Dear Doctor: An Unsightly Sore on the Cat’s Upper Lip


Q. My cat has developed an angry-looking, reddish-brown sore on her upper lip. I thought it was just a wart and would go away on its own, but after several weeks, it’s still there. Should I be concerned?

Maisie Spencer
Troy, New York

A. Dear Ms. Spencer,

It sounds like your pet may have a rodent ulcer — a misnomer that comes from the old, mistaken tale that such sores come from mouse or rat bites. In actuality, it’s a form of a condition known medically as eosinophilic granuloma complex, or EGC. In most cases, the cause is unknown, but possibilities include bacterial infection, flea or food allergies, parasitic infestation, and mosquito bite hypersensitivity.

A rodent ulcer usually will not cause any pain and may disappear on its own within a few months. But if it persists, it may prove uncomfortable and interfere with a cat’s eating. Fortunately, anti-inflammatory medication such
as prednisone will usually take
care of it.

Some cats develop rodent ulcers throughout their lives and may need periodic prednisone treatment. Others outgrow the tendency to form them — they tend to occur in cats under the age of 6 or 7.


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