VGO 511: Veterinary Andrology and Reproductive Techniques (1+1)

TESTICULAR NEOPLASMS

Testicular tumors are unusual in most domestic animals except the dog and possibly old bulls.

• Primary testicular tumors are usually of three main types and originate from the interstitial cells, the sertoli cells and the germinal epithelium.
• This may be due to a genetic predisposition in dogs and to the maintenances of intact male dogs until they become senile.
• Large tumors result in testicular degeneration probably due to the compressing effect of the tumor on the adjacent seminiferous tubules.
• The degeneration may also be due to the excess steroids produced by the interstitial, or sertoli cell tumors.

TOP

Bulls

• Testicular tumors are seldom observed except in old animals.
• Interstitial cell tumors of a benign type are occasionally observed in bulls over 7 to 10 years of age.
• These may be multiple and in some cases they are large enough to be palpable as small, round, masses, liver-like in consistency and causing the testes to feel lumpy on palpation.

Stallions

• Testicular tumors have been described only occasionally.
• Rare dermoid cysts or teratomas of the testicle of the horse are often found in cryptorchid testes.

TOP

Rams

• Testicular tumors are rare.

Boars

• Testicular tumors are very unusual.

Cats

• Testicular tumors apparently are rare.

Testicular Tumors in Dogs

• Testicular tumors are observed at any age but most commonly in dogs over five years old.

There was a higher incidence of testicular tumors in dogs than in humans.

• The three principal testicular tumors in dogs are, seminomas, serteoli cell tumors (tubular adenomas), and interstitial cell tumors.

TOP

Seminomas

• They are noted in old dogs, over 7 years of age and arise from the germinal epithelium of the seminiferous tubules.
• These tumors originate in atrophic seminiferous epithelium and that the tumor is intratubular before becoming diffuse.
• These tumors grow slowly for months but may develop rapidly at any time.
• They are rather soft in consistency and hemorrhage or necrosis may be present.
• Affected dogs may exhibit lameness and pain by crouching and hunching.
• In some cases seminomas and interstitial cell tumors are present together in the testis.

TOP

Sertoli cell tumors or tubular adenomas

• They are the least common of the principal tumors of the canine testis.
• This tumor arises from the sertoli or nurse cell of the seminiferous tubules and is usually noted in older dogs.

The tumor is often characterized by marked feminization of the male by the estrogens secreted by the tumor cells.

• The estrogenic substances produced by the tumor and causing feminization of the male were not the usual estrogens found in animals.
• The dog may attract other males.
• The penile sheath is swollen.
• There is a definite loss of hair, especially on the abdomen and lower parts of the body, and a loss of sexual desire.
• Mammary hypertrophy or gynecomastia, and enlargement of the nipples and in some cases development of mammary tumors may occur.
• Atrophy of the testicular tissues and penis develops
• Pigmentation of the abdominal skin and scrotum, and female distribution of body fat are exhibited.
• The prostate may undergo marked enlargement due to squamous metaplasis and cysts; or it may become markedly involuted due to atrophy of the epithelial elements and collapse of the acini.
• These tumors are rather large in size, firm, nodular, and fibrous on palpation.
• On cross section, sertoli cell tumors are pale yellow or grey in color and may contain necrotic, cystic, or hemorrhagic foci.
• If no metastases have occurred recovery from the above dramatic symptoms takes place promptly after the affected testis is removed.

TOP

Intestitial cell tumors or adenomas, or Leydig-cell tumors

They are the most common tumors in old dogs.

• Although they are present in many old dogs, they are of little clinical significance.
• Most of them are found only at autopsy.
• They are often overlooked because of their small size; 1 mm to 2 cm is their usual size.
• Nodular hyperplasia of the interstitial cell is seen commonly in older dogs with senile testicular atrophy.
• Nodular hyperplasia is probably a preneoplastic change but the division between nodular hyperplasia and interstitial cell tumor is arbitrary.
• These tumors probably produce androgens because the prostate in affected dogs is normal or hypertrophied.
• The tumors consist of single or multiple well-circumscribed nodules, brownish-orange in color and soft in consistency.
• Large tumors may occasionally by palpated in the testes of old dogs.
• Canine tumors should be carefully differentiated from orchitis or epididymitis, traumatic swellings or hydrocele
• The hydrocele condition may be either congenital or secondary to orchitis.
• Canine perianal gland tumors are probably androgen dependent tumors that can be arrested by castration; about 85 per cent occur in older male dogs with a definite breed incidence in Cocker Spaniels.

TOP