Testicular cancer is considered one of the most common
tumors in older intact (unneutered) male dogs. The overall incidence in dogs is not very high because of the large number of dogs that are castrated. However, in intact male dogs these tumors are considered fairly common. The tumors are usually fairly easy to recognize and diagnose. Treatment consists of
castration and is usually curative.
Which dogs are at risk to develop testicular cancer?
Testicular cancer is most common in intact (unneutered) older male dogs. However, it 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 cancer 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.
Are there different types of testicular cancers?
There are three common types of testicular tumors: Sertoli cell tumors, seminomas, and interstitial cell tumors. While there are differences in the types of tumors, they are often treated similarly and are therefore commonly lumped together as testicular tumors.
What are the symptoms of testicular cancer in dogs?
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 have 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
metastasize to the abdomen, lungs, 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.
How is testicular cancer in dogs diagnosed?
Diagnosis is based on history, physical examination, 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
chemistry panel and a
blood count (CBC).
What is the treatment for testicular tumors in dogs?
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.
What is the prognosis for dogs that develop testicular tumors?
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.
How can testicular cancer be prevented?
Testicular tumors are easily prevented through routine castration of male dogs. Castration in young dogs prevents aggression, roaming, urine marking, and a variety of other unwanted male behaviors. The surgery is safe and relatively inexpensive and in the long run saves the owner money. Dogs that are used for breeding can be castrated when they are no longer used for breeding. Dogs that are cryptorchid should always be castrated and the owner should insist that both testicles be removed. Since cryptorchidism is considered to be an inherited trait, cryptorchid dogs should never be used for breeding. Because the retained testicle is 13 times more likely to develop a tumor, it should always be removed.
