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:

• Soft or firm swellings in one or both testicles
• Single enlarged testicle or asymmetric testicles
• Generalized scrotal enlargement
• Infertility in the breeding stud dog

Diagnosis of Testicular Tumors in Dogs

• A good physical examination including palpation (feeling) of the testicles
• Complete blood count (CBC)
• Platelet count
• Biochemical profile
• Urinalysis with or without culture and sensitivity
• Thoracic (chest) and abdominal radiographs (x-rays)
• Abdominal and or scrotal ultrasound
• Fine needle aspiration or biopsy
• Histopathology (microscopic analysis of tissue) of removed testicle

Treatment of Testicular Tumors in Dogs

• Surgical removal of both testicles
• Chemotherapy if the tumor has metastasized
• Radiation therapy if the tumor has metastasized
• Supportive care if associated disease conditions are present

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:

• Orchitis and epididymitis are inflammations of the testicle and epididymis, which is the tube-like structure along-side the testicle. They are usually caused by a bacterial infection. The condition is generally painful, and dogs tend to feel ill. Affected dogs may also have a fever. If the infection is severe, the swelling in the testicle may begin to spread up the scrotum and into the inguinal area. Epididymitis may sometimes be caused by Brucella infection.
• Testicular torsion is a twisting of the testicle where blood supply and or lymphatic drainage is compromised. The testicle is usually symmetrically enlarged and painful. The condition is often associated with testicular neoplasia. Testicular torsions occur with greater frequency in abdominal cryptorchid testes.
• A spermatocele also called a sperm granuloma may occur due to a cyst-like dilation of the epididymis. Sperm may become trapped inside the dilation, and an inflammatory response may occur. This response may produce a small swelling in the epididymis. It is a benign condition, but may result in infertility.
• An inguinoscrotal hernia occurs when abdominal contents pass into the scrotal sack. Most commonly, it is fatty tissue or a loop of bowel that enter through the inguinal canal. It is not a common condition.

In-depth Information on Diagnosis

• Complete physical examination. All intact male dogs should have their testicles palpated as part of their routine physical exam. Most testicular tumors are found incidentally during the exam, since most dogs do not display any symptoms of illness.
• The complete blood count evaluates the red and white blood cells. Low red blood cell counts indicate anemia, and elevations in the white blood cell count may indicate infection. The test is especially useful when an estrogen secreting tumor is suspected. Low red cell and white cell counts (leukopenia) would indicate a serious condition. The reticulocytes, which are young, recently released red cells from the bone marrow, might be counted, to determine whether the bone marrow was responding to the anemia by producing new red cells. The reticulocyte count would be low (non-regenerative) if the anemia was due to estrogen toxicity.
• Just as the red and white cell lines are decreased with bone marrow hypoplasia, the platelets 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.
• The biochemical profile evaluates for liver or kidney disease, diabetes, and changes in electrolytes. Since most dogs are older if they have a Sertoli cell tumor, 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 preoperative blood work.
• 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 fully assess kidney function.
• Even though metastatic disease is uncommon with most testicular tumors, thoracic radiographs are useful in evaluating the lungs for any potential tumor spread. In older animals, it is also a good preoperative screening test to evaluate for evidence of heart disease or other lung conditions. In the cryptorchid dog, abdominal radiographs are taken, as many larger testicular 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 sublumbar (under the lumbar vertebrae) lymph nodes 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 testicular tumor. 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 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 histopathology or microscopic examination of tissue. Biopsy usually provides more accurate information since a larger amount of tissue (usually the entire testicle) can be evaluated. Cryptorchid testicles are biopsied using ultrasound as a guide or at surgery. Many times the biopsy is combined with the full removal of the entire tumor (excisional biopsy). Based on the previous diagnostics, it is not always needed to biopsy a tumor prior to its removal.

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.

• Orchiectomy (castration). The treatment of choice for any testicular tumor is the surgical removal of both testes. Since the majority of testicular tumors are benign, the surgery is usually curative. Both testes are removed due to the high incidence of tumors involving both testicles. When removing abdominal cryptorchid tumors a complete evaluation of all internal organs should be done to check for evidence of metastatic disease.
• Chemotherapy is a treatment option for Sertoli cell tumors that have spread. Some of the drugs that have been used in treatment include: cisplatin, cyclophosphamide, vinblastine and methotrexate. Unfortunately, the prognosis of metastatic Sertoli cell tumor is grave regardless of therapy. Chemotherapy may decrease the tumor volume, and improve an animal’s quality of life for a few months but it is not a cure.
• Radiation therapy for metastatic seminomas is an option that may be available at certain referral institutions. Although metastatic seminomas are extremely rare, the tumors are relatively responsive to radiation therapy.
• 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 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.

• Administer all medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.
• The incision and scrotum should be checked daily for any signs of swelling or discharge. Routine castrations usually do not require antibiotics, but if there is a significant amount of discharge from the incision or swelling, infection may be present and antibiotics advised. Occasionally blood may ooze into the scrotum postoperatively causing a scrotal hematoma (blood clot). Scrotal hematomas may become quite large and can be painful, but they usually resolve on their own.
• If bone marrow disease was present, a CBC and platelet count should be followed closely looking for improvement in the red and white blood cell counts as well as platelets. Prophylactic antibiotics may need to be given long term, while the white blood cell counts are depressed, in an attempt to decrease the incidence of infection.