Cryptorchidism
Cryptorchidism is a developmental defect in which complete descent of one or both testes into the scrotum does not occur.
The incidence of cryptorchidism has been reported to be 1% to 15% of adult dogs.11 Normally, the testes should descend to the scrotum by 10 to 14 days after birth with both testicles completely within the
scrotum by 8 weeks of age. However, some authors think that cryptorchidism cannot be diagnosed until dogs are 6 months of
age.12 About 75% of affected dogs are unilaterally cryptorchid, with the right testicle being retained almost twice as often as
the left.11 The cryptorchid testis is smaller than the scrotal testis because of the absence of spermatogonia. However, Sertoli and
Leydig cells remain, and androgen synthesis is unimpaired11; such was the case with the dog in this report. A retrospective study identified 14 breeds with a significantly higher risk
of cryptorchidism and eight breeds with a significantly lower risk of cryptorchidism; German shepherds were on neither of
these lists.13
Dogs with cryptorchid testes are reported to have an increased risk of developing testicular neoplasia.11,12,14 Dogs with abdominal testes tend to develop Sertoli cell tumors as a result of the abdominal temperature causing loss of
all tubule cells except the Sertoli cells. Conversely, dogs with inguinal testes tend to develop seminomas as a result of
transitional inguinal canal temperature, which appears to stimulate neoplastic growth of the spermatogenic cell line. Because
temperature does not affect interstitial cells, the incidence of interstitial cell tumors (as seen in this dog) is not thought
to be related to cryptorchidism.11 The interstitial cell tumor found in this dog was considered clinically insignificant, as these tumors are hormonally silent
and almost always benign.11 Also, the absence of intra-abdominal lymphadenopathy on ultrasonographic examination and surgical exploration of this dog's
abdomen lessened our concern of tumor metastasis. Sertoli cell tumors account for about 60% and seminomas for 40% of tumors
in cryptorchid testes.14
Cryptorchidism is diagnosed by careful inspection and palpation. Abdominal testicles are difficult to identify by palpation
unless diseased and swollen. In the dog in this report, scrotal palpation was normal, and firm medial pressure in the prescrotal
subcutaneous tissues while the dog was in dorsal recumbency was required to palpate this testicle. It is postulated that the
dog was effectively vasectomized at the time of its original abdominal exploration, complicating proper identification and
removal of the remaining testicle at the time of laparoscopic exploration; this finding was supported by gross and histopathologic
examination results postcastration.
Treatment of affected dogs is typically limited to castration, and the breeding of affected individuals is discouraged because
of the hereditary nature of this disease. Gonadotropins (HCG, gonadotropin-releasing hormone) and androgens (testosterone)
have been used with mixed results to treat unilateral and bilateral cryptorchidism.11 Surgical placement of the retained testes into the scrotum (orchiopexy) is considered unethical in veterinary medicine as
it allows the possibility of mating (thus, perpetuating the trait) and does not remove the possible development of undesirable
sequelae such as testicular neoplasia or torsion.
Although not done by this dog's original veterinarian, histopathologic examination of all intra-abdominal testicles removed
surgically or with a laparoscope is recommended15 to evaluate for any testicular neoplasia and to confirm removal of testicular tissue.
John K. Sessions, DVM
Jeanne A. Barsanti, DVM, MS, DACVIM
Department of Small Animal Medicine and Surgery
College of Veterinary Medicine
University of Georgia
Athens, GA 30602
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