Testicular cancer is a recognized and easily diagnosed disease. It is the second most common type of cancer in older dogs. However, it can occur in healthy male dogs of any age. Three types of tumors are grouped under the umbrella of testicular cancer: interstitial, Sertoli and seminoma. The prognosis is a positive one for most dogs with testicular cancer as long as there are no metastases. This cancer can be prevented by castration.
interstitial tumors
Interstitial tumors are usually benign and do not cause symptoms associated with other types of cancer. These tumors are usually round and less than an inch in diameter. Do not consider it a problem. Interstitial tumors are also called Leydig cell tumors. Interstitial tumors occur more often when the testicle is retained.
Seminomas
Seminomas will cause the testicles, scrotum, groin or abdominal regions to become swollen. It usually only appears in one testicle of the partner and is benign in up to 85 percent of cases. Malignant hereditary tumors may spread to other organs. These tumors are usually under an inch in diameter. They are the second most common type of testicular cancer in dogs.
Sertoli tumors
Like carcinoid tumors, Sertoli tumors can cause swelling of the testicle or scrotum or, if the testicle is retained, in the abdominal or groin areas. In contrast to carcinomas, Sertoli tumors are malignant in 14% of cases. Even half of these tumors will cause feminization, because they produce excessive amounts of estrogen. Malignant Sertoli tumors metastasize to nearby lymph nodes, as well as to the abdomen, brain, lungs, and thymus.
Symptoms of testicular cancer
Cancer testicles are often larger than normal testicles and can be of different sizes. When swollen, the swollen tissue can be soft or firm. The dog’s scrotum may also be swollen. Intact males used as stud dogs may be infertile. Some tumors cause feminization syndrome, due to increased estrogen production. This syndrome can cause enlarged mammary glands, a retracted penis and squatting to urinate.
Diagnosis and treatment of testicular cancer
Physical examinations, including testicular palpation, are essential for the diagnosis of testicular cancer. A biopsy of the tumor can determine whether it is benign or malignant. Additional diagnostic tests include a complete blood count and a veterinary chemistry panel. X-rays of the chest and abdomen should also be taken to determine if metastases are present.
Most dogs are successfully treated by neutering. Both testicles are generally removed, even when only one testicle is affected. Chemotherapy is rarely used, due to the low rate of metastasis in canine testicular cancer. Feminization is usually reversed without further treatment after castration. Dogs with bone marrow involvement will be prescribed additional treatment to cure it.
Prevent testicular cancer
Neutering a male dog is the best form of prevention. Canine retained testicles – dogs with only one testicle descended – must be removed as many of their retained testicles become cancerous. Dogs that have retained testicles should not be bred, as cryptorchidism is often hereditary. Certain breeds of dogs are more prone to testicular cancer, including German shepherds, Weimaraners, Shetland sheepdogs and boxers, so special care must be taken with those breeds.
