is your treatment plan?

153a

153b

139

152, 153: Answers 152 i Rhodococcus equi. The circumscribed radiodensities suggestive of pulmonary abscessation carry a high index of suspicion for R. equi infection. ii Total and differential leucocyte counts, plasma fibrinogen and platelet count. Return of the total and differential leucocyte counts and plasma fibrinogen levels to normal in combination with resolution of the radiographic abnormalities is usually a good indicator of successful treatment. Some authors have recognised a consistent thrombocytosis with this disease and have suggested that return of the platelet count to normal may also be a useful indicator of resolution. iii Treatment is expensive and labour intensive as multiple doses per day are required. Oral erythromycin can lead to severe enteritis and diarrhoea in some cases. Some foals may develop mild colic, loss of appetite and bruxism and foals outside in hot weather having occasionally been reported to develop spontaneous, idiosyncratic, possibly fatal pyrexic reactions (malignant hyperthermia) whilst on erythromycin therapy. In Scandinavia dams of foals being treated with erythromycin and rifampicin have developed severe and often fatal colitis. The aetiology is as yet unproven but is believed to be clostridial. iv Given that the foal responds to the treatment, moderate to good. v The organisms may be relatively susceptible to other antibiotics (e.g. trimethoprimsulphamethoxazole, gentamicin, tetracyclines and chloramphenicol) in vitro. However, very poor results have been reported with the use of these drugs in vivo. Protracted courses of trimethoprim-sulphamethoxazole have been used successfully in early cases prior to abscess formation. Anecdotal reports suggest that isoniazid is a cheap, relatively successful alternative. A spiramycin/rifampicin combination has been used successfully. 153 i The presentation is consistent with haemorrhagic necrotising enterocolitis. The most likely causes are clostridial toxins, such as those associated with C. difficile or C. perfringens (A, B, C). Although less likely, enteric Salmonella infection could also produce similar signs. ii (1) Fluid therapy, replacement IV fluids, possibly with sodium bicarbonate, are indicated. Often additional supplementation with potassium is necessary; (2) antibiotics: if Clostridium is suspected, then high doses of IV penicillin may be used (50,000 IU/kg every 6 hours) in addition to adequate Gram-negative coverage; (3) intestinal protectants; (4) anti-ulcer prophylaxis (histamine 2 receptor antagonists or proton pump blockers); (5) Clostridium antitoxin (C and D) has also been recommended in suspected cases of clostridial diarrhoea; (6) plasma may be of some benefit; (7) nutrition: removal of milk is recommended for severe diarrhoea, especially if blood is present. Calories are provided by oral glucose/electrolyte solutions and partial or total parenteral nutrition.

140

154, 155: Questions 154a

154b

154 A 13-year-old mare was examined for pregnancy 16 days after the last recorded mating. A single ovulation had been confirmed within 24 hours after mating. An apparently normal 28 mm vesicle with a 2 mm embryo was found in the left horn and a 12 mm vesicle in the right horn. One CL was seen in each ovary. The vesicle in the right horn was crushed manually and its complete disruption confirmed with ultrasound. Reexamination 4 days later is illustrated (154a). Two days later there was a similar picture and the results of an examination a further 2 days later are shown (154b, c). i What structures are visible in 154b, c? ii What comments can you make?

154c

155 A 24-hour-old Thoroughbred foal which has been heavily sedated (155). i What ophthalmic lesions are evident? ii Suggest how this foal sustained such damage? iii What other ophthalmic problems may also be present? iv How would you treat the ophthalmic lesions?

155

141

154, 155: Answers 154 i Originating from the periphery of the pregnancy at 3 o’clock, 7 o’clock and 9 o’clock are three embryos, each suspended by its own allantoic membrane and lifted clear of the conceptual wall by the developing allantoic cavity. No interface between any conceptus is visible. No interfaces could be seen from any angle, although heart beats were clearly visible in each embryo. This was obviously an extremely bizarre case from the first examination. ii (1) The 28 mm vesicle seen with an embryo on day 16 suggests that the mare must have been mated to an ovulation at least 4 days earlier than recorded. The 12 mm vesicle would have been undersize for the recorded ovulation; (2) the second examination, 20 days after the recorded ovulation, found embryos which by size would have been aged at 25 days, 23 days and 21 days; (3) from the stages of development seen at the examination 24 days after ovulation, the pregnancies would be aged as 29 days, 27 days and 25 days. The most bizarre finding was the absence of interfaces between the yolk sacs. It was confirmed at hysteroscopy and after flushing that all three embryos were within the same allantochorion, and by DNA ‘finger printing’ that they were identical, i.e. a case of monochorionic monozygotic triplets. 155 i Unilateral traumatic blepharitis, with severe lid excoriation and oedema. Excessive lacrimation is evident on the head ventral to the eye. ii This foal is suffering from NMS and convulsed at 16 hours old. Most of the convulsions took place with the foal in right lateral recumbency and this led to severe self-inflicted trauma to the right eye and bony prominences on the body and legs of the right side. iii This foal had a severe right-sided conjunctivitis, chemosis, mild corneal oedema, acute traumatic uveitis and blindness. The left eye was normal. Foals with NMS have also been recorded with retinal haemorrhages (see 101), various pupillary abnormalities, apparent blindness and scleral splashing, or subconjunctival haemorrhage (see 33). More recently papilloedema and changes in optic disc colouration have been detected. iv The ophthalmic lesions were treated alongside the intensive therapy and supportive care for the NMS. Cold compresses (6 times daily) were used to decrease the eyelid and conjunctival oedema with antibiotic/corticosteroid ophthalmic ointment smeared over the eyelid excoriation and placed in the conjunctival sac 4 times daily. The acute traumatic uveitis was treated with 4 times daily 1% atropine ointment placed in the conjunctival sac and a low dose of NSAIDs given systemically. Broadspectrum antibiotics were already being given as part of the supportive care.

142

156, 157: Questions 156 An owner informs you her pregnant (10 months gestation) mare has developed premature udder development and is lactating. i In what circumstances can this occur? ii What action would you take?

157a

157b

157 These two ovaries (157a–d) have a similar shape and texture when palpated. i Which different structures do they contain? ii Why is the similarity in shape and texture clinically relevant? iii How might you differentiate these structures in clinical practice?

157c

157d

143

156, 157: Answers 156 i Premature lactation is seen when partial separation of the chorion from the uterus occurs causing placental insufficiency, e.g. when one of twins dies in utero, or when separation results from an infective process (placentitis). Sometimes the cause is not apparent. ii Try to determine the cause by checking for any past history of twinning or placentitis, and for current pregnancy testing records or scans for signs of twinning. Check for evidence of purulent material in the posterial genital tract, using cytological and bacteriological examination. Use of transabdominal ultrasonography to assess the fetus and intrauterine environment would be helpful. Treat the mare with appropriate antibacterials to combat the risk of an ascending placentitis or treat an existing placentitis; use of the NSAID drug flunixin meglumine will help prevent prostaglandin release associated with placentitis and progesterone may help prevent premature delivery. Isoxsuprine may also be useful due to its tocolytic and vasodilatory properties. If regular ultrasonographic monitoring shows signs of fetal wellbeing deteriorating, parturition may have to be induced. Ensure that at birth the placenta is kept and inspected for evidence of twinning, placentitis or other abnormality. In the absence of twinning, take swabs routinely for microbiology, including antibiotic sensitivity. 157 i The ovary from the first mare (157a, b) contains a large, fluid-filled follicle, whilst that from the second mare (157c, d) contains a corpus haemorrhagicum (early CL). ii Since the corpus haemorrhagicum may feel similar to a preovulatory follicle when palpated per rectum, these structures may be confused. Mating or insemination may be attempted after ovulation. This may put the stallion at risk from injury and, in any case, may result in a low pregnancy rate and increased likelihood of embryonic mortality. iii The corpus haemorrhagicum may be readily identified if the mare has been examined daily. In this circumstance, softening, flattening or collapse of the follicle may be identified and the resultant corpus haemorrhagicum is often only 80% or less of the diameter of the pre-ovulatory follicle. In addition, the corpus haemorrhagicum may be painful and the mare may resent its palpation; she may twitch, look at her flank, or kick at her ventral abdomen. A more definite method of detecting the difference between these two structures is to use diagnostic ultrasonography; the preovulatory follicle will appear to be anechoic (black) and the corpus haemorrhagicum will appear to be hyperechoic (white), although the latter may have a central fluid-filled cavity.

144

158, 159: Questions 158a

158b

158 This parasite larva (158a) was cultured from the faeces of a weanling colt who developed acute, severe abdominal pain 48 hours after receiving a recommended dosage of ivermectin. The animal had received no other anthelmintic treatment since birth. The weanling was in severe pain, with a heart rate of 100/minute, respiratory rate of 40/minute, normal rectal temperature, gross abdominal distension, a high-pitched ping in the right paralumbar fossa on simultaneous auscultation and percussion, and brickred mucous membranes. Upon passage of a nasogastric tube, no reflux was obtained. i What is the parasite larva? ii An abdominocentesis was performed and a red, serosanguinous fluid was obtained (158b) with a nucleated cell count of 40 × 109/L (40,000 cells/+L), and a total protein of 45 g/L (4.5 g/dL). What does this tell you about the disease process in the abdominal cavity? iii What treatment would you recommend? iv What preventive strategy would you give the owner?

159 A 10-week-old foal had shown a persistent unilateral ocular discharge for some weeks which varied in nature from serous to mucopurulent (159a). i How would you investigate this? ii What treatment is possible?

159a

145

158, 159: Answers 158 i Cyathostomiasis (small strongyle infestation). These parasites live in the mucosa of the caecum and large intestine. Massive killing of a heavy parasite burden can cause a tremendous mucosal inflammation, disruption of GI motility, and subsequent severe colic. ii Normal peritoneal fluid is clear yellow, with a nucleated cell count 2.5 cm in diameter (214a, b) in two mutually perpendicular planes (short and long axis views). There is mild-to-moderate pulmonary artery hypoplasia and mild right ventricular outflow tract obstruction. There is mild-to-moderate left atrial and left ventricular volume overload, normal myocardial function and mild aortic regurgitation. The peak velocity of blood flow through the VSD obtained with continuous wave Doppler echocardiography (214c) is slightly >4 m/second in a leftto-right direction, but the colt was very agitated during the examination. iii This foal has a membranous VSD with mild pulmonary artery hypoplasia. iv The prognosis for this foal is guarded to fair for life and poor to grave for performance as the defect is of moderate size, there is mild-to-moderate pulmonary artery hypoplasia, mild right ventricular outflow tract obstruction, mild-to-moderate left atrial and left ventricular volume overload, mild aortic regurgitation and a peak velocity of shunt flow through the defect indicating a VSD which is probably haemodynamically significant. Membranous VSDs that measure 4 m/second through the VSD and normal systolic arterial blood pressure usually have a normal life-span with no performance problems.

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215, 216: Questions 215 During examination of an apparently healthy 3-day-old foal you detect a soft holosystolic cardiac murmur with a point of maximum intensity over the left heart base in the aortic valve region. What is the most likely cause for this cardiac murmur?

216a

216b

216 These ultrasound images were obtained from a 10-year-old Thoroughbred mare with a 2-day history of a long, although unassisted, foaling and retained fetal membranes (216a–c). The mare’s uterus was flushed but the mare reportedly became toxic and developed diarrhoea. The mare was febrile with progressive abdominal distension. GI sounds were decreased throughout the abdomen. The mare was haemoconcentrated, hyperproteinaemic, hyperfibrinogenaemic and azotaemic. i What are your differential diagnoses? ii What are the ultrasound findings? iii What is your diagnosis? iv What additional diagnostic tests are recommended?

216c

197

215, 216: Answers 215 The murmur auscultated in this foal is most likely an innocent flow murmur. It is not likely to be due to a PDA. Innocent flow murmurs are the most commonly auscultated flow disturbances in neonatal foals. In contrast, a murmur due to a functional PDA is rare, probably because the ductus arteriosus tends to close within the first 24 hours of life. A PDA murmur should be a machinery-type or least continuous through systole and into early diastole, and should have a point of maximum intensity dorsal and caudal to the aortic valve. 216 i They include a metritis, ruptured uterus, peritonitis or ruptured bladder. A uterine infection is likely with a retained placenta, but peritonitis must be considered, particularly in a mare with fever and progressive abdominal distension. A ruptured bladder must also be considered in the differential diagnosis for progressive abdominal distention following a lengthy parturition but is much less likely. ii Figure 216a, obtained with a 5.0 MHz sector scanner transducer, of the caudal ventral abdomen reveals a large quantity of free peritoneal fluid in the ventral abdomen with normal small (SI) and large (LI) intestine floating on top of the ventral fluid. The peritoneal fluid is anechoic with a small amount of hypoechoic material within. No fibrin strands or adhesions were visualised. Figure 216b, obtained with a 5.0 MHz linear transrectal transducer reveals a large defect (arrows) in the ventral wall of the bladder near the bladder apex and free fluid within the peritoneal cavity. Figure 216c reveals free air (arrows) adjacent to the dorsal bladder mucosa casting characteristic reverberation artifacts. iii Traumatic bladder rupture with uroperitoneum and a possible chemical peritonitis. The bladder rupture probably occurred at the time of the dystocia. iv A CBC, total protein content and fibrinogen should be repeated. Serum electrolytes should be obtained and a creatinine repeated. An abdominal paracentesis should be performed and the fluid submitted for electrolyte potassium and creatinine determination as well as cytological evaluation. Culture and sensitivity testing should be performed if indicated by cytological evaluation of the fluid.

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217: Questions 217a

217 A brood mare aborts a 10-months fetus suddenly and with no premonitory signs. A fresh fetus being expelled within the intact placenta. You perform an autopsy (217a). i What conditions might have an abortion history such as this? ii Describe the changes seen and give a differential diagnosis. iii What methods of laboratory investigation are currently used to confirm or refute a suspected diagnosis of EHV-l abortion?

199

217: Answers 217b

217 i An unheralded explosive abortion of a fetus within its membranes is highly suggestive of EHV-l abortion. Other conditions can also lead to a similar event and it is important to carry out laboratory investigations to reach a definitive diagnosis. Premature placental separation, with a ‘red bag’ presentation of an intact oedematous chorionic cervical pole, tearing of the chorion across the body and rapid expulsion of placenta and an asphyxiated fetus results in a very similar history. However, such fetuses are virus negative. ii Figure 217a shows pleural effusion in the thorax, lung oedema, a swollen thymus and enlarged liver and spleen with rounded edges. Tissues look fresh. These features are very suggestive, but not pathognomonic, of EHV-1 abortion and measures should be taken to investigate this. Other conditions involving vascular compromise or fetal septicaemia might also produce some of these changes, so it is prudent to check the integrity of the umbilical and allantochorionic circulation, heart and great vessels, and culture fetal heart blood and lungs. iii Apart from attempts to isolate virus in tissue culture, from homogenates of fetal tissues, a number of histopathological techniques are in routine use. The presence of intranuclear viral inclusion bodies (pink), particularly when associated with focal tissue necrosis is highly supportive of a positive diagnosis of EHV-l (see 192). Typical lesions can usually be found in H&E sections of liver (in 96% of positives), lung (67%) or adrenal (82%) as well as in other tissues. Rapid methods of screening, e.g.using frozen H&E sections, are useful for providing preliminary data: liver and lung is the best combination of tissues to screen, as adrenal changes can be more difficult to assess. Because virus isolation may take 8 days to complete, immunostaining methods have been developed to increase the specificity of histological diagnosis. These methods have advantages and disadvantages: they are time consuming, reagents are expensive and they require experienced personnel to prepare and to read the slides. They therefore tend to be used only for problematic cases, or for research. The fluorescent antibody technique uses frozen sections, and requires darkroom fluorescence microscopy. It can be performed within half a day but because it fades, slides need to be read the same day and there is no permanent record other than a photographic one. Use of IP sections take a day, but as thinner, paraffin sections are used they are preferable and provide a (semi) permanent record. IP is a very sensitive way of detecting the presence of EHV-l antigen, including at loci where, in the absence of inclusion bodies or apparent loss of cell integrity, the presence of virus would not be apparent on an H&E section (217b shows IP staining of EHV-1 in a placental wall).

200

Index All references are to question and answer numbers Aanes technique 62 abdominal abscess 56 abdominal distension in foal 29, 48, 80, 86, 153, 204, 210 in mare 198, 216 abdominal intussusception 107 abdominal pain (in foal) 18 abdominal paracentesis 56, 216 abdominal radiography 80 abdominal ultrasound 48, 80, 194 in pregnant mare 151 in premature foal 107 umbilical structures in 100 abdominocentesis 48, 158, 197 abortion 126 of autolysed fetus 32 contagious 10 of fetus with absent foot 39 investigation procedures for 25 and Klebsiella 133 in Thoroughbreds 32 see also EHV-1 ‘abortion storm’ 192 abscess 41 abdominal 56 pulmonary 56 umbilical 54, 123 urachal 123 acidaemia 70, 81 ACTH 68, 138 adoption 51 adrenocortical nodules 128 agglutination test jaundice foal 132 latex 210 slide 15 aggression 162 AI 60, 63, 78 procedures 3 in controlling venereal disease 7 see also insemination, timing of; semen allantochorion 179, 193 allantochorionic folding 194 allantochorionic pouches 144 alveolar hypoventilation 70 amino acids supplementation 11

amniotic band, ligation by 39 anaemia 33 anaesthetic procedures for caesarian section 195 for removal of dead foal 205 for young foal 71 angulation, limb 143 anoestrus 64, 69, 104 arthritis, septic 89, 147, 202, 207 arthrocentesis 207 arthrogryposis 166, 180 artificial insemination, see AI artificial lighting regime 165 artificial vagina 43 bull model 37 Colorado model 37, 184 Hannover model 37, 184 methods of obtaining ejaculate 50 preparing novice stallion for 37 ascarid worm impaction 173 Asidia spp., placentitis 171 Aspergillus fumigatus placentitis 171 Aspergillus spp. 99 asphyxia birth, 176, 178 prepartum 187 atheroma 206 atresia coli 29, 93, 107 autolysed fetus 32 azotaemia 216 bacterial cultures 26, 134, 137, 139 barren mares 13, 120 bed sore 147 bicarbonate therapy 81 bladder prolapse 140 bladder, ruptured 29, 93, 204, 216 surgical procedures 86 blastocyst, abnormal implantation 94 blepharitis 155 blood culture 38, 70, 80, 176, 187, 207 blood gas analysis, arterial 80, 81, 170, 187 blood urea nitrogen 35 body pregnancy 126, 133, 167 bog spavin 202 Bolz operation 112 botulism 70, 73 bowel loops, prolapsed 140 brain defects, congenital 70

201

breeding, assessment for 60, 189 breeding phantom 43, 50 bull’s eye signs, foal ultrasound 107 caesarean section 180 anaesthetic protocol for 195 salvage 199 capsule typing 134 carcinoma 41 squamous cell 142, 149 cardiac anomaly, congenital 170, 187 cardiac murmur 170, 187, 214, 215 carpal bone fracture 21 carpal swellings 4 carpal valgus neonatal bilateral 58 carpal varus, bilateral 114 carpus congenital flexural deformity of 166 flexural deformity of 79 caslick vulvoplasty 90 ‘caslicked’ mare 19, 60 castration 9 and ornental prolapse 40 and small intestinal prolapse 49 unilateral 208 cataract 183 nuclear 164 cauterisation 46, 48, 92 CBC 35, 38, 48, 68, 70, 80, 89, 103, 107, 139, 152, 170, 176–8, 187, 191, 197, 202, 207 celiotomy, ventral midline 107 CEMO 26, 36 control of 137 see alsoTaylorella eguigenitalis cervical star 25, 94, 171, 179, 194 cervical stenosis 120 cervicitis 90 cervix condition of 69 incompetent 13 methods of assessment of 64 palpation of 64, 69 ultrasound 57 Cheyne–Stokes respiration 70 chorion pallor of 94 villus surface of 133 chorionic distortion 94 chorioretinitis 101 cleft palate 121

202

club foot 95 CL early, see corpus haemorrhagicum estimation of age of 77 premature regression of 34, 113 ultrasonic detection of 12, 20, 203 clitoral sinusectomy 36 clitoris, anatomy of 36 clostridial infection 80, 153 Clostridium botulinum 73 Clostridium spp. 210 colic 80, 85, 93, 204 colon prolapse, small 140 colonic distension 197 colostrum 115, 211 bovine 51 comet tail artifacts 187 conceptus development 182 conjunctivitis 159 Coomb’s test 132 coprophagy 31 cornea, foreign body on 131 corneal ulceration 5, 131 coronary band, purple 210 coronavirus 80 corpus haemorrhagicum 27, 77, 157, 203 cortisol 68, 138 Cowdry type A inclusion bodies 192 creatinine levels 35, 48, 216 Crocott silver stain 66 cryosurgery 149 cryptorchidism 8, 172 cryptosporidium 80 CSF tap 103 Cushing’s syndrome 138 cyanosis 170 cyathostomiasis 158 larval 191 cyst dentigerous 1 endometrial 20, 94, 127 epidermal inclusion 106 fossa 196 inclusion 196 ovarian 128 periovarian 91 retention 196 uterine 92, 135 extra-luminal 189 cystadenoma 41 cystic ovary 61 cystitis 76

defaecation straining 18, 93 deficiencies, trace elements 11 dentigerous cyst 1 Descemet’s membrane, herniation of 131 dexamethasone suppression test 138 diabetes 138 diaphragmatic hernia, congenital 82 diarrhoea 31, 153, 191 rotavirus 210 viral 80 yellow 210 DIC 33 Dictyocaulus amfieldi 88 digital extensor tendon, rupture of 4 dioestrus 27, 46, 64, 69, 105, 116, 128 distal punctum, surgical creation of 159 DNA viruses 181 DOD 124 donkey 197 dopamine agonists 138 DSO 78 dummy mare 43, 50 dysgerminoma 41 dysmaturity 68 dystocia 180 birth after prolonged 176–8 ear, petechial haemorrhage 38 eCG 15, 141 echocardiogram 170, 187, 214 EHV 181 EHV-l 10, 24, 25, 32, 187, 192 histopathological diagnosis of 217 see also abortion EHV-2 181 EHV-3 7, 130 EHV-4 24 ejaculate selection of for insemination 74 ejaculation, evidence of 43 elbow joint infection 207 electrocautery 149 electrolytes loss of 81, 93 serum 48, 216 ELISA test 56, 69, 80, 210 embryonic vesicles needle puncture of 84 small-for-age 84, 113 twin 53, 84, 160 ultrasound and 20, 65, 160 embryos, triple 154

embryotomy 205 endocarditis, bacterial 56 endocrine status 41, 64 endometrial biopsy 46 endometrial cups 15, 141, 144 endometrial cyst 20, 94, 127 see also uterine cyst endometrial epithelial cells 190 endometrial folds 98 endometrial oedema 105, 127 endometritis 2, 10, 13, 90, 105, 168 acute 34, 111, 190 biopsy 14 Klebsiella 133 post-mating 77 severe 116 endometrium 116, 144 endoscopy 46, 116 enteritis 93 Enterobacter aerogenes 134 enterocentesis 197 enterocolitis 29 haemorrhagic necrotising 153 entropion 5 eosinophils 88 epidermal inclusion cyst 206 epidural block 109 episioplasty 90 equine coital exanthema 7, 130 Equitainer system 150 erythromycin 152 Escherichia coli 80, 111, 171 EVA 10, 24 extenders, semen 106 fertility post-surgery 63 uterine cysts and 92 fetal fluid loss 151 fetal maceration 209 fetotomy 22, 67 fetus aborted 39 autolysed 32 mummified 200, 213 see also triplets, twins fibrinogen 35, 38, 48, 68, 70, 80, 89, 197, 202, 207 fistula, rectovaginal flexor deformity acquired 95, 102 carpal valgus 79

203

flexor deformity cont. congenital 166, 211 flexor tendon hyperextension of 30 severed 96 fluid therapy 81, 107, 153 fluorescent antibody technique 217 foal dead at parturition 22 procedures for removal 205 foal heat diarrhoea 31 foaling, induced 68, 129, 146, 199 follicles, ovarian 77 enlarged 55 fluid-filled 157 haemorrhagic 41, 175 luteinised 41, 47, 175 pre-ovulatory 157, 175 ready for mating 72 in regression 91 foot-nape posture 163 forage analysis 99 foreign body, corneal 131 fractures 6, 21 gastric ulceration 71 gelding, stallion-like behaviour in 8 genital discharge 168 genital tumour 149 GI obstruction 93 glans penis, granulating masses on 110, 142 gluteal nerve, paralysis of 125 Goetze technique 62 GTCT 41, 61, 162 guttural pouch washings 186 haemangioma 57 haematoma 198 ovarian 41 penile 28 haemolysis 48 haemolytic streptococci 171 haemorrhage internal 62 umbilical 48 vitreous and vitreal 183 haemorrhagic necrotising enterocolitis 153 H&E sections, liver 217 harvest mite 44 hay 99 hCG 185 heart murmur 214, 215

204

hepatic disease 48 hernia congenital diaphragmatic 82 Descemet’s membrane 131 inguinal 122 strangulated 93 umbilical 54, 123 ventral 198, 199 herniorrhaphy 122 hGC stimulation test 8 HIE 70, 103, 178 hippomanes 75 hirsutism 138 hormone assays 45, 61 horn, see uterine horn hyaloid artery 183 hyaloid apparatus, persistent 183 Hydatid of Morgagni 91 hydrops, placental 198 hymen, imperforate 57 hyperandrenocorticism 138 hyperbilirubinaemia, neonatal 132 hyperfibrinogenaemia 191, 216 hyperhydrosis 138 hyperproteinaemia 191, 216 hyphaema 33 hypoalbuminaemia 191 hypoglycaemia 73 hypoventilation, alveolar 70 hypoxia, intra-uterine 151 hypoxic bowel syndrome 107 icterus 48 IgG 35, 38, 51, 80, 115, 187, 202, 212 immunodeficiency syndrome, see SCID immunoglobin status 176, 197 induction, parturition 68, 129, 146, 199 influenza 24 infundibulum 83, 104 inguinal hernia 122 innocent flow murmur 215 insemination, timing of 91, 185 see also AI interphalangeal joint, flexural deformity of 95, 102, 211 intestine, small intussusception 29 obstruction 204 prolapse 49, 140 ultrasound images of 203 intrafollicular haemorrhage 47 intra-uterine hypoxia, chronic 151

in utero moulding 143 in utero stress 115, 129 IP sections, for EHV-1 antigens 217 iron toxicity 132 ivermectin 88, 158, 173, 191 Jaundice Foal Agglutination Test 132 jejunal intussusception 107 jump mare 50 keratoconjunctivitis, viral 181 Klebsiella endometritis 133 Klebsiella pneumoniae 36, 38, 134 knuckling over, foal 4, 166, 211 lactation, premature 115, 151, 156, 171 lens, dislocated (luxated) 164 leptospirosis 10, 132 leucocytes, see PMNs leucocytosis 115, 191 libido, lack of 108 liver section 192 luminal fluid, free 127, 105 lung scan 187 lungworm 88 luteal regression 113 luteinised follicle 175 lymphopenia 212 lysine 11 maxillary–mandibular malocclusion 121 meconium aspiration of 129, 146 impaction 197, 204 pellets removal 93 retained (RM) 93 melanoma, melanosarcoma 148 meningitis 178 bacterial 103 mentation, abnormal 178 metacarpophalangeal joint deformity 211 microcotyledons 75 microscope, phase-contrast light 97 milk replacers 81, 177 mineral deficiency 11 mount mare 43, 50 mucous membranes 197 blanched 62 cyanotic 170 yellow 48, 192 mummified fetus/foal 200, 213

murmur cardiac 170, 214, 215 innocent flow 215 myocarditis 187 neonatal hyperbilirubinaemia 132 neonatal renal disease 35 neonatal respiratory distress syndrome 187 neonatal septicaemia 48, 176, 194, 210 neoplastic lesions 41 NI 132 NMS 33, 70, 103, 155, 176, 178, 187 see also HIE NSAIDs 81, 122, 139, 145, 155, 156, 166, 195, 208 nutrition 11, 81, 103, 124, 153 nutritional myodystrophy 73 ocular discharge 159 oestrogen 41, 64 oestrous behaviour 72 irregular 41, 47, 55, 61 and ovary appearance 69 and ovulation prediction 118 prolonged in vernal transition 165 oestrous cycle artificial lighting to accelerate 165 cervical assessment of uterus changes during 104 oestrus 64, 69, 104 ultrasound evidence of 2, 27 omental prolapse 40 orchitis, acute septic 208 ossification, inadequate 16, 115 osteochondreal fragment 202 osteochondritis dissecans 119 osteomyelitis 38 ovarian cyst 61, 128, 134 ovarian haematoma 41 ovarian tumour 162 ovariectomy 41 ovary enlarged 41, 47 examination of 65, 69 with pre-ovulatory follicle 157 proper ligament of 104 removal of 61 ultrasound scan of during oestrus 91 visceral peritoneum covering 83 see also corpus haemorrhagicum; CL; follicles, ovarian

205

ovulation, ultrasound evidence of 2, 12, 27, 34 ovulation fossa 83 oxytetracycline 166, 211 oxytocin 145 papules, crusty 44 para-bursal cysts 128 paralysis flaccid 73 gluteal nerve 125 paraphimosis 28, 59 parturition characteristic stages of 17 removal of dead foal at 22 parvovirus 80 passive transfer, failure of 80, 136, 170, 177 pasture management 11 PDA murmur 215 pelvic brim, conformation of 13 penile haematoma 28 penis diseased 7, 110, 142 paralysis/prolapse of 112 perineal architecture 14 preparation of, for semen collection 188 perineal body transection 90 perineal laceration 19, 60, 62 periovarian cyst 91 peritoneal fluid 56, 158, 216 peritonitis 48, 56, 216 phantom, breeding 43, 50 physeal dysplasia 124 physitis, septic 207 pinkeye 24 placenta examination of 75, 193 expulsion, normal timing of 145 thickened areas of 35 placental bleeding 76 placental dehiscence 52 placental dysfunction 35 placental folding 194 placental hydrops 198 placental insufficiency 133, 151, 213 placental prolapse 140 placental retention 52, 145, 180, 216 placental separation, premature 52, 76, 194, 217 placentitis 76, 115, 156, 213

206

placentitis cont. Aspergillus fumigatus 171 infective 10, 133 plasma transfusion 51, 81, 177, 187 pleural effusion 187, 192 PMNs 34, 111, 190 Pneumabort K 192 Pneumocystis carinii 66 pneumonia 56, 187 pneumovagina 13, 14, 90 Pollack’s trichrome 111, 190 potassium 153, 216 PPM 183 pregnancy ‘body’ 126, 133, 167 ‘upside down’ 167 see also twins pregnancy diagnosis 12, 84 ultrasound 12, 20, 27, 32, 42, 53, 65, 84, 154, 167, 174 premature foal 115, 171 abdominal ultrasound for 107 pneumonia in 187 prepartum asphyxia 187 prepubic tendon rupture 198, 199 preputial bleeding 142 preputial fold granuloma 59 pressure sores 21 progesterone 41, 61, 64, 69, 113, 141 prolapse omental 40 in post-partum mare 140 rectal 148 small intestinal 49 prostaglandin 60, 84, 120 protein loss 191 Pseudomonas aeruginosa 36, 134 pulmonary abscess 56 pulmonary oedema 187 pulmonic stenosis 214 pyometra 120 radiation therapy 149 radiography 80, 202, 207 RBCs destruction/replacement 132 rectal prolapse 148 rectovaginal fistula 163 ‘red bag’ presentation 217 reefing 59 renal disease, neonatal 35 respiration, Cheyne–Stokes 70 respiratory tract infection 56

retinal haemorrhage 33, 101, 155 Rhodococcus equi 56, 152 rotavirus 80, 210 rupture bladder 86, 204 surgery procedures 86 digital extensor tendon 4 prepubic tendon 198, 199 urachus 29 urethral 29, 93 uterus 216 Salmonella spp. 210 salmonella/salmonellosis 56, 80, 153 salvage caesarean section 199 sarcoid 149 SCID 212 scleral haemorrhage 33 seedy toe 102 seizures, control of 103 selenium deficiency 73 semen chilled 150 insemination of 182, 185 collection of 43, 188 see also artificial vagina frozen 161, 185 motility assessment 97 storage extenders for 106 sepsis, neonatal 48 sepsis score 38, 70 septicaemia 38, 80, 132, 217 neonatal 176, 210 septic arthritis 89, 147, 207 septic orchitis 208 septic physitis 207 serum biochemical profile 35, 80 serum electrolytes 48 sesamoid bone fracture 6 shoulder flexion posture 22 silage 99 smegma 36 smegmolith 110 sperm cell slides 87 estimation of production of 78 morphology assessment of 87 motility of 74 spermatic cord torsion 23 spinal block 109 spinal cord lesion 73 splints 30, 166, 211

squamous cell carcinoma 142, 149 stallion-like behaviour 8 strangles 186 stranguria 110 streptococci, haemolytic 159, 171, 190 Streptococcus equi 186 Streptococcus spp. 208 Streptococcus zooepidemicus 120 strongyles 158 subconjunctival haemorrhage 33, 155 supplements, nutritional 11 supra-orbital fat 138 surgery procedures ruptured bladder 86 tumour excision 149 uterine torsion 85 synovial fluid analysis 89, 202 synovitis, septic 38, 139 systolic murmur 214 tachycardia 132, 152, 170, 173 tapetal fundus lesions 101 tarsal bone ossification 16 tarsal valgus 89, 202 tarsometatarsal joint 143 Taylorella eguigenitalis 26, 36, 137 see also CEMO tendons, digital extensor 4 tenesmus 57 tenosynovitis 147 teratoma 41 testicle, cystic degeneration of 45 testicular rotation 23 testis condition, assessment methods 45 testosterone 41, 172 tetanus 136 tetralogy of Fallot 170 thoracic radiography 146, 152, 187 thrombocytopenia 33 thrombocytosis 152 tissue perfusion, poor 81 TNM 78 trace elements 11 transcornual migration 174 transtracheal aspirate 56, 187 triplet embryos, monochorionic monozygotic 154 Trombicula autumnalis 44 tumour ovarian 162 vaginal wall 57

207

twins 76, 135, 156, 200 as cause of abortion 10, 32, 133 mummified 213 ultrasound diagnosis of 53, 65, 84, 160 see also embryonic vesicles udder development, premature 151, 156, 213 ulcer corneal 5, 131 gastric 71 ulcer medication 81 ulnar carpal bone fracture 21 ultrasound abdominal 48, 80, 100, 107, 123, 151, 156, 194 cervix 57 embryonic vesicle identification 65 GTCT 41 hyperechoic areas 209 oestrus evidence 2 ovaries/uterus 27, 42, 77, 91 pregnancy diagnosis 12, 20, 32, 84, 154, 167, 174 twin 53, 84, 160 small intestine 203 specular reflections 42 testicles 45 transrectal 194 umbilical 100, 207 uterine body 105, 120 uterine horn 42, 46, 98, 104, 120 vagina 57 umbilical abscess 54, 123 umbilical cord, long twisted 32 umbilical hernia 54, 123 umbilical infection 169 umbilical remnants, internal 207 umbilical stalk ligature 48 umbilical structures 100 upside down pregnancy 167 urachal abscess 123 urachal diverticulum 169 urachus 29 ureter 29, 93 urethral fossa smegmolith 110 urethral obstruction/rupture 93 urethritis 76 urinary discharge 168 urinary tract 169 urination posture 18

208

urine dark 132 neonatal first passage of 117 urine pooling 13 vaginal 168 urolithiasis 76 uroperitoneum 80, 204, 216 urovagina 90 uterine anatomy 104, 105 uterine cyst 92, 135, 189 see also endometrial cyst uterine endoscopy 116 uterine fluid 42, 105, 127 uterine horn 75 obstruction of 46 pregnant/non-pregnant comparison 193 and ultrasonography 42, 46, 98, 104, 135, 189 uterine rupture 140, 216 uterine torsion 85 uterine tubal membrane 104 uteroplacental discontinuity 194 Utrecht fetatome 67 uveitis 155, 164 vagina, artificial see artificial vagina vaginal process 172 vaginal venous varicosities 76 vaginal wall tumour 57 vaginitis 90 vasculitis 33 ventilation, artificial 70, 71 ventral hernia 198, 199 ventricular septal defect 214 vernal transition 61, 69, 128, 165 vesicles, see embryonic vesicles viral diarrhoea 80 viral diseases 24, 181 vitamin E 73 vitreal/vitreous haemorrhage 183 vulval conformation 90, 209 vulval discharge 76, 168 vulval eversion 118 white muscle disease 73 ‘winking’ 118 wrynose 121 yolk sacs lack of interface between 154 vestigial 75