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Testicular Cancer

Issue Description
Testicular tumors are considered one of the most common tumors in older intact (unneutered) male dogs.
Other Names
Testicular Tumors, Canine Testicular Cancer, Testicular Neoplasms


Causes
Testicular tumors are most common in intact (unneutered) older male dogs. However, they can occur in intact males of any age. There does not appear to be any breed predilection for this tumor. The current cause of testicular tumors is unknown. Dogs that have one or both testicles that are not descended (cryptorchid) are 13 times more likely to develop a tumor in the undescended testicle than dogs with normal testicles. Except for the increased risk of these tumors in cryptorchid dogs, no other risk factors are readily apparent.

Symptoms
Sertoli cell tumors show symptoms of swelling of the testicular and scrotal area. If the dog is cryptorchid, the swelling will occur in the inguinal or abdominal area depending on the location of the testicle. Up to 50% of the Sertoli cell tumors will produce estrogen and the dog will suffer symptoms of hyperestrogenism. These include an enlarged prostate gland, enlarged mammary glands and nipples, symmetrical hair loss, anemia, and the tendency to attract other male dogs. Sertoli cell tumors may mestasize to the abdomen, lung, thymus, and brain, however, this occurs in less than 15% of the cases. Seminomas will also appear as swellings of the testicle, scrotum, and inguinal or abdominal area. Seminomas produce estrogen or metastasize in less than 5% of the reported cases. Interstitial cell tumors show very few symptoms and do not produce estrogen or metastasize. They are usually incidental findings and not considered to be much of a problem.

Diagnosis
Diagnosis is based on history, presentation, and pathological identification through a biopsy or microscopic examination of the removed tumor. Dogs suspected of a testicular tumor should also have abdominal and chest x-rays to check for metastasis as well as a chemical panel and a blood count.

Treatment
Treatment usually consists of surgical castration. Because of the success of testicular removal and the low rate of metastasis, castration is often the only treatment needed. Some dogs have been treated successfully with chemotherapy and in dogs that have metastasis, chemotherapy is sometimes recommended.

Prognosis
The prognosis for dogs with treated testicular cancer is usually very good. The low rate of metastasis makes surgical castration very successful and curative in most dogs. Dogs that develop hyperestrogenism from Sertoli cell tumors will often have a regression of symptoms, once the tumor has been removed. In severe hyperestrogenism that results in anemia, some animals may require transfusions and more aggressive treatment. The prognosis for testicular tumors that have metastasized is more guarded and the outcome varies widely depending on location, type, and treatment.

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