Mast Cell Tumors

If your cat has been diagnosed with a mast cell tumor (MCT), knowing more about the disease can help you provide them with a better quality of life. MCTs in cats represent 20% of skin tumors, and 15% of splenic tumors, and are the third most common intestinal tumor.

What is a mast cell tumor (MCT)?

Mast cells are part of the body’s immune system. An MCT is an abnormal growth of mast cells, and can be found in a cat’s skin, spleen, or intestines. The tumor contains histamine granules that, when released, can cause gastrointestinal signs, or allergic reactions. An MCT can be “well-differentiated,” which represents between 50% and 90% of all cases in cats, or “poorly-differentiated,” and have the potential to spread to other body organs (i.e., metastasis). 

What are common MCT signs in cats?

Early signs include:

• A skin tumor, possibly pink or red in color
• Itching at the tumor
• Sudden tumor growth or disappearance

Intermediate to advanced signs include: 

• Multiple skin tumors
• Lethargy
• Loss of appetite
• Vomiting or diarrhea
• Distended abdomen
• Collapse

How are MCTs managed in cats?

Complete surgical excision of an MCT is the preferred treatment. Removal of the spleen (i.e., splenectomy) is recommended for splenic tumors. Radiation therapy and/or chemotherapy may be recommended, especially if surgery is not an option. Corticosteroids can lead to a brief remission. Palliative medications to prevent systemic or gastrointestinal effects can be helpful. Discussing a personalized management plan with your veterinarian, and a veterinary oncologist, is important for the best outcome for your cat. 

What is the prognosis for cats with an MCT?

The prognosis depends on successful surgical tumor removal, and whether signs of metastasis are seen. Complete excision of a well-differentiated skin MCT is often curative, but has a 24% local recurrence rate. A splenic MCT has a metastatic rate of up to 22%, with a 12- to 19-month survival time after surgery. Intestinal MCTs have a high metastatic rate, and a poorer prognosis.

Management tips for cats with an MCT 

At-home needs include:

• Easy access to food, water, and litter box, and a comfortable location
• Consistency with prescribed medications
• Close monitoring for tumor recurrence, or systemic disease signs
• Post-surgical care as recommended by your veterinarian

For end-of-life care:

• Try to keep your cat safe and comfortable
• Ensure adequate nutrition and hydration
• Monitor for pain or discomfort
• Evaluate your cat’s quality of life with our scoring tool
• Track progression of their health with our calendar

In a crisis situation:

• Contact your veterinarian immediately if your cat develops swelling or drainage at the surgery site, lethargy, loss of appetite, vomiting, or diarrhea; collapses; or vocalizes in pain. 

Before your cat‘s condition becomes unmanageable, or they begin losing their quality of life, beginning end-of-life care discussions is vital. Learn more about pet hospice, in-home euthanasia, and our teleadvice service, or contact a Lap of Love veterinarian in your area, so you can feel fully prepared for this difficult time.