What IS a Mast Cell Tumor?

So, what the hell is a mast cell tumor?

Mast cells are found in pretty much all the tissues in the body, especially the skin, lungs, and gastro-intestinal tract.  They are an integral part of the body's immune system and play a role in dealing with inflammation and allergic response.  Mast cells contain a pretty potent brew of compounds that, under normal circumstances are important for healthy biologic function.  Histamine, heparin, and prostaglandin, in just the right quantities and at the correct time, all have a proper role in the body's normal processes.  When mast cells proliferate without regulation, resulting in a tumor, these same elements amass in quantities that can have a devastating and deadly effect on the body.  When mast cells release these compounds, it's called "degranulation".  Dogs experiencing degranulation may go into shock (from the histamine) or excessive bleeding (from the heparin).  Mast cells in the lining of the stomach also increase the release of digestive acids that can cause ulceration, esophagitis, or reflux.  If you have a dog with mastocytoma, I am betting you've already googled the details.  If you haven't, the article on the National Canine Cancer Foundation's website it a very good place to start.