Rodent Ulcers in Cats A rodent ulcer begins as a yellow or pink
shiny spot that deepens and becomes an open sore. Often, it
begins on either side of center on the upper lip. Less commonly,
it occurs on the lower lip or at the back of the jaw behind one
of the last upper molars. Some cats will also develop an ulcer
on the tongue. It is not itchy and seems to cause no pain. As
the ulcer advances, the lip may be partly eroded by a large,
ulcerated swelling that exposes teeth and gums. This unsightly
condition is unique to the cat. It may be found in cats of any
age, and occurs three times more often in females than males.
The exact cause of rodent ulcer is unknown, and there is
actually no direct connection with rodents. The presence of
eosinophils suggests an allergic reaction, parasite problem, or
immune problem. It is thought to be part of the eosinophilic
granuloma complex. Hypersensitivity is strongly suggested, with
causative agents including insects, environmental substances,
and diet. Flea allergy should