Uterine Tumors in Cats

These tumors, whether cancerous or not, can cause other health problems throughout the body. If the tumors have grown large enough, they may begin to compress vital organs in the abdomen such as the stomach, intestines or bladder. The abdomen may appear visibly larger. Benign uterine tumors are often paired with an infection of the uterus called pyometra. Some uterine growths may actually be cysts that can disappear spontaneously. Veterinary assessment is required for the presence of any uterine tumor.

The uterus is a muscular organ found in female cats. Various internal issues can cause growths to form inside the uterus, in the uterine walls, or outside the uterus. The cat must be intact (not spayed) to contain a uterus. In cats, most of these growths are benign (non-cancerous) tumors. Rarely, malignant (cancerous) tumors may develop. Common benign growths include fibroids, leiomyomas, and fibromas. Malignant growths are generally one of two types: adenocarcinoma or leiomyosarcoma.

In the beginning stages of tumor growth, often no signs are present. In later stages, some cats begin to experience pain, where others still do not. Pyometra symptoms may be the first indication of other uterine problems. All signs to watch for include:

• Vaginal discharge 
• Excessive genital licking
• Dysuria (difficult urination)
• Hematuria (blood in the urine)
• Polyuria (frequent urination)
• Polydipsia (increased thirst)
• Anorexia
• Weight loss
• Vomiting
• Constipation
• Abdominal distention
• Lethargy

Malignant tumors are often caused by a combination of simultaneously occurring circumstances. Benign tumors may be caused by many different underlying conditions. Sex hormones produced by the ovaries seem to have an effect on both benign and malignant uterine tumors. All possible causes are listed below.

• Congenital abnormalities
• Pyometra syndrome
• Trauma or injury
• Hormonal issues
• Improper autoimmune response
• Chemical exposure
• Pregnancy

Be prepared to provide your cat's full medical history to your veterinarian. This can help identify health issues that can lead to uterine tumors. The vet will then perform a complete physical examination of the cat, palpating the abdomen to feel for large masses. Full blood work will be needed, including a complete blood count to check for heightened levels of white blood cells and a biochemical profile to assess liver and kidney function. Urinalysis can also contribute a more detailed review of kidney health.

X-rays or ultrasounds of the abdomen and chest may be needed to confirm and locate any tumors present. The chest is monitored as it is often the first area for uterine cancer to spread to. Uterine tumors must be differentiated from tumors of the vagina, infections, and tumors of the other abdominal organs. A biopsy of the masses may be needed to determine whether the growth is cancerous or not. Often, instead of a biopsy, the whole uterus may be sent for a histopathological examination once it is removed.

A surgical procedure is necessary regardless of whether the tumors are cancerous or not. Secondary conditions, such as pyometra, may also need treatment.

Ovariohysterectomy 

The full removal of the uterus and ovaries is the best way to address uterine tumors. This can be an effective way to manage cancer if it has not yet metastasized to other organs. The ovaries must be removed along with the uterus, as they secrete hormones that often exacerbate tumor growth. General anesthesia is required for this procedure.

Chemotherapy 

If the tumors were found to be malignant, a course of chemotherapy may be recommended along with an ovariohysterectomy to rid cancer on a microscopic level. This may require long-term administration of immunosuppressive medications. 

Antibiotics 

If pyometra has also been diagnosed, a bacteria-specific antibiotic will be prescribed to remove any infection left in the body. Post-surgery, general antibiotics may be prescribed to prevent infection from developing.

The cat will need to be closely monitored while healing from surgery to ensure that the incision is kept clean and dry. Watch for any signs of infection including swelling or blood seepage. Verify that your cat is eliminating normally. Lab results from the removed uterus will reveal if cancer is present, and if so what type it is. Follow-up appointments with the veterinarian will be needed to see if chemotherapy is reducing the amount of cancer cells in the body. If non-location specific symptoms start to recur, the cancer may have metastasized somewhere else in the body.

If the tumors are confirmed as benign, the issue should be resolved upon recovery of the ovariohysterectomy. A special diet may be prescribed if any uterine infection has spread to the kidneys or liver. Giving a cat appropriate supplements can help to strengthen the immune system and prevent these issues from developing. Spaying adult female cats that are not used for breeding purposes will also eliminate the risk of uterine tumor issues.