Clinical

Equine castration: review of

Australian anatomy, approaches, techniques VE T E R I N A R Y and complications in normal, OU R N A L J cryptorchid and monorchid horses

CLINICAL SECTION D SEARLE, AJ DART, CM DART and DR HODGSON University Veterinary Centre, Department of Veterinary Clinical Sciences, The Uni- EDITOR versity of Sydney,Werombi Road, Camden, New South Wales 2570 DAVID WATSON

ADVISORY COMMITTEE Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understand- AVIAN ing of the embryological development and surgical anatomy is essential to differen- LUCIO FILIPPICH tiate abnormal from normal structures and to minimise complications. Castration of EQUINE the normal horse can be performed using sedation and regional anaesthesia while DAVID HODGSON the horse is standing, or under general anaesthesia when it is recumbent.Castra- OPHTHALMOLOGY tion of cryptorchid horses is best performed under general anaesthesia at a surgi- JEFF SMITH cal facility. Techniques for castration include open, closed and half-closed tech- PRODUCTION ANIMALS niques. Failure of left and right testicles to descend occurs with nearly equal fre- JAKOB MALMO quency, however, the left testicle is found in the abdomen in 75% of cryptorchid SMALL ANIMALS horses compared to 42% of right testicles. Bilateral cryptorchid and monorchid JILL MADDISON horses are uncommon. Surgical approaches described for the castration of cryp- SURGERY torchid horses include an inguinal approach with or without retrieval of the scrotal GEOFF ROBINS ligament, a parainguinal approach, or less commonly a suprapubic paramedian or ZOO/EXOTIC ANIMALS flank approach. Laparoscopic castration of cryptorchid horses has recently been LARRY VOGELNEST described but the technique has limited application in practice at this time. A defini- tive diagnosis of monorchidism can only be made after surgical exploration of the EDITORIAL ADMINISTRATION AND abdomen, removal of the normal testis and hormonal testing. Hormonal assays DESKTOP PUBLISHING ANNA GALLO reported to be useful include analysis of basal plasma or serum testosterone or oestrone sulphate concentrations, testosterone concentrations following hCG stim- ulation, and faecal oestrone sulphate concentrations. Reported complications of CONTRIBUTIONS INVITED castration include postoperative swelling, excessive haemorrhage, eventration, Practising veterinarians and others are invited f u n i c u l i t i s, peri t o n i t i s, hy d r o c e l e, penile damage and continued stallion-like to contribute clinical articles to the Australian behaviour. Veterinary Journal. We will consider material Aust Vet J 1999;77:428-434 in a variety of formats, including clinically Key words: Horse, equine, castration, cryptorchid, monorchid. orientated reviews, reports of case series, individual case studies, diagnostic exercises, and letters containing comments or queries. astration is one of the most ment and anatomical features of the Practitioners are also invited to contribute to common surgical pro c e d u re s male equine re p ro d u c t i ve tract, the 1,2 approaches to castration of the normal, the case notes feature, where accepted arti- Cperformed in equine practice. cles are not peer reviewed but are edited for Although the pro c e d u re is considere d cryptorchid, and monorchid horse, and publication. Contributors should consult routine, surgical complications consti- the diagnosis and management of instructions to authors and recent issues of tute the most common cause of surgical complications. the journal for guidelines as to formatting. malpractice claims against equine prac- 3 Over referencing should be avoided: authors titioners in North America. A complete Embryonic development and should preferably quote only those articles understanding of male re p ro d u c t i ve surgical anatomy of the equine they feel are most likely to be of interest and anatomy and physiology and good testis benefit to readers. surgical technique will reduce the rate The embryonic gonad differe n t i a t e s 1 of surgical complications. Pre s u r g i c a l into a testis at approximately 5 ⁄2 we e k s Send all contributions to: e valuation and surgical approach to of gestation, at which time it lies on the Editor, AVJ Clinical Section cryptorchid and monorchid horses are a ventral aspect of the mesonephric AVA House, 272 Brunswick Road, m o re complex diagnostic and surgical k i d n e y.4,5 A re t roperitoneal cord of Brunswick, Vic. 3056, challenge. This article provides practi- mesenchyme coursing across the phone: (03) 9387 2982 tioners with a re v i ew of re l e vant infor- abdominal cavity from the caudal pole fax: (03) 9388 0112 mation on the embryological deve l o p- of the testis to an extraperitoneal posi- email: [email protected]. tion at the site of the future scro t u m 5 IM Intramuscularly forms the gubernaculum. The guber- IV Intravenously naculum is divided into two parts by the mesonephric duct which ultimately

428 Aust Vet J Vol 77, No 7, July 1999 Clinical d i f f e rentiates into the epididymis.4 At p e r i t o n e u m day 45 a peritoneal outpouching at the k n own as the site of the future internal inguinal ring tunica va g i- i n vades the extraperitoneal segment of n a l i s .2 , 5 T h e the gubernaculum forming the va g i n a l tunica va g i n a l i s p ro c e s s .5 Ul t i m a t e l y, when it is consists of completely differentiated, the gubernac- visceral and pari- ulum can be divided into the thre e etal tunics. T h e different segments identified in the adult visceral tunic is horse: the proper ligament of the testis tightly adhere d lies between the caudal pole of the to the testicle, m a t u re testis and the tail of the ducts and vessels, epididymis, the ligament of the tail of and the parietal the epididymis lies between the tail of tunic is contin- the epididymis and the parietal tunic of uous with the the vaginal process, and the scrotal liga- parietal perito- ment lies between the parietal tunic of neum (Figure 1).5 the vaginal process and the scro t u m The cre m a s t e r (Figure 1).5 muscle is a At approximately 6 weeks gestation, c a u d o l a t e r a l the interstitial cells of the testis begin to extension of the m u l t i p l y. By 5 months the embryo n i c internal abdom- testicle approaches the size of that of a inal oblique m a t u re stallion and lies in contact with muscle and is the kidney and the internal inguinal continuous with r i n g .4 , 5 Be t ween 7 and 10 months of the parietal laye r gestation the testicle atrophies to of the tunica a p p roximately one tenth of its former v a g i n a l i s s i ze as the gubernaculum short e n s .4 , 5 i n s e rting at the The epididymis and the ligament of the caudal pole of the tail of the epididymis expand to dilate testicle (Fi g u re Figure 1.The testicular structures seen during castration of the the vaginal ring and inguinal canal.5 2 ) .5 The parietal mature male horse using an open castration tech n i q u e. T h e Ultimately, at 9 and 10 months of gesta- tunic is inti- testicle (t) is tightly enclosed in the tunica albuginea.The head of the epididymis (a) continues as the body (b) and the tail (c) the tion dilation of the inguinal ring, mately adhere n t latter continues as the vas deferens (d).The tail of the epididymis to the scrotal skin contraction of the gubernaculum and is attached to the caudal pole of the testis by the proper ligament t h rough the i n c rease in intra-abdominal pre s s u re of the testis (e).This continues as the ligament of the tail of the combine to force the small, flaccid s c rotal fascia and epididymis (f) between the tail of the epididymis and the parietal 5 testicle into the inguinal ring. T h e tunica dart o s tunic (pt).The visceral tunic cov e rs the visceral surface of the 2 , 5 volume of extra-abdominal gubernac- m u s c l e . T h e t e s t i cl e, e p i d i dy m i s , spermatic vessels (sv), and vas defe r e n s . ulum pre vents the testicle fro m tunica dart o s The parietal tunic and cremaster muscle (cm) have been incised descending completely into the scrotum, sends a sagittal and are partially retracted. so at birth the testicles usually lie within septum into the the inguinal rings.4,5 The mass of guber- s c rotal sac naculum is quite large at birth and may dividing it into left and right pouches.5 external examination of the reproductive 5 be mistaken for a testicle.5 During the The spermatic cord courses fro m t r a c t . Sedation may be re q u i red to first few weeks of life vaginal rings abdomen to scrotum through the palpate the scrotum and the inguinal contract to approximately 1 cm in diam- inguinal canal which is bounded by deep canals for the presence of two testicles eter and gubernacular tissues reduce in and superficial inguinal rings. The deep and absence of an inguinal hernia. s i ze, allowing the testicle to assume a inguinal ring is a dilatable opening Tetanus prophylaxis should be curre n t . scrotal position.4,5 b e t ween internal abdominal oblique Some practitioners choose to give The testicular tissue is encased in the muscle, rectus abdominus muscle, p rocaine penicillin (20 mg/kg IM) tunica albuginea.2,5 In the horse the left prepubic tendon and inguinal ligament. p rophylactically prior to surgery. T h e testicle is usually larger than the right The superficial inguinal ring is formed efficacy of this in reducing postoperative and is suspended more ventrally and by a small opening in the external complications in castration of normal situated more caudally.5 The head of the abdominal oblique muscle. horses is questionable. The use of epididymis is found cranially continuing a n t i m i c robials for horses undergoing as the body and tail to become the Preoperative considerations c ry p t o rchid or monorchid castration should be considered on a case-by - c a s e ductus deferens caudally.5 The testicles Be f o re castration all horses should basis but cannot be a substitute for lie within an outpocket of abdominal undergo physical examination including aseptic technique. Preoperative adminis-

Aust Vet J Vol 77, No 7, July 1999 429 Clinical

Various re g i o n a l tration. Thiobarbiturates (thiopentone anaesthetic tech- sodium 4 to 8 mg/kg IV to effect) niques have been a d m i n i s t e red following sedation with d e s cribed for castra- xylazine hyd rochloride (0.3 to 0.5 tion of the standing mg/kg IV) or acepromazine (0.03 to ho r s e .2,5,6 L o c a l 0.05 mg/kg IV), or given with or after a naes-thetic can be muscle relaxants such as guaifenesin injected into the (100 mg/kg IV to effect) have been spermatic cord , recommended for short anaesthetic t e s t i c u l a r p ro c e d u re s .2 While these combinations p a renchyma, or p rovide excellent muscle relaxation and both. The testicular analgesia, anaesthetic re c ove ry may be n e rves may be c o n s i d e red less than satisfactory if anaesthetised by repeated administration of the barbitu- d i rectly injecting rate is required.2,5 15 to 30 mL of Xylazine hyd rochloride (1.1 mg/kg local anaesthetic IV) followed by ketamine hydrochloride into the sp e r m a t i c (2.2 mg/kg IV) combined with c o rd using a 21- d i a zepam (0.05 to 0.1mg/kg IV) is an Figure 2.The testicular structures seen during castration of the gauge 1.5 inch e f f e c t i ve combination.2 , 5 Di a ze p a m adult male horse using a closed tech n i q u e.The testicle (t) and needle. This can be p rovides muscle relaxation and appears the tail of the epididymis (c) are outlined within the parietal tunic achieved by placing to improve the quality of anaesthetic (pt).The cremaster muscle (cm) can be seen fanning out to insert gentle traction on induction and recovery. The addition of towards the caudal pole of the testis (cp).The scrotal fascia (sf) the testicle allowing butorphanol tartrate (0.02 to 0.03 remaining after the testicle and cord have been stripped can still access to the sper- mg/kg IV) will provide additional anal- be seen. matic cord or by gesia and may improve anaesthetic depositing the local re c ove ry. This combination generally anaesthetic at the a l l ows at least 12 to 15 min of surgical tration of a nonsteroidal anti-inflamma- l e vel of the superficial inguinal ring.2 time. Additional doses of xylazine (0.25 t o ry drug (phenylbutazone 2.2 to 4.4 Infiltration of the spermatic cord may mg/kg IV) and ketamine (0.5 mg/kg IV) mg/kg or flunixin meglumine 1 mg/kg), occasionally cause a haematoma which can be used safely to extend surgical and postoperative administration as can interf e re with application of the anaesthesia. required, may help control postoperative e m a s c u l a t o r.5 When injecting into the pain and swelling. testicular parenchyma, the testis is Cryptorchid castration Castration can be performed in the tensed in the fundus of the scrotum and Unless the position of the non- standing sedated horse using re g i o n a l 15 to 25 mL of local anaesthetic is descended testicle can be accurately anaesthesia or with the horse under injected into the parenchyma of each determined and is easily accessible, this general anaesthesia. The choice is largely testis using a 18-gauge 1.5 inch needle. s u r g e ry is best performed at a surgical 3,5 based on the surgeon’s pre f e rence and Gi ven sufficient time the local anaes- centre under gaseous anaesthesia. experience. Docile colts whose genitals thetic is proposed to diffuse from the can be palpated readily without sedation pampiniform plexus to anaesthetise the Surgical techniques for castration a re usually the safest candidates for c o rd .2 When combining both tech- of normal horses standing castration.5 niques, infiltration of the testicle first Surgical re m oval of the descended can facilitate access to the cord in testis can be performed using an open Sedation and anaesthesia for cas - anxious horses. In our hands this combi- or closed technique. T h e re is also a va r i- tration nation provides reliable anaesthesia for ation on the closed technique re f e r re d Standing castration most horses. Using either technique, 5 to as half-closed or semi-closed castra- A combination of physical and chem- to 10 mL of local anaesthetic should be t i o n .2,5 T h e re are several modifications ical restraint and regional anaesthesia is deposited under the scrotal skin either of each technique but, re g a rdless of generally re c o m m e n d e d .2 Drugs used side of the median raphe along the whether the horse is sedated and c o m m o n l y, alone or in combination, proposed incision line.2 standing or recumbent and anaes- include acepromazine, xylazine thetised, the surgical principles for h yd rochloride, romifidine, detomidine Recumbent castration castration remain the same.. 2 , 5 Tr a d i- hydrochloride and butorphanol tartrate. We prefer to use general anaesthesia t i o n a l l y, castration techniques allow for A combination of detomidine because surgical exposure is improve d second intention healing of scro t a l h yd rochloride (20 to 40 mg/kg) or and it carries less risk for surgeon and wounds, howe ver some have advo c a t e d xylazine hyd rochloride (0.3 to 0.5 patient. Various drugs and drug combi- p r i m a ry closure .7,8 Pr i m a ry closure is mg/kg) and butorphanol tartrate (0.01 nations have been recommended for this r a rely suited for castrations perf o r m e d to 0.05 mg/kg) provides reliable seda- procedure.2,5 The placement of a jugular in the field but may be of benefit in tion and analgesia.6 catheter is warranted for drug adminis- select cases where castration is

430 Aust Vet J Vol 77, No 7, July 1999 Clinical p e rformed aseptically in a surgical culated before emasculating the parietal s u p e rficial inguinal ring.5 A l t e r n a t i ve l y, facility. Reported advantages of primary tunic and cremaster muscle. In another a 8 to 15 cm incision can be made c l o s u re include early return to work , modification the surgeon’s thumb can be d i rectly over the superficial inguinal minimal postoperative management and placed through the incision made in the r i n g .1 1 A scrotal incision results in less a more favourable and early cosmetic parietal tunic and the fingers used to skin haemorrhage and precludes the outcome with no possibility of eve n t r a- p rolapse the testicle, vessels and ductus need to displace inguinal fat to locate tion.7 d e f e rens through the incision. T h i s the superficial inguinal ring.11 Re c o g n i- p rovides the surgeon with a secure grip tion of anato-mical features is improved Open technique on the parietal tunic. The vessels and if haemorrhage is controlled. Du r i n g Two incisions are made through the ductus deferens can then be emasculated dissection down to the inguinal ring the s c rotal skin, tunica dartos, scrotal fascia separately prior to emasculation of the smooth, white parietal tunic of the and parietal tunic parallel to the median parietal tunic and cremaster muscle or vaginal process is sought. If no structures raphe, approximately 2 cm apart and 8 the cord can be emasculated in one.5 a re identified the inguinal extension of to 10 cm long. The testis is pro l a p s e d the gubernaculum testis (scrotal liga- out of the tunic but remains attached to ment) can often be identified exiting the parietal tunic by the ligament of the Cryptorchid castration The failure of the right and left testicle from the superficial inguinal ring. It is a epididymis (Figure 1). This ligament can to descend occurs with nearly equal thin, flat, fibrous band that courses from be transected to release the parietal tunic frequency.9,10 Of left testicles that fail to the vaginal process to the scrotum. It can and cremaster muscle and expose the descend 75% are found within the be located by carefully inspecting the vessels and ductus deferens which can abdomen compared to 42% of right lateral or medial margins of the cranial then be emasculated. To reduce the t e s t i c l e s .1 0 Fa i l u re of both testicles to t h i rd of the superficial inguinal ring.1 4 o c c u r rence of postoperative complica- descend is uncommon, affecting 9 to Gentle traction on this ligament using tions such as scirrhous cord and hyd ro- 14% of cryptorchid horses.5,10 sponge forceps will eve rt the va g i n a l cele, it is desirable to digitally strip the An accurate castration history is p rocess from the superficial inguinal fascia around the parietal tunic as far helpful in determining the surgical ring and it can be opened longitudinally p roximal as possible so it may be emas- a p p roach to the cry p t o rchid horse.5 , 1 1 using scissors. Commonly the tail of the culated and re m ove d .2 , 5 This is easily Palpation of the scrotum and inguinal epididymis is the first stru c t u re identi- a c h i e ved if the parietal tunic alone (not rings for presence of testicular structures fied and gentle traction on the the parietal tunic and testicle together) is may require sedation in younger or more epididymis will expose the ductus pulled distally with Carmalt forc e p s anxious colts.5 Tr a n s rectal examination d e f e rens, the proper ligament of the while the fascia is stripped prox i m a l l y generally contributes little to differe n t i- testis, and finally the testis. using gauze swabs. Alternatively the ating the type of cryptorchid and carries If the vaginal ring can accommodate parietal tunic, the cremaster muscle, the i n h e rent risks in younger or more frac- m o re than the tips of the index and vessels and the ductus deferens can all be tious animals.5,11 middle fingers then the inguinal canal emasculated together. Surgical options include inguinal, should be packed with sterile gauze for Closed technique parainguinal, suprapubic paramedian 24 to 36 h or closed with sutures to Incisions similar to those for the open and flank appro a c h e s.2 , 5 Mo re re c e n t l y, reduce the risk of intestinal pro l a p s e technique are made down to but not standing and recumbent cry p t o rc h i d e c- t h rough the canal. A sterile gauze t h rough the parietal tunic (Fi g u re 2). tomy using a laparoscopic technique bandage can be used as packing to oblit- The testicle, still encapsulated by the have been described.12,13 erate the inguinal canal and the distal tunic, is grasped and the scrotal fascia is end is left hanging freely from the stripped from the parietal tunic using a Inguinal approach s c rotal wound. The pack is maintained dry swab, until the cremaster muscle and Two approaches are described for in the inguinal ring by loosely suturing the parietal tunic are clearly exposed. inguinal exploration.5,11 A 10 cm inci- skin edges. Alternatively the superf i c i a l The entire spermatic cord is then emas- ring can be sutured closed using simple culated.2,5 i n t e r rupted sutures of heavy absorbable Surgical approaches for cryptorchid suture material. Half-closed technique horses The approach is similar to the closed Parainguinal approach technique, howe ver after the parietal Inguinal W h e re the testis cannot be exteri- tunic and the cremaster muscle are Parainguinal orised from the inguinal canal using exposed a 2 to 3 cm ve rtical incision is Suprapubic paramedian n o n i n va s i ve inguinal appro a c h e s ,1 0 made through the parietal tunic just Flank s e veral more inva s i ve techniques have p roximal to the testicle. The inside of Laparoscopic been described to explore the inguinal the parietal tunic is inspected to ensure c a n a l .5 , 1 1 These have been used t h e re is no evidence of herniated intes- commonly but it has been suggested tine and the entire spermatic cord is sion is made through the scrotal skin that they increase the risk of eviscera- 10,11 emasculated prox i m a l l y. Alternative l y w h e re the testicle should be and digital t i o n . The parainguinal appro a c h the vessels and ductus can be exteri- dissection is continued tow a rds the p rovides a convenient alternative where orised from the parietal tunic and emas- the noninva s i ve inguinal appro a c h e s

Aust Vet J Vol 77, No 7, July 1999 431 Clinical h a ve been unsuccessful.15 A 4 cm inci- Laparoscopy s u r g e ry and subsiding by 9 days.2 0 sion is made in the aponeurosis of the Laparoscopic techniques for castration Excessive swelling is a common compli- external abdominal oblique muscle 1 to of cryptorchid horses have recently been cation and typically occurs with inade- 2 cm medial and parallel to the superfi- d e s c r i b e d .1 2 , 1 3 L a p a roscopy re q u i re s quate wound drainage, inadequate post- cial inguinal ring. The incision is special instruments not readily ava i l a b l e o p e r a t i ve exe rcise, poor lymphatic c e n t red over the cranial aspect of the in general practice5 and further re f i n e- drainage, exc e s s i ve surgical trauma or ring. The internal abdominal oblique ments are needed in the method.13 At infection.1,20 muscle underlying the aponeurosis is present this technique has limited appli- Postoperative swelling can be reduced bluntly separated along its muscle fibres cation in general practice but it may be by creating a large scrotal incision, to expose the peritoneum which is then more feasible in the future.5 a voiding exc e s s i ve tissue trauma, penetrated to enter the abdominal re m oving as much tunica vaginalis as cavity. The internal inguinal ring can be Monorchidism possible, manually stretching the surgical identified caudolaterally and, with a Mo n o rchidism is the complete incision and removing the median raphe sweeping action, the fingers should pick absence of one testicle and is rare in the during surgery.5,20 Following castration, up any testicular stru c t u res. These can h o r s e .5 A definitive diagnosis can only exercise, hosing the wound, and the use be exteriorised and emasculated. If diffi- be made after surgical exploration of the of nonsteroidal anti-inflammatory drugs culty is encountered in locating the abdomen, re m oval of the other testis can reduce swe l l i n g .1 , 5 , 2 0 The ow n e r epididymis or associated stru c t u res the and hormonal testing.1 8 , 1 9 Us e f u l may start riding the horse 24 to 48 h incision can be enlarged to allow the hormonal assays include basal plasma or after surgery.20 s u r g e o n’s hand to enter the abdominal s e rum testosterone and oestro n e Exc e s s i ve postoperative swelling is cavity for exploration of the uro g e n i t a l sulphate concentrations, testostero n e painful and reduces willingness to exe r- tract. The incision in the aponeurosis is concentrations following hCG stimula- cise, causing the wound to seal pre m a- closed using heavy absorbable suture s tion, and faecal oestrone sulphate t u rely and compounding the pro b l e m . and the subcutaneous tissue and skin c o n c e n t r a t i o n .5,18,19 The hCG stimula- Treatment invo l ves nonsteroidal anti- can be closed or left open to heal by tion test in horses older than 18 months, inflammatory drugs to decrease pain and second intention.15 basal oestrone sulphate assay in horses inflammation and increase tolerance to older than 3 years or a combination of e xe rc i s e .1 , 5 , 2 0 If scrotal wounds have Suprapubic paramedian approach closed, it may be beneficial to sedate the An incision of 8 to 15 cm is made horse and reopen the wounds manually cranially from the level of the pre p u t i a l Hormonal assays detecting testicular tissue wearing a sterile glove .1,5,20 This may orifice approximately 5 to 10 cm lateral need to be repeated on consecutive days 5 , 1 6 Hormone detected Sample to the ventral midline. The abdom- until the swelling reduces. Antimicrobial inal tunic, which is closely adherent to Basal testosterone Serum or plasma d rug treatment may be indicated where the ventral sheath of the rectus abdo- Basal oestrone Serum, plasma or the discharge is purulent. Se c o n d a ry minis muscle, is incised longitudinally sulphate faeces problems associated with severe swelling and the underlying fibres of the re c t u s Testosterone following Serum or plasma include phimosis, paraphimosis, cellulitis, hCG stimulation abdominis muscle are bluntly separated wound infection and dysuria.20 in the same direction. Blunt dissection is used to penetrate through the dorsal both tests appear to be most re l i- Excessive haemorrhage rectus sheath, re t roperitoneal fat and a b l e .5 , 1 1 , 1 8 , 1 9 The hCG stimulation test Haemorrhage may occur during, peritoneum. The testicle is usually m e a s u res plasma or serum testostero n e immediately after or several days after found near the deep inguinal ring and is concentrations, before and 1 and 24 h s u r g e ry.2 0 Some bleeding from scro t a l easily exteriorised. After emasculation, after intravenous administration of 6000 wounds after castration is normal but if the abdominal tunic, the subcutis and to 10,000 IU of hCG.18 , 1 9 Th e r e should pr ofuse bleeding continues unabated for skin are each closed separately with be no increase above basal testostero n e m o re than 15 min haemorrhage should i n t e r rupted or continuous sutures. T h i s concentrations in horses with no testic- be considered exc e s s i ve .1 , 5 , 2 0 Exc e s s i ve p ro c e d u re has largely been superseded ular tissue. The response in horses with haemorrhage generally occurs from the by the parainguinal approach, howe ve r testicular tissue may be poor during testicular arte r y, but may originate from it is proposed to allow access to both winter or if testicular tissue is abdominal. traumatic ru p t u re or laceration of testicles in the case of a bilateral cry p- branches of the external pudendal 5 Both tests should be performed if either torchid. test is inconclusive. Samples should be vei n . 1, 2 0 Ar terial haemorrhage is generally a result of inadequate crushing by the Flank approach submitted to laboratories that ro u t i n e l y emasculators. The emasculators should be A standard flank approach can be used assay equine testosterone and oestro n e applied perpendicular to, and without in standing or recumbent horses.17 T h e sulphate concentrations so that re l i a b l e 14 , 1 9 tension on, the spermatic cord with the testicle is located and re m oved using a ref e r ence values are avai l a b l e . cutting blade closest to the testes.1, 5 , 2 0 similar technique to the paramedian Precise guidelines for when to inter- a p p roach. This technique is less accept- Complications of castration vene surgically are not established but able cosmetically than the other Postoperative swelling treatment of postoperative haemorrhage approaches and is now generally reserved Some preputial and scrotal oedema is is best performed under general anaes- for removal of large neoplastic testicles.5 normal, usually greatest 3 to 6 days after

432 Aust Vet J Vol 77, No 7, July 1999 Clinical

into a sling and the horse anaesthetised tively.5,21 Extension of the septic process Complications of castration and positioned in dorsal re c u m b e n c y.2 1 t h rough the inguinal ring and into the Postoperative swelling In the field the intestine should be peritoneal cavity is possible but 5 Excessive haemorrhage l a vaged and where possible placed back u n c o m m o n . Treatment of scirrhous within the scrotum which is suture d .2 1 Eventration c o rd re q u i res surgical resection and Bro a d s p e c t rum antimicrobial therapy a n t i m i c robial therapy.1 , 5 , 2 0 The horse Funiculitis should be initiated, an analgesic dose of should be anaesthetised and positioned Hydrocele flunixin meglumine administered and in dorsal re c u m b e n c y. The infected Penile damage the horse immediately re f e r red to a stump is then isolated from healthy Continued masculine behaviour surgical facility.To replace the intestines tissue using blunt dissection. The cord is into the abdomen, dilation of the emasculated proximal to the infected vaginal ring and traction on the stump and the wound is left to heal by 5 1 , 5 , 2 0 intestines through ventral midline or second intention. t h e s i a . Be f o re anaesthesia the parainguinal celiotomy are usually patient should be assessed care f u l l y, n e c e s s a ry.5 , 2 1 The tunic should be Peritonitis paying particular attention to cardiovas- ligated and emasculated as far prox i- The vaginal and peritoneal cavities cular status. The site of haemorrhage mally as possible and the superf i c i a l communicate and nonseptic peritonitis should be identified. The spermatic cord inguinal ring closed with large-diameter, is common following castration.1 , 5 , 2 1 may be grasped with long forceps passed absorbable suture material.1,5,20 Alterna- Haemoperitoneum and secondary into the inguinal canal and the testicular ti ve l y , the inguinal canal can be packed inflammation can increase peritoneal a rt e ry occluded. The cord can then be with gauze for 24 to 48 h, howe ve r total nucleated cell counts to more than emasculated proximally or ligated. If the intestine may still eventrate around the 10 x 109 cells/L for at least 5 days with c o rd cannot be ligated or emasculated, p a c k i n g .1,5,21 Prolapse of the omentum counts greater than 100 x 109 cells/L not the forceps can be left in place for 12 to through the inguinal ring can usually be uncommon.23 Septic peritonitis is rare,1 24 h to allow thrombosis to occur. managed using sedation and transecting but should be considered where signs W h e re the end of the cord cannot be the prolapsed omentum as far prox i- include abdominal pain, pyrexia, tachy- grasped, haemorrhage can usually be mally as possible. After re c ove ry fro m cardia, diarrhoea, weight loss and reluc- c o n t rolled by packing the scrotum with anaesthesia the horse should be kept tance to move .1 , 5 , 2 1 Toxic or degenerate g a u ze. If the haemorrhage is occurring quiet in a stall for 24 to 48 h.5,21 n e u t rophils and intracellular bacteria f rom a large superficial vein in the Evisceration of omentum from the found on abdominocentesis confirm the s c rotal or inguinal area, ligation of the scrotal wound is much less serious and is d i a g n o s i s .1 , 5 , 2 1 Cu l t u re of a peritoneal vessel is the treatment of choice. best treated with transection of the fluid sample is suggested where possible. omentum which can be performed with Treatment consists of appro p r i a t e Eventration the horse standing.5 a n t i m i c robial and nonsteroidal anti- Eventration through the vaginal ring i n f l a m m a t o ry therapy, and prov i d i n g and open scrotal incision is uncommon, Funiculitis analgesia, peritoneal drainage and generally occurring within 4 h but may l a vage, and adequate drainage thro u g h 21 Funiculitis refers to inflammation of occur up to 6 days after surgery. Even- the spermatic cord .1 , 5 , 2 1 It is usually a the scro t u m .5 Until culture re s u l t s tration of the small intestine makes up septic process developing as an extension become available, procaine penicillin 67% of cases while omental pro l a p s e (20 mg/kg IM twice daily) and gentam- 2 2 of a scrotal infection or from a contami- comprises the re m a i n d e r. A surv i va l nated emasculator or ligature.5 Failure to icin sulphate (6.6 mg/kg, IV or IM once rate of 85 to 100% can be expected remove the tunica vaginalis and external daily) should be considered. w h e re appropriate treatment is insti- 2 2 c remaster muscle during open castra- t u t e d . Suggested predisposing factors tions predisposes horses to septic funi- Hydrocele A hyd rocele is an accumulation of include a pre-existing undetected c u l i t i s .2 3 Signs va ry with pyrexia, lame- sterile amber-coloured fluid within the inguinal hernia, presence of visceral ness, inguinal and scrotal swelling and vaginal tunic. It can appear months to s t ru c t u res adjacent to the internal c h ronic discharge often noted.1 , 5 T h e s e years following castration.1 , 5 , 2 1 It is inguinal ring, and increased abdominal may not develop for months or ye a r s 2 2 b e l i e ved to result from failure to re s e c t p re s s u re following surgery. Pa l p a t i o n after castration.5,21 the vaginal tunic adequately during of the scrotum and inguinal regions for In the early stages, funiculitis often castration and is reported to occur most hernias prior to castration is re c o m- re s o l ves with antimicrobial therapy and commonly in mules.1 , 5 It appears as a mended in foals. St a n d a rd b red horses the establishment of drainage, but occa- fluid-filled enlargement of the scro t u m a re believed to be predisposed to sionally surgical re m oval of the infected 5 that can often be reduced by squeez i n g congenital inguinal herniation. stump is re q u i re d .5 , 2 1 A chronic infec- the fluid into the abdominal cavity. If evisceration occurs the main objec- tion with pyogenic bacteria is Treatment is only necessary where the tive is to clean and protect the intestine commonly referred to as scirrhous cord, s welling is unsightly or interf e res with and return it to the abdomen before it is h owe ver the term ‘c h a m p i g n o n’ and function. The skin is incised over the sac e xc e s s i vely traumatised or contami- ‘ b o t r i o m yc o s i s’ have been used histori- 2 1 and the vaginal tunic is isolated prox i- n a t e d . The intestine should be cally to describe infection with St re p t o - p rotected by a moistened towel shaped mally to the inguinal ring and emascu- coccus spp and Staphylococcus spp, respec- lated.1,5

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Penile damage tion.3,26 It is likely that this is psycholog- 12. Davis E. Laparoscopic cryptorchidectomy in standing horses. Vet Surg 1997;26:326-331. Complications involving the penis are ical in origin and re p resents normal 13. Hendrickson DA, Wilson DG. Laparoscopic r a re and generally associated with iatro- social interaction between horses. Where cryptorchid castration in standing horses. Vet Surg genic trauma to the penile shaft. Pe n i l e this behaviour is excessive or the castra- 1997;26:335-339. p rolapse can occur secondary to exc e s- 14. Valdez H, Taylor TS, McLaughlin SA, Martin tion history is obscure, hormonal testing MT. Abdominal cryptorchidectomy in the horse s i ve swelling, and priapism and penile (see monorchidism) can be used to using inguinal extension of the gubernaculum paralysis has been re p o rted follow i n g establish whether testicular tissue is testis. J Am Vet Med Assoc 1979;174:1110-1112. administration of phenothiazine-deriva- present. 15. Wilson DG, Reinerston EL. A modified parain- 1,5,21 guinal approach for cryptorchidectomy in horses: tive tranquillizers. an evaluation in 107 horses. Vet Surg 1987;16:1- References 4. Continued masculine behaviour 1. Schumacher J. Complications of castration. 16. Cox JE, Edwards GB, Neal PA. Supra-pubic Castration does not always result in Equine Vet Educ 1996;8:254-259. paramedian laparotomy for abdominal cryp- elimination of objectionable stallion-like 2. Trotter GW. Castration. In: McKinnon AO, Voss torchidism in the horse. Vet Rec 1975;97:428-432. b e h a v i o u r. This has been attributed to JL, editors. Equine reproduction. Lea and Febiger, 17. Swift PN. Castration of a stallion with bilateral Philadelphia, 1993:907-914. abdominal cryptorchidism by flank laparotomy. incomplete re m oval of epididymal 3. Wilson JF, Quist CF. Professional liability in Aust Vet J 1972;48:472-473. tissue, presence of heterotopic testicular equine surgery. In: Auer JA, editor. E q u i n e 18. Arighi M, Bosu WTK. Comparison of hormonal tissue, production of high concentra- surgery. Saunders, Philadelphia, 1992:13-35. methods for diagnosis of cryptorchidism in horses. 4. Smith JA. The development and descent of the J Equine Vet Sci 1989;9:20-26. tions of androgens from the adre n a l testis in the horse. Vet Ann 1975;15:156-161. 19. Strong M, Dart AJ, Malikides N, Hodgson DR. gland, incomplete cryptorchid castration 5. Schumacher J. Surgical disorders of the testicle Monorchidism in two horses. Aust Vet J and psychological re a s o n s .1, 5 A n d ro g e n s and associated structures. In: Auer JA, editor. 1997;75:33-35. 20. Hunt RJ. Management of complications asso- are not produced by the epididymis and Equine surgery . Saunders, Philadelphia, 1992:674-703. ciated with equine castration. Compend Contin t h e re f o re the presence or absence of 6. Geiser DR. Chemical restraint and analgesia in Educ Pract Vet 1991;13:1835-1873. epididymal tissue cannot influence the horse. Vet Clin North Am Equine Pract 21. Hunt RJ, Boles Cl. Postcastration eventration masculine behaviour. Amputating the 1990;6:495-512. in horses: eight cases. Can Vet J 1 9 8 9 : 3 0 : 9 6 1 - 7. Palmer SE. Castration of the horse using 963. spermatic cords was re p o rted to abolish primary closure technique. Proc Am Assoc Equine 22. van der Velden MA, Rutgers LJE. Visceral objectionable masculine behaviour in Pract 1984;30:17-20. prolapse after castration in the horse: a review of 75% of castrated horses, but no satisfac- 8. Barber SM. Castration of horses with primary 18 cases. Equine Vet J 1990;22:9-12. 23. Schumacher DJC, Schumacher J, Spano JS et t o ry explanation was offered for this closure and scrotal ablation. Vet Surg 1 9 8 5 ; 1 4 : 2 - 6. al. Effects of castration on peritoneal fluid 24 re s p o n s e . He t e rotopic testicular tissue 9. Cox JE, Edwards GB, Neal PA. An analysis of constituents in the horse. J Vet Intern Med and production of adrenal andro g e n s 500 cases of equine cryptorchidism. Equine Vet J 1988;2:22-25. h a ve never been established in horses 1979;11:113-116. 24. Smith JA. Masculine behaviour in geldings. Vet 10. Stickle RL, Fessler JF. Retrospective study of Rec 1974:94:160-161. and are unlikely to be the cause of 350 cases of equine cryptorchidism. J Am Vet Med 25. Line SW, Hart BL, Sanders L. Effect of prepu- 1 , 5 continued stallion-like behaviour. Assoc 1978;172:343-346. bertal versus postpubertal castration on sexual About 20 to 30% of horses display some 11. Cox JE. Cryptorchid castration. In: McKinnon and aggressive behaviour in male horses. J Am Vet Med Assoc 1985;186:249-251. masculine behaviour following castra- AO, Voss JL, editors. Equine reproduction. L e a and Febiger, Philadelphia, 1993;915-920. (Accepted for publication 21 December 1998)

Erysipelas in malleefowl

DJ BLYDE and R WOODS Western Plains Zoo, PO Box 831 Dubbo, New South Wales 2830

he malleefowl (Leipoa ocellata) is mound, or in heaps of fermenting a p p reciably since Eu ropean settlement.2 a gro u n d - d welling Au s t r a l i a n vegetable material built up for this Factors influencing this decline include Tn a t i ve bird originally found in a purpose (Fi g u re 1). The incubation land clearance for cropping and range of habitats. It belongs to the p rocess utilises external sources of heat pastoralism, predation by the Eu ro p e a n mound-building family of birds, the such as decomposing vegetation or inci- f ox ( Vulpes vulpes), changes in fire Megapodiidae, which are confined dent solar radiation. The adults keep the f re q u e n c y, grazing of malleefow l almost entirely to the Australian region. eggs at a constant temperature by communities by domestic stock, and the Members of this family va ry greatly in constantly remodeling the mound, p resence of introduced mammalian colour and form. However, they all have adding or removing dirt and leaves. The pests, particularly goats ( Ca p ra hirc u s ) in common the fact that they do not eggs hatch in the mound and the chicks and rabbits ( Oryctolagus cuniculus).3 No build a nest and brood their eggs, but a re left to look after themselve s .1 re p o rts of disease as a factor in the b u ry them in the ground, or in a Numbers of malleefowl have declined decline of the malleefowl are ava i l a b l e

434 Aust Vet J Vol 77, No 7, July 1999