Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

540 •DOG OWNER’S HOME VETERINARY HANDBOOK
Reproductive Tract Tumors
TUMORS OF THE TESTICLES
Testicular tumors are common in male dogs. Most affected dogs are over 6
years of age, with a median age of 10. The majority of tumors occur in undescended
testicles—located in the inguinal canal or abdominal cavity. In fact,
tumors develop in up to 50 percent of undescended testicles. A swelling or
firm mass in the inguinal canal in a dog with an undescended testicle is characteristic
of a testicular tumor (although the mass may simply be the undescended
testicle).
Tumors in descended testicles are less common. The affected testicle is
often larger and firmer than its neighbor and has an irregular, nodular surface.
At times the testicle is normal size but feels hard.
The three common testicular tumors in dogs are Sertoli cell tumors, interstitial
(Leydig) cell tumor, and seminomas. A small percentage of Sertoli cell
tumors and seminomas are malignant.
Some Sertoli cell tumors produce estrogen, which can result in feminization
of the male with enlargement of the mammary glands, a pendulous foreskin,
and bilateral symmetric hair loss. A serious complication of high
estrogen levels is bone marrow suppression.
Ultrasonography is particularly useful in locating undescended testicles and
determining whether a scrotal mass is a tumor, abscess, testicular torsion, or
This dog has a tumor of
the right testicle, causing
asymmetric scrotal
enlargement.