Seminoma in Dogs

Overview of Seminoma in Dogs

A seminoma is a tumor of the testicle that involves the germinal cells that normally produce sperm cells. The majority of seminomas are benign, usually slow growing, and not invasive. Five to ten percent are malignant.

The specific cause of tumor development is unknown, but dogs that are cryptorchid, which means that one testicle has not descended into the scrotum, are ten times more likely to develop a tumor. Cyrptorchid testicles are generally within the abdomen, but may be under the skin in the inguinal area, or the area of the body where the hind leg meets the body wall. Cryptorchid testicles are also much more likely to be malignant.

Breeds at greater risk of cryptorchidism such as Weimaraners and Shetland sheepdogs are more likely to develop a seminoma. Boxers are at increased risk of all testicular tumors regardless of cryptorchidism.

Dogs are more likely to develop a seminoma as they age.

Seminomas rarely may produce elevated androgen (male sex hormone) levels or lead to a male feminization syndrome. Seminomas can also cause a severe bone marrow disorder (bone marrow hypoplasia). This is also an unusual occurrence. Most dogs with seminomas are not ill, and many are simply found during a routine physical examination.

What to Watch For

Signs of seminoma in dogs may include:

Diagnosis of Seminoma in Dogs

Treatment of Seminoma in Dogs

Home Care and Prevention

Watch the incision daily for any sign of swelling or discharge. The scrotal sack may be slightly swollen post-operatively, but this 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 may be required to prevent licking at incisions.

Seek veterinary care if your dog has a fever or is feeling ill post-operatively. If your dog had bone marrow hypoplasia due to the seminoma, 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 Seminoma in Dogs

Usually, seminomas are found as incidental findings on a routine physical exam, or an owner may notice a swelling on the pet’s testicle. Seminomas are often found together with other testicular tumors. They occur in both testicles 10 percent of the time. The majority of the time seminomas cause no clinical problems, but occasionally it may be malignant or cause other serious disease conditions.

Malignant seminomas usually spread to the lymph nodes of the inguinal (groin) or caudal (toward the tail) abdominal areas. Occasionally they may spread to the lungs. Rarely cryptorchid testicles with seminomas may become large enough to cause abdominal distention and pressure on other abdominal organs. Seminomas may also produce excessive estrogen or, more commonly, elevated androgen production. Changes in androgen or estrogen levels seen with testicular tumors have been associated with prostatic disease that includes prostatic hyperplasia, infection, abscesses, squamous metaplasia, and cyst formation. Elevated androgen levels may also cause perianal disease including perianal adenomas, carcinomas, and perianal hernias.

Seminomas have also been associated with a male feminizing syndrome. This is caused by changes in hormonal concentrations that result in an elevated estrogen levels that cause the male dog to take on some female characteristics. This occurs more frequently in animals that have Sertoli cell tumors.

A much more severe and potentially life-threatening condition associated with chronic (long standing) elevated estrogen levels and testicular tumors is estrogen-induced bone marrow hypoplasia. Elevated levels of estrogen have a toxic effect on the bone marrow, and bone marrow hypoplasia may develop where the cells in the bone marrow are damaged and cannot function properly. Since the cells in the bone marrow normally produce red blood cells, white blood cells and platelets that help in clotting, decreases in all three cell lines may be seen (pancytopenia). This may lead to anemia (from the decreased red blood cells), infections (from the decreased white blood cells), and bleeding tendencies (from the decreased platelets).

Sertoli cell tumors are the most common tumor associated with this condition, but seminomas can occasionally be responsible. Other diseases that have similar clinical symptoms as seminomas include:

In-depth Information on Diagnosis

In-depth Information on Treatment

The vast majority of dogs with seminomas have an excellent prognosis. However, since there is a higher incidence of malignancy in cryptorchid tumors, a more aggressive work-up and treatment is required. Some animals may experience acute abdominal pain due to a testicular torsion (associated with a cryptorchid seminoma) and may require rapid intervention. Dogs that have the male feminization syndrome have a good prognosis, as long as there is no evidence of malignancy or bone marrow disease. Animals that have bone marrow hypoplasia due to estrogen toxicity must be treated aggressively, although they tend to do poorly. Specific treatment for seminomas include:

Follow-up Care for Dogs with Seminoma

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