Q: My cat has developed a reddish-brown sore on her upper lip. It doesn’t seem to bother her, but it looks awful. And while I thought it would go away on its own, it hasn’t. What should I do?
Patsy Celadon
Birmingham, Alabama
Dear Ms. Celadon,
A: It sounds like your cat has a rodent ulcer, which has nothing to do with rodents. It’s simply a holdover from when it was believed that such ulcerations came from the bite of a rat or mouse. The medical term is eosinophilic ulcer.
Generally, the cause remains unknown, but possible culprits include everything from bacterial infections to flea or food allergies, parasitic infestation, ringworm infection, traumatic damage, and mosquito bite hypersensitivity. Rodent ulcers are observed three times as often in female as in male cats.
Oftentimes, they do go away on their own. But if not, your cat’s veterinarian can prescribe medicine in the form of an anti-inflammatory drug such as prednisone.
Note that some cats develop lip ulcers repeatedly throughout their lives and therefore require repeated courses of treatment. But more often, a cat will simply outgrow the propensity to develop rodent ulcers as she matures. And many develop no
more than one. They’re most commonly found in cats under the age of 6 or 7.
