Dr. Douglas Brum
Complete physical examination. All intact male dogs should have their testicles palpated as part of their routine physical exam. Most seminomas are found incidentally during the exam, since most dogs do not display any symptoms of illness. On the other hand, dogs with the feminization syndrome have typical physical exam changes that suggest a hormonal cause of the problem.
CBC. The CBC evaluates the red and white blood cells. The test is especially useful if a seminoma is causing bone marrow hypoplasia. Decreased red cell counts (anemia) and low white cell counts can be expected in this serious condition. The reticulocytes – young, recently released red cells from the bone marrow – might be counted to determine whether the bone marrow was responding to the anemia appropriately by producing new young red cells. The reticulocyte count is low (non-regenerative) if the anemia was due to estrogen toxicity. The only way to confirm the diagnosis of bone marrow hypoplasia is through a bone marrow aspirate and microscopic evaluation of the cell types.
Platelet count. Just as the red and white cell lines are decreased with bone marrow hypoplasia, the platelets, which are also produced in the bone marrow, may also be decreased. This test is especially important to run if any excessive bleeding or bruising is noted.
Biochemical profile. The biochemical profile evaluates for liver or kidney disease, diabetes, and changes in electrolytes. Since most dogs with seminomas are older, it is a valuable screening test for other concurrent diseases. If the tumor is malignant, and has metastasized (spread), elevations in liver enzymes might be noted. Additionally, all animals that are to undergo a surgical procedure should have a biochemical profile done as part of their pre-operative blood work.
Urinalysis. If the testicular swelling is caused by an infection, a urinalysis with a culture and sensitivity might show bacteria and an increased white blood cell count. A urinalysis is also needed to assess kidney function.
Even though seminomas are rarely malignant, chest X-rays are recommended to determine if the tumor has spread to the lungs. In older animals it is also a good pre-operative screening test to evaluate for evidence of cardiac disease or other pulmonary conditions. In the cryptorchid dog, abdominal X-rays are taken, as many larger tumors may be easily visualized. Abdominal X-rays are also useful in evaluating the size and shape of other abdominal organs. Occasionally, with metastatic disease, the lymph nodes under the lumbar vertebrae may be enlarged and visible radiographically.
An abdominal ultrasound is useful to better identify a mass within the abdomen as can be seen with a cryptorchid seminoma. The rest of the abdomen can also be checked for signs of tumor spread and other organ involvement. In non-cryptorchid dogs, generalized scrotal swelling is sometimes present. This may prevent accurate identification of a specific mass. A scrotal ultrasound is an excellent test to determine if a tumor is present in a swollen scrotum.
With the aid of ultrasound, an abdominal mass can be aspirated by fine needle. The collected cells are then examined microscopically (cytology). A fine needle aspirate is generally a safe and effective method of tissue evaluation, but it may not be diagnostic, since only a small amount of cells are collected. Intra-scrotal testicular masses generally do not require ultrasound for aspiration.
A biopsy provides a better sample as a core of tissue is obtained for microscopic examination (histopathology). More accurate information is usually obtained since a larger amount of tissue can be evaluated. Cryptorchid testicles have biopsies using ultrasound as a guide or at surgery. Most times the biopsy is combined with the full removal of the entire tumor, which is called an excisional biopsy. Based on the previous diagnostics, it is not always needed to biopsy a tumor prior to its removal.
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:
Orchiectomy (castration). The treatment of choice for seminomas, either scrotal or cryptorchid is the surgical removal of the affected testicle. Both testes are removed due to the high incidence of tumors involving both testicles. Cryptorchid testicles often require major abdominal surgery, and a more prolonged hospital stay. A complete evaluation of all internal organs should be done at surgery to check for evidence of metastatic disease. The vast majority of dogs with seminomas have no evidence of tumor spread at the time of diagnosis and orchiectomy is curative.
Chemotherapy for metastatic seminomas might be considered, although there is limited experience in its use in dogs.
Radiation therapy is probably the best treatment option for metastatic disease, but again experience is limited. Seminomas in people are very sensitive to radiation therapy, and in the limited number of cases in dogs, radiation therapy also seems to be an effective treatment option. Radiation therapy usually requires referral to a specialty practice or academic institution.
Dogs that have bone marrow hypoplasia may be quite ill and require significant care. Therapy for anemia, infection, and potential bleeding problems needs to be addressed. Intravenous fluids, broad-spectrum antibiotics, and blood or platelet transfusions may be needed to stabilize the patient prior to the surgical removal of the tumor. 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 (EPO) 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 3 to 6 weeks, but may not be normal for several months. Unfortunately, most animals with bone marrow involvement do not respond to therapy.