If your cat shows up with a fat lip and she hasn’t been in a fistfight lately, she may have a rodent ulcer. Rodent ulcers (like the one shown above) typically appear on the upper lip, usually as a small swelling. Over time, and with frequent licking, the area can enlarge and ulcerate.
Rodent ulcers, also known as eosinophilic ulcers, are the result of eosinophils gone wild. An eosinophil is a type of white blood cell that releases biochemicals in response to an allergy or the presence of parasites. Sometimes, the biochemicals released by the “eos” attack the cat’s own tissue instead of an invading foreign body. The target area of the eos’ action becomes inflamed and sore.
Rodent ulcers can be difficult to resolve. Anti-inflammatory medications may be called for. Recently, some veterinarians have begun using allergy medication with limited success. The patient in these photos was treated with a combination of medications, including an allergy drug, with immediate results. The patient’s ulcer reduced in size and the lip swelling decreased.
Stubborn cases of rodent ulcer may require biopsy (to rule out cancer) and further study, including parasite treatments and food trials.
If you notice a sore or swollen area on your cat’s lips or tongue, have your veterinarian check it out. Early treatment may help prevent permanent disfigurement.
Tip: remove plastic food and water bowls and plastic toys, as they can be irritants to cats sensitive to plastics.