Inflammatory Stomatitis

Inflammatory stomatitis is an immune-mediated disease in which the patient develops severe redness, pain, and irritation of the gums.


There are several potential causes of inflammatory stomatitis, but in many cases, a cause cannot be found. (Rarely, the inflammation is a response to exposure to an oral irritant such as a house plant or cleaning solution.) There are some patients that develop inflammation after a medication or vaccination causes an aberrant immune response.

Occasionally, normal oral bacteria can trigger an overzealous inflammatory response.

Some pets are sensitive to certain types of protein or additives in food.

Some pets appear to have a genetic predisposition to chronic, unexplained inflammation of the mouth.  This is more common in certain breeds of cats.

Clinical Signs

Poor appetite, halitosis, discharge, redness, and pain are the most common signs. Patients may rub at their mouths, drop food, or chew with exaggerated movements. These signs may be chronic and wax and wane, or come on suddenly and be quite severe. Some patients will have a partial response to antibiotics because it reduces the secondary bacterial infection in the mouth.


Because there are a variety of potential causes of inflammatory stomatitis, your veterinarian may suggest several tests to determine the cause.

Blood tests may be used to look for other causes of inflammation, such as kidney or liver disease, as well as to assess your pet’s general health status.

Radiographs (X-rays) are often taken to look for tumors because aberrant immune responses are sometimes seen as secondary to tumors in other organs.

An ultrasound may be used if an abdominal tumor is suspected.

The biopsy of the mouth is the most definitive way to confirm inflammatory stomatitis. The biopsy needs to be performed under general anesthesia because the mouth is generally quite sensitive

Results of biopsy samples are usually available within 5-10 days of the procedure.


Treatment of inflammatory stomatitis depends on the cause and characteristics of the inflammation determined by biopsy exams or other tests.

If the biopsy suggests that allergy to food or additives may play a role in the inflammation, a dietary change may be required. Short or long-term feeding tubes are sometimes necessary to address malnutrition during the period of significant oral pain and inflammation.

Many biopsies reveal that the inflammation has no apparent underlying cause, meaning that the immune system is laying down inflammatory cells in the mouth with no apparent underlying trigger. This type of overactive immune response is also seen with asthma, inflammatory bowel disease or eczema, where the immune system causes excess inflammation of the lungs, bowel, or skin. These cases of inflammatory stomatitis are treated with drugs that calm the immune response.

In some cases, there is more than one cause for chronic oral inflammation, and multiple therapies are necessary.


The prognosis for inflammatory stomatitis is generally good with directed therapy. It is sometimes difficult to orally medicate a patient with oral pain; this is usually a short term challenge. It is rare that the disease is life-threatening, but for some patients, quality of life continues to be poor even with therapy.

As with most inflammatory diseases, inflammatory stomatitis is a nuisance to the pet as well as the family. The oral pain, discharge, and odor generally improve in the early weeks. Many cases are somewhat difficult to treat and require multiple trials before a balance is established with appropriate medication. It is important to be patient in the first few weeks and months after diagnosis.

Long Term Follow-Up

Some of the medications to treat inflammatory stomatitis (particularly immunomodulators) have side effects and require periodic monitoring with blood tests. Your veterinarian will inform you if such tests are necessary.

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