Veazie Veterinary Clinic
1522 State Street, Veazie, ME
(207) 941-8840

Mast Cell Tumors

General Information About Mast Cell Tumors:

A mast cell is a normal part of a pets immune system. It is part of  their allergic response to things. Mast cells are therefore in tissues that interact with the outside environment like skin, lungs,  and intestinal tract. But, they do also circulate in the blood. When abnormal growth of mast cells occurs they can form a tumor. Mast cell tumors are incredibly common in dogs, 1 in 5 skin tumors, according to Veterinary Partners. In cats, older cats seem to be more affected.

Mast cell tumors are graded based on severity from 1 to 3. One is the best to have because it is the least aggressive and easiest to treat.


Diagnosis is made with a fine needle aspirate. We take a small cell sampling with a needle and look at it under the microscope. We can also remove the mass and send it out for histopathology to find out its grade. This will determine the types of additional treatments recommended by the veterinarian.


Surgery is necessary to remove the tumor. Mast cell tumors are highly invasive and very deep. Depending on the grade of the mast cell the veterinarian may or may not recommend chemotherapy. Mast cells respond best to predisone, lomustine and vinblastine.