Mystery Cat Mouth Disease

CatChannel veterinary expert Arnold Plotnick, DVM, considers reasons why and treatment for a cat whose mouth is infected and bleeding.

Q: The inside of Sammy’s, my cat’s, mouth has inflamed gums at the top and bottom and his breath is bad. Sammy will turn 1 year old in May, but I noticed this problem when he was eight months old. I went to my vet and the doc said he could have a viral infection of some sort. The vet thought it was strange for a cat that age to have this, and I was given some medicine.
Sammy received a Vetalog injection and an antibiotic injection. I was then given some Clindamycin drops for his mouth and told to come back five days later for a re-check examination. His mouth showed no improvement. I was then given Clavamox drops for his mouth and told to come back a week later. Still, no improvement. The vet thought it would get better, but, it did not. When I took Sammy for his re-check, he was given a Baytril injection and a Depomedrol injection and Baytril tablets (cut in half) for Sammy to take. I was told to come back a week later and still no improvement. After the re-check exam, I was then given lysine gel and more Clindamycin drops for his mouth.

Another vet said Sammy may have some kind of viral infection and tested him for FeLV and FIV; both came back negative. The vet said removing Sammy’s teeth could help with his mouth and it was to remove his teeth, but didn’t suggest it because Sammy was still a kitten. So, my vet really didn’t know what this problem was. My vet suggested I come back and have a biopsy done to my cat’s mouth to analyze the red inflammation.
Sammy continues to eat and play normally and I hoped the inflamation would eventually go away. It still hasn’t. I did some research and stumbled across a bacterial disease in cats called Bartonella. The examples showed the same red inflammation. Do you think this might possibly be Bartonella? I am frustrated because I’ve never had to deal with something like this. I have three other cats in my household and none have the same problem, though my vet said it could be contagious. All of the cats, including Sammy, are up-to-date on their vaccinations.

A: I suspect your cat has a condition called lymphocytic/plasmacytic gingivitis and stomatitis (LPGS), an  inflammatory condition that causes a great deal of discomfort to many cats mouths. Cats with LPGS usually exhibit chronic, severe inflammation and ulceration of the gums, back of the throat and often other structures inside the mouth. The exact cause of LPGS is unknown, but it is most likely a combination of various factors. One theory is that some cats’ gums are hypersensitive to bacterial plaque. Small amounts of plaque will cause the immune system to overreact and mount an exuberant inflammatory response, sending large numbers of inflammatory cells, mainly lymphocytes and plasma cells (hence the description “lymphocytic/plasmacytic”) into the gums and oral tissues. I don’t think this is the case with your cat, because he’s so young; he hasn’t been around long enough to develop significant plaque. Suppression of the immune system has also been theorized as a cause or contributing factor in LPGS. Infection with the feline leukemia virus (FeLV) and/or the feline immunodeficiency virus (FIV) is known to suppress the feline immune system and may play a role in some affected cats, however, your cat tested negative for both viruses. Other infectious causes have been implicated, including feline calicivirus (FCV). A genetic predisposition is likely in some breeds. In most cases, we never identify a cause.

Many attempts have been made to implicate the bacteria Bartonella as a cause of gingivitis in cats, but the evidence  for this is sorely lacking. Many cats test positive for Bartonella and have no gum inflammation at all. Some cats with gum inflammation test positive for Bartonella, but this does not mean that the Bartonella causes the inflammation. In cats with gingivitis who test positive for Bartonella, treating them for Bartonella rarely causes improvement. The antibiotic usually prescribed is azithromycin. I’m surprised your vet didn’t prescribe it. He seems to have thrown every other antibiotic at your cat.

Your cat seems to not be bothered by his inflamed gums. As long as your cat is able to eat comfortably and is not showing any signs of oral discomfort (such as difficulty eating, excessive drooling, pawing at the mouth, etc.), I would just have it monitored regularly by your vet. Your cat will need regular dental cleanings to prevent plaque buildup which can exacerbate the problem. If serious problems develop in the future (there’s no predicting), treatment with antibiotics and/or steroids may be necessary. The use of antibiotics and anti-inflammatory drugs, however, offers only a short-term “fix.” Eventually, most cats become non-responsive to medical treatment and will require extraction of all of the teeth except the canines (the “fangs”). In most cases, extraction alone successfully reduces the inflammation and allows the cat to eat and live normally. Cat owners often worry that their cat won’t be able to eat after full-mouth extraction, however, most cats tolerate extractions very well and can eat moist food readily, with many cats able to crunch on dry food after the extraction sites have fully healed.

Cats with LPGS are likely facing a lifetime of frequent veterinary visits and treatments. With vigilant monitoring and conscientious veterinary care, however, cats with LPGS can live comfortable happy lives.

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