Testicular Tumors in Dogs

Testicular tumors can be found in many older, intact male dogs.

Testicular cancer need not be a death sentence for your dog, thanks to recent advances in cancer research in the veterinary medical community. The second most common cancer in older, intact male dogs, many canines with testicular tumors recover after treatment to live long, healthy lives. Consulting with your veterinarian on what type of tumors your pet has and how best to treat him ensures that he will receive the best care possible.

Types & Etiology

Your veterinarian may diagnose three types of testicular tumor in your pet, depending on which cells are affected.

Sertoli cell tumors occur in the elongated cells of the tubes located in the your dog's testes that protect, support and give nutrition to the new, unformed sperm cells as the cells mature. These tumors present in only 8 percent of all canine testicular tumors, making them the least common, says Dr. Daniel Degner, a veterinary surgeon on the Vet Surgery Central, Inc. website. Sertoli tumors appear more often in male dogs with a condition called cryptorchidism (one or both testicles are undescended) and tend to metastasize faster than other tumors.

Interstitial cell tumors, also called Leydig cell tumors, develop in the connective tissue cells of the testes that furnish the internal secretions that allow sperm to move freely through the testes and penis. The most common of all testicular neoplasms, according to Dr. Degner, the small, benign Leydig cell tumors present with few symptoms in your dog.

Seminomas appear from the sperm-producing cells of your dog's testicle. Commonly diagnosed in the older male dog, they often occur in undescended testes. Typically benign, they rarely spread, and some of the tumors produce estrogen, resulting in the male dog becoming more feminine.

Symptoms

Clinical signs of testicular tumors include enlargement of the scrotum and/or groin area, a mass in the abdomen, or the signs of feminization that occur when the affected areas begin producing estrogen instead of testosterone. Vets recognize a male dog as being feminized if he has a a sagging, enlarged prepuce (the skin covering the penis); a smaller-than-normal penis; enlarged mammary glands and nipples; and if he attracts the sexual attention of other male dogs, according to Drs. Stephen Withrow and E. Gregory MacEwen in their book "Small Animal Clinical Oncology."

Treatment & Prognosis

Veterinary treatment of testicular cancers typically results in the surgical castration (neutering) of the patient. Because most of these tumors are benign, neutering may be the only medical care your dog needs and is considered curative, say the veterinarians at the Pet Education website. When the cancer has metastasized, vets recommend chemotherapy as a follow-up treatment, and the more guarded prognosis depends upon the location and type of tumor.

Prevention

Surgical castration of young dogs prevents instances of testicular cancer in later life because it removes the cellular tissue where the tumors appear to originate. Dr. Johnny D. Hoskins of DVM360.com advocates neutering stud dogs after their breeding days have passed and castrating all cryptorchid dogs, never using them as breeders because the trait is genetic.

Warning

Dogs with Sertoli cell tumors may suffer the effects of bone marrow suppression that occurs when they become feminized. The excess of produced estrogen causes the male dog's bone marrow to stop producing red blood cells, and many animals develop an anemia that is resistant to treatment. These same animals show a predisposition to internal bleeding and overwhelming bacterial infections that don't respond to therapy, say Drs. Bethany Sabatino and Jagannatha Mysore of the College of Veterinary Medicine, University of Georgia. Animals in this condition often die.

References

• Vet Surgery Central Inc.: Cancer of the Testicles in Dogs
• "Small Animal Clinical Oncology"; Stephen J. Withrow, DVM, and E. Gregory MacEwen, DVM; 2001
• Pet Education: Testicular Tumors in Dogs
• DVM360: Testicular Cancer Remains Easily Preventable Disease
• College of Veterinary Medicine, University of Georgia: Tumors of Dog Testis

Resources

• 29th World Congress of the World Small Animal Veterinary Assoc.: Canine Testicular Tumors