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Testicular prosthesis in a Quarterhorse stallion: A case report
ELSEVIER
TESTICULAR
PROSTHESIS IN A QUARTERHORSE A CASE REPORT
STALLION:
N.R. Perkins,1 G.S. Frazer 2 and W.R. ThrelfalP ‘Department of Veterinary Clinical Sciences Massey University, Palmerston North, New Zealand 2Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH 43210, USA Received for publication: Accepted:
Apri 1 I 1, I 995 June 9, 1995
ABSTRACT A testicular prosthesis was surgically removed from the scrotum of a Quarterhorse stallion presented for evaluation of a large, firm, unilateral scrotal mass. The prosthesis was constructed from methyl methacrylate moulded around a roll of fiberglass casting tape. The prosthesis had been surgically implanted in the scrotum approximately 4 yr prior to presentation in order to give the appearance of 2 testicles in the scrotum for showing and breeding purposes. The horse had been used to successfully breed mares prior to presentation and produced 4.046 x 109 progressively motile, morphologically normal spermatozoa in an ejaculate collected 4 mo after surgery to remove the prosthesis. Ethical issues raised by this case are discussed. Key words: testicular, prosthesis, scrotum, stallion INTRODUCTION The use of a testicular prosthesis in an equine cryptorchid to disguise the abnormal scrotal appearance and allow continued showing has been previously reported (5). In that case a commercially produced, silicone filled, human mammary implant was removed from the scrotum of a cryptorchid horse (5). Silicone implants produce a compliant feel on palpation which is similar in consistency to a normal testis, but it should be noted that there is no associated epididymis or spermatic cord. A normal testis should feel smooth, compliant and free of nodules (8). The head, body and tail of the attached epididymis should be smooth and discrete (8). Cryptorchidism is defined as a congenital condition in which one or both testicles fail to descend into the scrotum (8). Affected stallions are generally considered to be undesirable, primarily because of the suspected heritable nature of the condition (3). The rules of the American Quarterhorse Association prohibit registration of offspring from a cryptorchid stallion if the animal was foaled after January 1, 1985 (5). Cryptorchidism is more common in certain horse breeds, notably the Quarterhorse, American Saddlebred and Percheron (4). The diagnosis of cryptorchidism in a horse that has not been castrated is essentially dependent on external palpation of the scrotal contents with detection of the absence of one or both testicles (6). Such horses are likely to be cryptorchids with the retained testicle being abdominal, ectopic or inguinal since gonadal agenesis is extremely rare in the horse (8). This case report describes the removal from the scrotum of a testicular prosthesis constructed from methyl methacrylate moulded around a 12.5-cm roll of fiberglass casting tape. This report is considered to be of interest in that it documents an inappropriate approach to the management of a suspected cryptorchid horse.
Theriogenology 45:535-540, 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 100 10
0093-691 X/96/$1 5.00 SSDI 0093-691X(95)00400-9
536
Theriogenology CASE PRESENTATION
A 6-yr-old, Quarterhorse stallion was referred to the Ohio State University Veterinary Teaching Hospital, for examination of an enlarged, fii, scrotal mass. The stallion had been purchased by the current owner 4 yr prior to presentation. During the previous 4 yr the stallion had been shown as an intact horse and used as a commercial, breeding stallion. The scrotal enlargement was noticed when the stallion was transferred to a new trainer 4 wk prior to presentation at our facility. The stallion was found to be in good physical condition and no abnormalities were found upon general physical examination. The left side of the scrotum contained a hard mass with the consistency of bone. The mass was 7 cm wide at the widest point, 18 cm long and 9.2 cm in height, with a circumference of 45 cm. The scrotal skin was freely movable over the mass. Deep palpation above the mass revealed a thin, cord like structure in the area of the spermatic cord. The mass was uniformly dense and no structure that resembled an epididymis could be palpated. The right testicle was 5.5 cm wide at the widest point, 8.5 cm long and 6.5 cm high with a circumference of 29.3 cm. It was softer than normal and the mass in the left side of the scrotum appeared to be impinging on the right testicle. The right spermatic cord and epididymis were readily identified by palpation. Ultrasonographic examination allowed visualization of the right testicle, epididymis and spermatic cord, but the mass in the left side of the scrotum appeared as a single hyperechoic line with acoustic shadowing. This was interpreted as being due to complete attenuation of the ultrasonic beam, as might be expected if a dense mass such as mineralized bone were present in the left side of the scrotum. A tentative diagnosis of testicular teratoma was made and surgical removal of the mass recommended. Anesthesia was induced with a combination of guafenesin and thiamylal, followed by maintenance with halothane using a semi-closed circle apparatus. Dorsal recumbency was chosen to facilitate the surgical approach to the scrotum. After routine surgical preoperative procedures, a 20 cm skin incision was made over the mass. Blunt dissection through the subcutaneous fascia revealed a firm, organized, fibrous capsule. This was incised and the mass, having no blood supply, was easily removed from its position within the capsule. Sharp dissection through the deep layer of the fibrous capsule to the external inguinal ring revealed a vascular, cord like structure extending from the inguinal canal to the caudal, dorsal aspect of the capsule. No evidence of any other structure resembling a testicle was found on dissection of the inguinal ring area to the level of but not penetrating the internal inguinal ring. The mass measured approximately 7 by 18 cm and was oval or slightly elliptical in shape (Figure 1). The external surface was light tan in color and had numerous small indentations on the surface. A survey radiograph of the removed mass (Figure 2), revealed an oval shaped object with an irregular margin that appeared to have mineral consistency and a focal radiolucent area centrally. A mottled or granular, cylindrical shaped structure with the appearance of a roll of fiberglass casting material was seen in the mid portion of the oval outer shell. The entire mass appeared to be exogenous in origin and was thought to be a molded acrylic (methyl methacrylate) shell containing a roll of 125cm fiberglass casting material. Due to the potentially fraudulent nature of the case, further surgical exploration in search of a cryptorchid testicle was discontinued. To prevent ascending infection, the deep layer of the fibrous capsule was sutured using 2/O polydioxanone (PDS), in a simple continuous pattern. The superficial capsule and scrotal skin were not sutured, thereby facilitating drainage and subsequent healing by secondary intention. At the completion of surgery the scrotal skin was closely examined for evidence of a previous surgery. An g-cm scar resembling the site of a previously sutured, surgical incision was noted over the caudal aspect of the median raphe. The horse was treated with penicillin and gentamycin on the day of the surgery only. Treatment following surgery consisted of 10 min of hand walking twice each day, hydrotherapy, and application of Vaseline to the stallion’s legs. There was minimal exudation or swelling. The surgery site was cleaned daily for 4 d and the stallion discharged on the fifth day after surgery.
Theriogenology
Fig we
Photograph of mass surgically removed from the left side of the scrotum of a 6-yr-old Quarterhorse stallion. Impressions resembling finger marks made dmring moulding of the methyl methacrylate may be seen on the surface of the mass.
538
Figul re 2. Survey radiograph of mass removed from the scrotum of a 6-yr-old Quarterhcxse stallion. The mass contains a radiodense object resembling a 12.5-cm roll of fiberglass casting tape. Bar = 1 cm.
Theriogenology
539
The horse was re-evaluated 4 mo post operatively. The right testicle was normal in consistency on palpation and measured 33 cm in circumference. A semen sample was collected using a Missouri style artificial vagina. The stallion showed good libido and had no difficulty in mounting a phantom mare. Fifty milliliters of gel free semen were collected containing 60% progressively motile spermatozoa and 41% morphologically normal spermatozoa, with a concentration of 329 million spermatozoa per ml (equivalent to 4.046 x 109 morphologically normal, progressively motile spermatozoa). DISCUSSION It is considered very likely that the stallion was a cryptorchid and that the prosthesis was placed in the scrotum so that the stallion would meet the breed registry requirements of having 2 testicles in the scrotum for showing and breeding purposes. Further enquiries regarding the history of the case were made following the surgical findings. The owner and previous trainer were unaware of the existence of a scrotal abnormality. No-one had palpated the stallion’s scrotum during the previous 4 yr while he was shown and used as a breeding stallion. The problem was only noticed when the animal changed trainers and the new trainer evaluated the animal’s scrotum and gait. Them was no history of a previous traumatic or medical condition involving 1 scrotal testicle which could have warranted surgical removal. Neither was there documentation of any prior surgery involving the scrotum having been performed. The presence of a surgical scar on the scrotum suggested a previous surgery involving that area - probably to place the prosthesis within the scrotum. However, this could not be confirmed. Unfortunately, a definitive diagnosis of cryptorchidism was not made in this case since the owners did not wish to have further procedures performed to determine whether the left testicle was present within the abdomen. The tentative diagnosis of testicular teratoma in this case was based on the palpable and ultrasonographic characteristics of the scrotal mass. Testicular neoplasia is often associated with nonpainful enlargement of the affected testicle, and the testicular contour is abnormal and firm (8). Testicular teratomas arise from multipotential embryonic tissue and are considered to be the most common type of equine testicular tumor. Teratomas contain derivatives from one or more of the 3 germ cell layers (ectoderm, endoderm and mesoderm) and as such may have a variety of tissue types present, including dermal, alimentary, cartilaginous, musculoskeletal and respiratory (2,7,8). The presence of bone in equine testicular teratomas is considered to be common. Although teratomas may occur in scrotal testicles, they are more common in a retained testis. Other causes of a unilateral scrotal mass include testicular torsion, orchitis, periorchitis, varicocele, testicular hematoma, hematocele and scrotal hernia (8). Cryptorchidism is the most common disorder of sexual development in male horses, arising from abnormal embryological development and descent of the equine fetal testis (8). The retained testis or testes may be abdominal, inguinal or subcutaneous (often termed an ectopic testicle; 3). In one study, 17% of 2- to 3-yr-old colts referred to veterinary hospitals were diagnosed as being cryptorchid (4). Although suspected of being heritable, equine cryptorchidism is likely to be a complex developmental condition sensitive to abnormal numbers of a wide array of genes located on many different chromosomes (8). The testes usually enter the inguinal canal between 270 and 300 d of gestation, and are found within the scrotum between 30 d prior to and 10 d after birth (1). During the first 2 wk after birth, the internal inguinal canal constricts and fibroses and essentially prevents the testes from entering or leaving the scrotum after that time (3). Unilateral testicular retention is 9 times more common than bilateral, with the right and left testicles involved at about equal frequency (8). Retained left testicles are more likely to be located abdominally than inguinally, whereas retained right testicles are more commonly within the inguinal region. This is thought to be due to the slightly larger size of the left testicle making it more likely to resist access to the inguinal canal and therefore to be retained abdominally (8). Cryptorchids may present as intact horses, containing either no testes or one scrotal testis. A more common presentation is an apparent gelding with a history of stallion like
540
Theriogenology
behaviour. These cases may be true bilateral cryptorchids, but often are the result of inappropriate surgical intervention in that only the descended testicle has been removed. Diagnosis in such cases depends on careful examination of the scrotum and it’s contents, deep external palpation of the external inguinal ring and palpation per rectum of the ventral abdomen in the vicinity of the appropriate internal inguinal ring. Transinguinal and transrectal ultrasonography is also useful in locating a cryptorchid testicle since the ultrasonographic appearance of a testicle is characteristic (8). Endccrinological testing is widely used to diagnose cryptorchidism. The most common test (8) is to compare serum testosterone concentrations before and after intravenous administration of 6 to 12,000 IU hCG (Follutein, Solvay Veterinary, Inc., Princeton NJ, USA). A single serum sample may be assayed for estrogen concentration in animals older than 3 yr of age, since horses with testicular tissue produce high levels of estrogens (8). This case raises a number of important issues. First, professional ethics is of concern since it is possible that a veterinarian intervened to make the animals appearance comply with breed association guidelines. Second, the presence of abnormal scrotal contents should have been detected at a prepurchase examination prior to the current owner purchasing the horse. A prepurchase examination of a stallion being considered for show and breeding purposes should include examination of the scrotum and contents by palpation. It is not known whether such an examination was performed. Third, the fact that this horse was capable of propagating a potentially heritable trait is cause for concern. Finally, complications have been reported previously following placement of an implant in a stallion’s scrotum (5). These include infection, development of draining tracts, scrotal inflammation and possibly adverse effects on the contralateral testicle due to scrotal hyperthermia from the local inflammatory response (5). The scrotum in this case showed no evidence of infection. A thick fibrous capsule had developed around the implant, but there appeared to be little effect on the function of the contralateral testis, as determined by subsequent semen analysis. REFERENCES 1. Amann R. Physiology and Endocrinology. In: McKinnon A, Voss J (eds), Equine Reproduction. Philadelphia, Lea and Febiger, 1993; 677-679. 2. Caron J, Barber S, Bailey J. Equine tesicular neoplasia. Comp Cont Ed 1985;7:S53-S59. 3. Genetzky R, Shira M, Schneider E, Easley J. Equine cryptorchidism: Pathogenesis, diagnosis and treatment. Comp Cont Ed 1984;6:S577-S582. 4. Hayes M. Epidemiological features of 5009 cases of equine cryptorchidism . Eq Vet J 1986;18:467-471. 5. Himichs K, Gentile D, Hurtgen J, Richardson D. Complications from a testicular prosthesis in a stallion. JAVMA 1985;186:390-391. 6. Leipold H, DeBowes R, Bennett S, Cox J, Clem M. Cryptorchidism in the horse: genetic implications. Proc AM Mtg AAEP 1986;579-589. 7. Peterson D. Equine testicular tumors. J Eq Vet Sci 1984;4:25-27. 8. Vamer D, Schumacher J, Blanchard T, Johnson L. Diseases of the testes. In: Varner D, Schumacher J, Blanchard T and Johson L (eds), Diseases and Management of Breeding Stallions. Goleta, CA, American Veterinary Publications, 1991; 193-204.
TESTICULAR
PROSTHESIS IN A QUARTERHORSE A CASE REPORT
STALLION:
N.R. Perkins,1 G.S. Frazer 2 and W.R. ThrelfalP ‘Department of Veterinary Clinical Sciences Massey University, Palmerston North, New Zealand 2Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH 43210, USA Received for publication: Accepted:
Apri 1 I 1, I 995 June 9, 1995
ABSTRACT A testicular prosthesis was surgically removed from the scrotum of a Quarterhorse stallion presented for evaluation of a large, firm, unilateral scrotal mass. The prosthesis was constructed from methyl methacrylate moulded around a roll of fiberglass casting tape. The prosthesis had been surgically implanted in the scrotum approximately 4 yr prior to presentation in order to give the appearance of 2 testicles in the scrotum for showing and breeding purposes. The horse had been used to successfully breed mares prior to presentation and produced 4.046 x 109 progressively motile, morphologically normal spermatozoa in an ejaculate collected 4 mo after surgery to remove the prosthesis. Ethical issues raised by this case are discussed. Key words: testicular, prosthesis, scrotum, stallion INTRODUCTION The use of a testicular prosthesis in an equine cryptorchid to disguise the abnormal scrotal appearance and allow continued showing has been previously reported (5). In that case a commercially produced, silicone filled, human mammary implant was removed from the scrotum of a cryptorchid horse (5). Silicone implants produce a compliant feel on palpation which is similar in consistency to a normal testis, but it should be noted that there is no associated epididymis or spermatic cord. A normal testis should feel smooth, compliant and free of nodules (8). The head, body and tail of the attached epididymis should be smooth and discrete (8). Cryptorchidism is defined as a congenital condition in which one or both testicles fail to descend into the scrotum (8). Affected stallions are generally considered to be undesirable, primarily because of the suspected heritable nature of the condition (3). The rules of the American Quarterhorse Association prohibit registration of offspring from a cryptorchid stallion if the animal was foaled after January 1, 1985 (5). Cryptorchidism is more common in certain horse breeds, notably the Quarterhorse, American Saddlebred and Percheron (4). The diagnosis of cryptorchidism in a horse that has not been castrated is essentially dependent on external palpation of the scrotal contents with detection of the absence of one or both testicles (6). Such horses are likely to be cryptorchids with the retained testicle being abdominal, ectopic or inguinal since gonadal agenesis is extremely rare in the horse (8). This case report describes the removal from the scrotum of a testicular prosthesis constructed from methyl methacrylate moulded around a 12.5-cm roll of fiberglass casting tape. This report is considered to be of interest in that it documents an inappropriate approach to the management of a suspected cryptorchid horse.
Theriogenology 45:535-540, 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 100 10
0093-691 X/96/$1 5.00 SSDI 0093-691X(95)00400-9
536
Theriogenology CASE PRESENTATION
A 6-yr-old, Quarterhorse stallion was referred to the Ohio State University Veterinary Teaching Hospital, for examination of an enlarged, fii, scrotal mass. The stallion had been purchased by the current owner 4 yr prior to presentation. During the previous 4 yr the stallion had been shown as an intact horse and used as a commercial, breeding stallion. The scrotal enlargement was noticed when the stallion was transferred to a new trainer 4 wk prior to presentation at our facility. The stallion was found to be in good physical condition and no abnormalities were found upon general physical examination. The left side of the scrotum contained a hard mass with the consistency of bone. The mass was 7 cm wide at the widest point, 18 cm long and 9.2 cm in height, with a circumference of 45 cm. The scrotal skin was freely movable over the mass. Deep palpation above the mass revealed a thin, cord like structure in the area of the spermatic cord. The mass was uniformly dense and no structure that resembled an epididymis could be palpated. The right testicle was 5.5 cm wide at the widest point, 8.5 cm long and 6.5 cm high with a circumference of 29.3 cm. It was softer than normal and the mass in the left side of the scrotum appeared to be impinging on the right testicle. The right spermatic cord and epididymis were readily identified by palpation. Ultrasonographic examination allowed visualization of the right testicle, epididymis and spermatic cord, but the mass in the left side of the scrotum appeared as a single hyperechoic line with acoustic shadowing. This was interpreted as being due to complete attenuation of the ultrasonic beam, as might be expected if a dense mass such as mineralized bone were present in the left side of the scrotum. A tentative diagnosis of testicular teratoma was made and surgical removal of the mass recommended. Anesthesia was induced with a combination of guafenesin and thiamylal, followed by maintenance with halothane using a semi-closed circle apparatus. Dorsal recumbency was chosen to facilitate the surgical approach to the scrotum. After routine surgical preoperative procedures, a 20 cm skin incision was made over the mass. Blunt dissection through the subcutaneous fascia revealed a firm, organized, fibrous capsule. This was incised and the mass, having no blood supply, was easily removed from its position within the capsule. Sharp dissection through the deep layer of the fibrous capsule to the external inguinal ring revealed a vascular, cord like structure extending from the inguinal canal to the caudal, dorsal aspect of the capsule. No evidence of any other structure resembling a testicle was found on dissection of the inguinal ring area to the level of but not penetrating the internal inguinal ring. The mass measured approximately 7 by 18 cm and was oval or slightly elliptical in shape (Figure 1). The external surface was light tan in color and had numerous small indentations on the surface. A survey radiograph of the removed mass (Figure 2), revealed an oval shaped object with an irregular margin that appeared to have mineral consistency and a focal radiolucent area centrally. A mottled or granular, cylindrical shaped structure with the appearance of a roll of fiberglass casting material was seen in the mid portion of the oval outer shell. The entire mass appeared to be exogenous in origin and was thought to be a molded acrylic (methyl methacrylate) shell containing a roll of 125cm fiberglass casting material. Due to the potentially fraudulent nature of the case, further surgical exploration in search of a cryptorchid testicle was discontinued. To prevent ascending infection, the deep layer of the fibrous capsule was sutured using 2/O polydioxanone (PDS), in a simple continuous pattern. The superficial capsule and scrotal skin were not sutured, thereby facilitating drainage and subsequent healing by secondary intention. At the completion of surgery the scrotal skin was closely examined for evidence of a previous surgery. An g-cm scar resembling the site of a previously sutured, surgical incision was noted over the caudal aspect of the median raphe. The horse was treated with penicillin and gentamycin on the day of the surgery only. Treatment following surgery consisted of 10 min of hand walking twice each day, hydrotherapy, and application of Vaseline to the stallion’s legs. There was minimal exudation or swelling. The surgery site was cleaned daily for 4 d and the stallion discharged on the fifth day after surgery.
Theriogenology
Fig we
Photograph of mass surgically removed from the left side of the scrotum of a 6-yr-old Quarterhorse stallion. Impressions resembling finger marks made dmring moulding of the methyl methacrylate may be seen on the surface of the mass.
538
Figul re 2. Survey radiograph of mass removed from the scrotum of a 6-yr-old Quarterhcxse stallion. The mass contains a radiodense object resembling a 12.5-cm roll of fiberglass casting tape. Bar = 1 cm.
Theriogenology
539
The horse was re-evaluated 4 mo post operatively. The right testicle was normal in consistency on palpation and measured 33 cm in circumference. A semen sample was collected using a Missouri style artificial vagina. The stallion showed good libido and had no difficulty in mounting a phantom mare. Fifty milliliters of gel free semen were collected containing 60% progressively motile spermatozoa and 41% morphologically normal spermatozoa, with a concentration of 329 million spermatozoa per ml (equivalent to 4.046 x 109 morphologically normal, progressively motile spermatozoa). DISCUSSION It is considered very likely that the stallion was a cryptorchid and that the prosthesis was placed in the scrotum so that the stallion would meet the breed registry requirements of having 2 testicles in the scrotum for showing and breeding purposes. Further enquiries regarding the history of the case were made following the surgical findings. The owner and previous trainer were unaware of the existence of a scrotal abnormality. No-one had palpated the stallion’s scrotum during the previous 4 yr while he was shown and used as a breeding stallion. The problem was only noticed when the animal changed trainers and the new trainer evaluated the animal’s scrotum and gait. Them was no history of a previous traumatic or medical condition involving 1 scrotal testicle which could have warranted surgical removal. Neither was there documentation of any prior surgery involving the scrotum having been performed. The presence of a surgical scar on the scrotum suggested a previous surgery involving that area - probably to place the prosthesis within the scrotum. However, this could not be confirmed. Unfortunately, a definitive diagnosis of cryptorchidism was not made in this case since the owners did not wish to have further procedures performed to determine whether the left testicle was present within the abdomen. The tentative diagnosis of testicular teratoma in this case was based on the palpable and ultrasonographic characteristics of the scrotal mass. Testicular neoplasia is often associated with nonpainful enlargement of the affected testicle, and the testicular contour is abnormal and firm (8). Testicular teratomas arise from multipotential embryonic tissue and are considered to be the most common type of equine testicular tumor. Teratomas contain derivatives from one or more of the 3 germ cell layers (ectoderm, endoderm and mesoderm) and as such may have a variety of tissue types present, including dermal, alimentary, cartilaginous, musculoskeletal and respiratory (2,7,8). The presence of bone in equine testicular teratomas is considered to be common. Although teratomas may occur in scrotal testicles, they are more common in a retained testis. Other causes of a unilateral scrotal mass include testicular torsion, orchitis, periorchitis, varicocele, testicular hematoma, hematocele and scrotal hernia (8). Cryptorchidism is the most common disorder of sexual development in male horses, arising from abnormal embryological development and descent of the equine fetal testis (8). The retained testis or testes may be abdominal, inguinal or subcutaneous (often termed an ectopic testicle; 3). In one study, 17% of 2- to 3-yr-old colts referred to veterinary hospitals were diagnosed as being cryptorchid (4). Although suspected of being heritable, equine cryptorchidism is likely to be a complex developmental condition sensitive to abnormal numbers of a wide array of genes located on many different chromosomes (8). The testes usually enter the inguinal canal between 270 and 300 d of gestation, and are found within the scrotum between 30 d prior to and 10 d after birth (1). During the first 2 wk after birth, the internal inguinal canal constricts and fibroses and essentially prevents the testes from entering or leaving the scrotum after that time (3). Unilateral testicular retention is 9 times more common than bilateral, with the right and left testicles involved at about equal frequency (8). Retained left testicles are more likely to be located abdominally than inguinally, whereas retained right testicles are more commonly within the inguinal region. This is thought to be due to the slightly larger size of the left testicle making it more likely to resist access to the inguinal canal and therefore to be retained abdominally (8). Cryptorchids may present as intact horses, containing either no testes or one scrotal testis. A more common presentation is an apparent gelding with a history of stallion like
540
Theriogenology
behaviour. These cases may be true bilateral cryptorchids, but often are the result of inappropriate surgical intervention in that only the descended testicle has been removed. Diagnosis in such cases depends on careful examination of the scrotum and it’s contents, deep external palpation of the external inguinal ring and palpation per rectum of the ventral abdomen in the vicinity of the appropriate internal inguinal ring. Transinguinal and transrectal ultrasonography is also useful in locating a cryptorchid testicle since the ultrasonographic appearance of a testicle is characteristic (8). Endccrinological testing is widely used to diagnose cryptorchidism. The most common test (8) is to compare serum testosterone concentrations before and after intravenous administration of 6 to 12,000 IU hCG (Follutein, Solvay Veterinary, Inc., Princeton NJ, USA). A single serum sample may be assayed for estrogen concentration in animals older than 3 yr of age, since horses with testicular tissue produce high levels of estrogens (8). This case raises a number of important issues. First, professional ethics is of concern since it is possible that a veterinarian intervened to make the animals appearance comply with breed association guidelines. Second, the presence of abnormal scrotal contents should have been detected at a prepurchase examination prior to the current owner purchasing the horse. A prepurchase examination of a stallion being considered for show and breeding purposes should include examination of the scrotum and contents by palpation. It is not known whether such an examination was performed. Third, the fact that this horse was capable of propagating a potentially heritable trait is cause for concern. Finally, complications have been reported previously following placement of an implant in a stallion’s scrotum (5). These include infection, development of draining tracts, scrotal inflammation and possibly adverse effects on the contralateral testicle due to scrotal hyperthermia from the local inflammatory response (5). The scrotum in this case showed no evidence of infection. A thick fibrous capsule had developed around the implant, but there appeared to be little effect on the function of the contralateral testis, as determined by subsequent semen analysis. REFERENCES 1. Amann R. Physiology and Endocrinology. In: McKinnon A, Voss J (eds), Equine Reproduction. Philadelphia, Lea and Febiger, 1993; 677-679. 2. Caron J, Barber S, Bailey J. Equine tesicular neoplasia. Comp Cont Ed 1985;7:S53-S59. 3. Genetzky R, Shira M, Schneider E, Easley J. Equine cryptorchidism: Pathogenesis, diagnosis and treatment. Comp Cont Ed 1984;6:S577-S582. 4. Hayes M. Epidemiological features of 5009 cases of equine cryptorchidism . Eq Vet J 1986;18:467-471. 5. Himichs K, Gentile D, Hurtgen J, Richardson D. Complications from a testicular prosthesis in a stallion. JAVMA 1985;186:390-391. 6. Leipold H, DeBowes R, Bennett S, Cox J, Clem M. Cryptorchidism in the horse: genetic implications. Proc AM Mtg AAEP 1986;579-589. 7. Peterson D. Equine testicular tumors. J Eq Vet Sci 1984;4:25-27. 8. Vamer D, Schumacher J, Blanchard T, Johnson L. Diseases of the testes. In: Varner D, Schumacher J, Blanchard T and Johson L (eds), Diseases and Management of Breeding Stallions. Goleta, CA, American Veterinary Publications, 1991; 193-204.