Glossary

Stomatitis

A painful, long-lasting inflammation of a cat's gums and mouth lining, thought to be an over-reaction of the immune system.

Also called: feline chronic gingivostomatitis, FCGS, feline stomatitis, mouth inflammation

Stomatitis, in cats usually called feline chronic gingivostomatitis, is severe inflammation of the gums and other soft tissue in the mouth. The tissue is red, swollen and bleeds easily, and ulcers may form at the back of the mouth. It is one of the most painful dental conditions in cats.

The exact cause is unknown. The immune system seems to over-react to plaque on the teeth, and viruses such as feline calicivirus and feline immunodeficiency virus have been linked to it. Cats with both periodontal disease and stomatitis often have a worse time.

Signs include bad breath, drooling, pawing at the mouth, dropping food, eating on one side, chewing hard food reluctantly, weight loss and a rough coat. Some cats cry out when they yawn or eat, and some become withdrawn or irritable. Because cats hide pain, the signs are easy to miss.

Vets diagnose it with an oral exam under anesthesia with dental X-rays, and may do blood tests and biopsies. Treatment usually combines professional dental cleaning, pain relief and the removal of some or all teeth, which clears or greatly improves most cats. Some need long-term medicine. Ask your vet about your cat's options and what to expect after surgery.

Last reviewed November 7, 2026

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Related terms

Periodontal disease Infection and inflammation of the gums and tissues that hold the teeth, the most common dental problem in cats. Tooth resorption A common, painful dental disease in which the body gradually dissolves part of a cat's tooth, often hidden below the gum line. Feline calicivirus A common virus behind cat flu that causes sneezing, eye discharge and painful mouth ulcers, and sometimes severe illness. Anesthesia The medically controlled loss of consciousness and pain sensation that lets a vet perform surgery, dental work or imaging safely. Feline immunodeficiency virus A slow-acting virus, spread mainly by deep bite wounds, that gradually weakens a cat's immune defences.

Related guides

Caring for a cat's teeth Why dental disease is common in cats, how to brush or check your cat's teeth, what signs matter, and how often a vet should look.