mast cell tumour

Mast cells are normal immune cells that live in the skin and many organs (especially the spleen, liver, and intestines). They’re loaded with granules containing histamine and other chemicals that help with allergic responses and healing.

In mast cell tumours (MCTs), some of these cells become cancerous and multiply in a lump (or sometimes many lumps). When these tumour cells are disturbed, they can “degranulate,” spilling histamine and related chemicals into nearby tissues and the bloodstream.

That’s why MCTs can shrink and swell, get red and itchy, and occasionally trigger vomiting, stomach ulcers, or—rarely—whole-body reactions.

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How common are they?

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Dogs: MCTs are the most common malignant skin tumour in dogs, making up roughly 11– 21% of canine skin cancers.

Certain breeds (Boxers, Boston Terriers, Bulldogs, Pugs, Labradors, Golden Retrievers) are over-represented.

Cats: MCTs are a top skin cancer in cats and are also common in the spleen and intestines.