Red mouth or mouth ulcers in a cat
Bright red, raw-looking tissue that bleeds when touched, or ulcers in the mouth, are signs of severe inflammation and pain. In cats this is often chronic gingivostomatitis, but periodontitis, tooth resorption (TR), viral ulcers, kidney disease and tumours can look similar. A cat may keep eating and still be in pain, so the cause needs to be found at an examination.
Important note for owners
A thin red line along the gum margin is gingivitis. If the redness spreads beyond the gums — to the back of the mouth, the palate, the lips or under the tongue — this is typical of gingivostomatitis, and a dental clean alone is not enough.
Most common possible causes
- —Chronic gingivostomatitis (FCGS). It is thought to be an exaggerated immune response to plaque bacteria and other irritants; the exact cause is not fully understood. The gums and the tissue at the back of the mouth are inflamed (caudal stomatitis); feline calicivirus is discussed as an associated factor.
- —Gingivitis, periodontitis, tooth resorption (TR). The redness is limited to the gum margin or concentrated around individual teeth. Affected roots and tooth remnants in the bone are only visible on an X-ray.
- —Juvenile gingivitis. In young cats, during and after the change of teeth, the gums can be bright red, swollen or overgrown (hyperplasia).
- —Acute viral ulcers. In young cats, calicivirus causes ulcers on the tongue and palate, usually together with sneezing and discharge from the nose or eyes.
- —Eosinophilic granuloma complex. An ulcer on the upper lip or a lesion on the tongue or palate, linked to immune and allergic reactions.
- —Kidney disease. In chronic kidney disease, ulcers may appear in the mouth and the breath may smell of urine or ammonia. Increased thirst and weight loss are common.
- —A tumour. A non-healing ulcer or swelling, especially under the tongue in an older cat, may turn out to be squamous cell carcinoma. It is easy to mistake for stomatitis.
When not to postpone an exam
- ✓Red, raw-looking gums or oral tissue that bleed when touched
- ✓Drooling, sometimes with blood, and strong bad breath
- ✓Your cat walks away from the bowl, drops food or cries out while eating or yawning
- ✓Your cat is losing weight, grooming less or pawing at the mouth
- ✓An ulcer or swelling that does not heal
Urgent help needed
- ✓Your cat has not eaten for more than a day — cats should not go without food for long
- ✓Signs of dehydration: not drinking, lethargy, dry and tacky gums
- ✓Active bleeding that will not stop
- ✓Difficulty breathing
- ✓Sudden weakness or a sudden deterioration in general condition
- ✓Sudden ulcers and drooling after contact with household chemicals or essential oils, or after chewing a cable
What you can do at home
- ✓Switch to soft wet food or pâté and warm it slightly: warm, not hot, food is easier to eat.
- ✓Keep track of how much your cat actually eats and weigh it every week: weight loss is an important signal.
- ✓If your cat allows it, gently lift the lip, photograph the gums from the side and send the photos for an online consultation on Telegram. Photos help judge urgency, but they do not replace an examination.
What not to do at home
- —Don't give anything from your own medicine cabinet: human painkillers, including paracetamol, are deadly for cats
- —Don't force the mouth open or brush inflamed gums — it is very painful
- —Don't give leftover antibiotics or steroids without a vet's examination — they mask the signs but do not remove the cause
- —Don't use mouth rinses, gels or sprays as a substitute for treatment
What diagnostics may be needed
- ✓Consultation: a look at the mouth as far as your cat allows, weight and general condition
- ✓Examination of the whole mouth under anaesthesia as part of COHAT, including the back of the mouth and the area under the tongue
- ✓Full-mouth dental radiography: tooth resorption (TR), periodontitis, retained roots
- ✓Blood tests: kidney function and, when clinically indicated, screening for infectious diseases
- ✓Biopsy of atypical lesions and ulcers that do not heal
A photo, or even an examination without anaesthesia, does not show the back of the mouth, the roots, resorption under the gums or fragments left after previous extractions. And whether an ulcer is caused by a tumour or an eosinophilic lesion cannot be reliably judged by its appearance — that requires a biopsy.
Unfamiliar term in the diagnosis?If the report mentions TR, FCGS, pulpitis or a periodontal stage, the glossary explains each term briefly.GlossaryHow treatment may proceed
- ✓I choose the treatment after diagnostics, depending on the cause
- ✓For gingivostomatitis — extraction of all premolars and molars and, if the inflammation also involves the canines and incisors, of all teeth; completely, with their roots, and with check X-rays after extraction
- ✓For many cats this is the most effective approach, but the response varies: some cats need additional medical therapy and follow-up checks
- ✓Pain relief prescribed by a vet and soft food while the mouth heals
- ✓Other causes are treated according to the diagnosis, together with your regular vet or an oncologist when needed
Related services
Related clinical case
Generalized Gingival Hyperplasia in a Maine Coon Kitten: Gingivectomy and Periodontitis Treatment
View case →Similar symptoms
Related articles
Frequently asked questions
Gingivitis is inflammation of the gum margin only. In chronic gingivostomatitis the redness spreads beyond the gums — to the back of the mouth, the palate and under the tongue — and is usually very painful. The two can be told apart for certain, and any associated dental problems found, after an examination under anaesthesia and X-rays.
In gingivostomatitis, medicines mostly bring only temporary relief, because the plaque on the teeth keeps the inflammation going. Extraction is the most effective approach for many cats, and once healed, most of them eat wet food and often dry food too. I don't promise a complete cure: some cats need additional therapy.
Gingivostomatitis itself is not considered a contagious disease. But calicivirus, which is associated with it and causes acute ulcers in young cats, is contagious. Whether testing is needed and how to manage contact with other cats is something your vet will advise on after the examination.
Ask Luna about your case
Briefly describe what you see — Luna will suggest whether to book and what to prepare.