Testicular Tumors in Dogs

Overview of Tumors in Testicle in Dogs

Testicular tumors are common tumors that involve the testicles in intact male animals. The three most common types of testicular tumors are Sertoli cell tumors, interstitial cell tumors and seminoma.

Testicular tumors usually develop in older animals, with 10 years old being the average age. The majority of testicular tumors are benign, but about 15 percent of Sertoli cell tumors are malignant. Five to 10 percent of seminoma tumors are malignant. Interstitial cell tumors are very rarely malignant.

The cause of tumor development is unknown, but dogs that are cryptorchid, that have a testicle that has not descended into the scrotum, are much more likely to develop a tumor. Cryptorchid testicles are generally intra-abdominal (within the abdomen), but may be under the skin in the inguinal area where the hind leg meets the body wall.

Testicular tumors may occur in any breed of dog, but may have an increased incidence of occurrence in German shepherd dogs, boxers, Weimaraners and Shetland sheepdogs.

What to Watch For

Signs of testicular tumors in dogs may include:

Diagnosis of Testicular Tumors in Dogs

Treatment of Testicular Tumors in Dogs

Home Care and Prevention

Watch the incision daily for any sign of swelling or discharge. The scrotal sack may be slightly swollen postoperatively, but the swelling should slowly resolve within a week or two.

If skin sutures are used, they should be removed in 7 to 10 days. If your dog begins to lick the area excessively, an Elizabethan collar designed to prevent licking at incisions may be required. Seek veterinary care if your dog has a fever, or is feeling ill postoperatively.

If your dog had bone marrow hypoplasia, usually due to a Sertoli cell tumor, close monitoring of blood tests will be required.

An excellent preventive measure is to have your dog neutered (castrated) at an early age.

In-depth Information on Testicular Tumors in Dogs

Testicular tumors are the second most common tumors in intact male dogs, the first being skin tumors. The condition usually appears in older dogs but has been seen in dogs as young as three years old. There are three main types of testicular tumors and about a third of dogs that develop a tumor will actually have more than one type present.

Dogs often have tumors in both testicles, even if only a single mass is palpated, so it is important that both testicles be removed when removing a neoplastic or cancerous testicle. Occasionally, testicular tumors may predispose the testicle to twist and cause an acute (sudden) swelling of the scrotum and significant pain. This is testicular torsion. If the testicle were undescended or cryptorchid, the torsion would cause abdominal pain. At other times the neoplastic testicle may cause an obstruction of the lymph drainage in the scrotum, leading to a swollen, but generally not painful scrotal sack.

The largest risk factor for the development of testicular tumors is having a cryptorchid testicle. A cryptorchid testicle is about 14 times more likely to develop a tumor than a scrotal testicle. Sertoli cell and interstitial cell tumors account for nearly 100 percent of tumors in these cryptorchid testicles. In descended scrotal testes, all three tumor types appear in nearly equal percentages.

Occasionally, testicular cancer can lead to a condition known as male feminizing syndrome. This occurs if the tumor causes hormonal changes that result in an increase or relative increase in blood estrogen levels. The most common tumor to cause this is a Sertoli cell tumor, although the other tumors may occasionally be responsible. About 25 percent of Sertoli cell tumors and 70 percent of all cryptorchid testicular tumors cause this syndrome. This can be a very serious illness, as increased estrogen production not only affects a dog’s outward appearance, it can also affect the bone marrow.

The clinical signs associated with the feminizing syndrome include: enlargement of the mammary glands, possibly with the production of milk, symmetrical hair loss, increased skin pigmentation, infertility, decreased libido, a pendulous penile sheath and atrophy of the non-neoplastic testicle. Squamous metaplasia and enlargement of the prostate may also be seen. High levels of estrogen also cause a suppression of the bone marrow (bone marrow hypoplasia), and may lead to significant decreases in the white blood cells, red cells and platelets (blood cells that help in clotting). This may lead to infections, anemia and bleeding problems that may be life-threatening and require emergency treatment.

Other testicular tumors can also produce increased levels of male hormones called androgens. Elevated androgens may predispose animals to the development of prostatic disease and perianal (around the anus) disease. Symptoms of prostatic disease may include hyperplasia (enlargement), cyst formation, or infection. Perianal diseases associated with prostatic neoplasia include perianal adenomas (benign tumors), adenocarcinoma (malignant tumors), and perianal hernias.

The causes of testicular enlargement or swellings include:

In-depth Information on Diagnosis

In-depth Information on Treatment

Most dogs with testicular tumors have no symptoms and feel fine. Often the tumors are found incidentally on a routine physical examination. When found, the recommendation should be castration, unless the dog is a poor anesthetic risk, and the diagnostic evaluation suggests a benign condition.

Based on these findings, it may be more prudent to postpone surgery and observe the tumor for changes. This decision must be carefully discussed with your veterinarian, and the potential problems from not removing the tumor weighed carefully against anesthetic and other risks. If possible the tumor should be removed.

Cryptorchid testicles with tumors have a higher incidence of malignancy, and it is strongly recommended to have them removed. Cryptorchid testicles that are located under skin in the inguinal region are fairly easily removed, however, for cryptorchid tumors located within the abdominal cavity an abdominal exploratory is needed.

Bone marrow stimulating factors may also be used in an attempt to speed the recovery of the bone marrow cells, although its efficacy is uncertain. Specifically, erythropoietin is used to stimulate the red blood cell lines and granulocyte colony-stimulating factor (G-CSF) may be used for the white blood cell lines. Multiple blood transfusions may be needed to sustain an animal before the bone marrow recovers. Signs of bone marrow improvement may take three to six weeks, but not be normal for several months. Unfortunately, most animals with bone marrow involvement do not respond to therapy.

Follow-up and Home Care for Dogs with Testicular Tumors

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not improve rapidly.