Overview of Canine Ovarian Tumors

Ovarian tumors are cancerous growths associated with the ovaries, which are the female sex glands where eggs are formed. It is unclear what contributes to the cause of ovarian tumors, except the presence of ovaries in an intact female dog. There are many different types of ovarian tumors, with carcinomas being the most common.

Ovarian tumors are rare in dogs, which more likely reflects neutering practices than resistance to tumor formation. The majority of cases are seen in older dogs, although teratomas are seen in younger dogs. Boston terriers, German shepherds and poodles have a higher incidence of tumors.

What to Watch For

Signs of ovarian tumors in dogs may include: 

Changes in the patient’s estrus (heat) cycle

Infected uterus

Enlarged breasts

Hair loss

Low blood cell counts

Masculinization (male behavior)

Ascites (fluid in the abdominal cavity)

Abdominal enlargement

Lethargy

Fever

Loss of appetite

Difficulty breathing associated with fluid in the chest cavity secondary to metastasis (spread of cancer)

Diagnosis of Ovarian Tumors in Dogs

Baseline tests, to include a complete blood count (CBC), biochemical profile, and urinalysis are recommended, although they are usually within normal limits.

Careful abdominal palpation is often helpful, as some ovarian tumors can be felt by hand.

Abdominal radiographs (X-rays) may reveal a mass in the area of the ovary, rule out other masses, or reveal fluid sometimes seen with ovarian tumors.

Thoracic radiographs are an important part of the work up as metastasis to the chest cavity is not uncommon in these patients.

Abdominal ultrasound may be more sensitive in identifying ovarian tumors.

Cytology (evaluation of cells) in abdominal or thoracic fluid (if present) may confirm cancer.

Biopsy and microscopic evaluation are necessary for a definitive diagnosis.

Treatment of Ovarian Tumors in Dogs

Surgical removal (ovariohysterectomy) is the treatment of choice in those dogs who do not appear to have metastatic disease.

Concurrent chemotherapy may be of benefit.

Home Care and Prevention

It is very important to follow the instructions given to you by your veterinarian. Follow up with abdominal and thoracic radiographs every several months to monitor for recurrence and metastasis is indicated.

Although some dogs do well, the prognosis with ovarian tumors remains guarded.

The best way to prevent ovarian tumors is to remove the ovaries. Have your dog spayed early in life.