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EQUINE VETERINARY EDUCATION / AE / MARCH 2016


Original Article Inguinal percutaneous ultrasound to locate cryptorchid testes


R. P. C. Coomer*†, D. A. Gorvy‡, S. A. McKane† and H. Wilderjans§ †Cotts Equine Hospital, Narberth, Pembrokeshire, UK; ‡Str€


§Dierenkliniek De Bosdreef, Moerbeke-Waas, Belgium. *Corresponding author email: richcoomer@hotmail.com D. A. Gorvy’s present address: M€


alaren H€ Keywords: horse; cryptorchid; castration; ultrasound; inguinal


Summary Standing laparoscopic removal of abdominally retained cryptorchid testes may reduce patient morbidity and speed recovery compared with traditional laparotomy because anaesthesia is avoided and skin incisions are smaller. Reliably locating the testis preoperatively is therefore optimal to avoid unnecessary surgical morbidity and expense. We describe and review the results of a simple method of location using ultrasound scanning of the inguinal region, with a negative result indicating abdominal retention. One hundred and twenty-seven horses with 141 cryptorchid testes were identified. Eighty-five testes were identified inguinally: 56 abdominal. Two inguinally retained testes were not observed on ultrasound (false negatives) and 2 testes were considered inguinal but subsequently had to be removed from the abdomen (false positives). Sensitivity of inguinal ultrasound to predict the location of cryptorchid testes was therefore 98% and specificity 97%. The technique described herein proved a reliable technique to locate cryptorchid testes prior to surgery, minimising morbidity and cost. Suspect cryptorchids with no external evidence of testes should undergo a screening blood test prior to this ultrasound method of diagnosis.


Introduction


Cryptorchid, literally meaning ‘hidden testis’, occurs when one or both testes fail to descend from the abdomen into the scrotum (Law 1923). Affected animals have a variety of colloquial names, including rig, ridgling and original.As cryptorchidism is variously considered heritable (Stout 2013), affected horses are regarded as genetically unsound and cannot be used for breeding by most organisations (Haynes 1986).


Castration is necessary to abolish the adverse behavioural


characteristics in these animals and this procedure is more technically demanding than routine castration. Traditionally, the inguinal area is searched first before moving to the abdominal cavity (Cox et al. 1975). Laparoscopy offers significant advantages over traditional laparotomy approaches, including improved visualisation, reduced patient morbidity through smaller incisions and a more rapid post operative recovery (Fischer and Vachon 1993). Recent data have questioned this premise. Laparoscopic cryptorchidecomy carried out under general anaesthesia was found to have significantly longer surgery times and experienced higher rates of post operative complication compared with traditional open surgery (Cribb et al. 2015). Laparoscopy can also be carried out under standing sedation, avoiding the increased morbidity and cost associated with


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general anaesthesia (Hendrickson and Wilson 1997) as well as facilitating finding the testis during surgery (Hendrickson 2002). No objective published data currently exist comparing standing laparoscopic with traditional techniques, but with significant experience of both, it is the current authors’ experience that standing laparoscopic cryptorchidectomy is a rapid technique with few complications. Ascertaining the location of hidden testes, especially prior


to making a standing approach, minimises the surgical morbidity and cost of cryptorchid castration. In bilateral cryptorchid horses where the possibility of previous surgery exists, active testicular tissue is first identified using a hormonal assay (Cox et al. 1986). In these and in unilateral cryptorchids, the location of the missing testis can then be ascertained by rectal examination (Cox et al. 1986), by ultrasound examination per rectum (Jann and Rains 1990) or per cutaneous (Schambourg et al. 2006). Rectal examination may be dangerous and/or impossible in ponies; however, the percutaneous technique is appropriate in most cases. It is these authors’ experience that reliably visualising and locating an abdominal testis using a previously described percutaneous technique is more difficult than described (Schambourg et al. 2006). Therefore, we simplified the technique to scan only the inguinal region; absence of a testis was considered to indicate abdominal retention. It is the purpose of this paper to describe this simplified technique and its results when applied to cryptorchid horses presented to 3 hospitals for castration.


Materials and methods


Horses presented for cryptorchid castration at 3 equine referral hospitals between June 2008 and January 2015 were identified retrospectively and case records reviewed.


Imaging technique Inguinal ultrasound examination was carried out in all cases on initial presentation. Heavy sedation was induced using intravenous administration of a routine a2-agonist and opiate drug combination. Horses were restrained in stocks and an initial manual palpation of the scrotal and inguinal region was carried out. The skin in this area was liberally soaked with propanol or surgical spirit for ultrasound coupling. The ultrasound probe was applied to the inguinal area in a longitudinal orientation (Fig 1): three authors used a 2–4 MHz curvilinear ultrasound probe set at 8 cm (Fig 2) depth; one author used an 8–13 MHz linear probe set at 6 cm depth (Fig 3). The scrotal and connective tissue abaxial to the penile shaft and external to the superficial inguinal ring were


astklinik, Sigtuna, Sweden. omsholm Equine Hospital, Str€ omsholm, Sweden; and


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