Dear Mary Hellen,

I am glad Sonny is still eating, but the change in his behavior is important. “Rodent ulcers,” more accurately called indolent or eosinophilic ulcers, are part of the feline eosinophilic granuloma complex and are commonly associated with hypersensitivity reactions. They are often not very painful themselves, so if Sonny is now lying around and appears uncomfortable, I would not assume that the ulcer alone explains everything.

Because Sonny is older and this problem has changed after years of treatment, I would recommend a veterinary examination soon, ideally including a careful oral examination under sedation or anesthesia if needed. The veterinarian should make sure this is truly an eosinophilic ulcer rather than another painful oral condition, such as dental disease, feline chronic gingivostomatitis, tooth resorption, an oral tumor, or secondary infection.

Persistent or unusual ulcers, particularly those that are focal or do not respond as expected, may warrant a biopsy because several different diseases can look quite similar from the outside.

The previous injections may have been corticosteroids, which commonly make eosinophilic lesions improve, but repeated or long-term steroid treatment in a senior cat deserves particular care because the risks and benefits can change as a cat ages. It is also worth investigating potential underlying triggers, especially strict flea control and, when appropriate, a properly conducted dietary elimination trial.

Think of the ulcer as the smoke rather than the fire; treating the visible lesion can help, but identifying what is driving the inflammation is what may reduce recurrence.

For now, I would prioritize getting Sonny’s mouth and overall health assessed rather than relying on the supplement alone. His continued appetite is encouraging, but cats can be remarkably stoic about oral pain, and becoming unusually quiet or withdrawn can be an important indication that they are suffering. A senior-cat examination with oral evaluation, appropriate bloodwork, and a discussion of whether dental radiographs or biopsy are warranted would be a sensible next step.

Kind regards,

– Dr. Paola