Leiomyoma in Cats

Leiomyoma in cats tend to be small and localized and are not harmful unless their location impacts organ or system functioning, for example they can block the digestive tract. They tend to occur in older cats rather than younger animals.

Leiomyomas are non-cancerous, non-spreading, benign tumors of smooth muscle tissue. Smooth muscle tissue is the type found around hollow internal organs such as in the gastrointestinal tract, reproductive organs (uterus) and genital tract. Tumors can also occur in the liver, spleen, and in subcutaneous tissue. Gastric leiomyoma are not common but they do occur more frequently in cats than in other species. Uterine leiomyoma (fibroids) are rare in cats.

The symptoms of leiomyoma depend on the tumor's location and what effect it is having on the body's normal functioning. Often there are no symptoms and the tumor is found incidentally while investigating another condition.

When gastrointestinal leiomyoma is affecting normal digestive system functioning, symptoms may include:

• Vomiting
• Loss of appetite
• Loss of weight 
• Gas (flatulence)
• Distended abdomen
• Feeling of incomplete bowel movement if in large intestine (bowel)
• Blood in stool (blockage of large intestine)
• Protrusion of rectum (blockage of large intestine)
• Hypoglycemia - low blood sugar
• Palpable mass in abdomen
• Mass under the skin (subcutaneous)
• Lethargy
• Pain where blockage occurs

Symptoms of leiomyoma in genital tract may include:

• Protrusion of vulva
• Vaginal discharge
• Bleeding

The cause of leiomyoma is not known. There may be some relation to the hormones estrogen and progesterone as uterine leiomyoma have more receptors for these hormones. A genetic component has also been suggested, but this is not well understood. Leiomyoma may be more common in obese animals, but further evidence is needed to verify the relationship between obesity and leiomyoma.

Your veterinarian will perform a full physical exam including blood and urinalysis tests to rule out disorders such as parasites, pancreatitis, ingestion of foreign objects,cancer, or inflammatory bowel disease as a cause for any symptoms that may be presenting. Often leiomyoma is found incidental to treatment for another disorder, as there may be no symptoms. 

If a tumor is found your veterinarian will perform tests to determine if it is cancerous or leiomyoma which are nonspreading, benign tumors. Blood test results will help with this diagnosis, but in some cases, an endoscope with a camera that can take a sample for a biopsy may be employed. 

Digital imaging such as x-ray or ultrasound may also be used to locate the tumor and determine if there is an obstruction to the digestive system or other impairment to normal body function.

Barium may be administered orally, and x-rays taken to monitor the progression of the barium through the digestive system, which will real if any blockages exist. Also, an ultrasound may be helpful in determining location and impact of the tumor.

Your veterinarian will hospitalize your cat if it is in distress and administer supportive care such as intravenous fluid for dehydration.

The usual treatment for leiomyoma is surgical removal. If leiomyoma is in the uterus, spay is usually the simplest solution. Because leiomyomas are localized and enclosed tumors, surgery is usually straightforward and successfully resolves the problem. This can vary, however, depending on the location, size, and the effect the tumor has had on organ functioning. Generally, prognosis is good and there is no spread or relapse expected. 

In cases of gastrointestinal leiomyoma, a modified diet may be recommended to reduce stress on the digestive system and promote healing. Treatment for conditions such as hypoglycemia or any other conditions or symptoms resulting from the leiomyoma may also be necessary.

Recovery is straightforward and involves appropriate postoperative care, which usually includes rest and a low stress environment, free from hazards. A modified diet may be continued and any further concerns addressed with your veterinarian. A full recovery can be expected.