Mast Cell Tumors

What are Mast Cell Tumors?
Mast cells are found in the dermal layer of the skin and are involved in the body's response to inflammation and allergens. Sometimes these cells begin to grow out of control. Mast cell tumors are the most common skin tumors in dogs; although less common, they can also appear in other parts of the body.

How does my dog get Mast Cell Tumors?
As with most cancers, the cause is not known. Because mast cell tumors are found more often in certain breeds, a genetic factor is presumed.

How do I know if my dog has Mast Cell Tumors? 
Most owners first notice a mast cell tumor as a lump on the skin. About half are found on the truck, about 40% on the extremities, and about 10% on the head and neck. They may feel soft or hard, and may be reddened.  If you see a suspicious lump, your veterinarian should examine it as soon as possible.  She will probably obtain some cell samples through a needle, which can be examined under a microscope for evidence of cancerous mast cells. This may be followed by a tissue biopsy, which yields the most definitive diagnosis. Radiographs, ultrasound and other imaging tests may be performed to see how widespread the cancer is.

What can I do about Mast Cell Tumors?
Treatment of choice is complete surgical removal. Surgery may have to be repeated if tumor cells are found to extend to the margins of the excision. Subsequent treatment depends on how widespread the cancer is and what stage or aggressiveness the tumor is. Any affected lymph nodes should also be removed, followed by chemotherapy or sometimes radiation therapy. Dogs cope well with chemotherapy, and rarely suffer from the same side effects that humans do. Your dog's individual prognosis will depend on many factors, including where the tumor originated and if it's metastasized. Many dogs develop subsequent tumors that must be removed.

Is there anything I can do to prevent my dog from getting Mast Cell Tumors?
At this time there is no prevention.

Are there certain breeds that get Mast Cell Tumors more often?
All breeds are susceptible, but Bernese Mountain Dogs, Golden Retrievers, Boxers, and Boston Terriers appear to be predisposed.