Gingivitis in cats is caused by the buildup of bacterial plaque along the gumline, which triggers an inflammatory immune response in the surrounding tissue. It’s extremely common: periodontal disease is the most frequently diagnosed condition in cats seen by veterinarians, affecting an estimated 15% or more of cats in primary care. The good news is that gingivitis, the earliest stage of gum disease, is reversible with proper care. Left untreated, it progresses to periodontitis, which permanently damages the structures supporting the teeth.
How Plaque and Tartar Build Up
The process starts within hours of eating. A sticky film of bacteria, called plaque, forms on the tooth surface after every meal. Within 24 hours, that plaque begins to harden by absorbing calcium and other minerals from saliva. Over time, the mineralized plaque becomes tartar, a rough, cement-like deposit that clings to the tooth and sits right against the gumline.
Tartar matters because it creates the perfect environment for more bacteria to accumulate. Its rough surface gives plaque new footholds, and it pushes deeper beneath the gumline where brushing can’t reach. The bacteria in this subgingival plaque release toxins that irritate the gum tissue, and the cat’s immune system responds with inflammation. That inflammation is gingivitis.
The Immune System’s Role
In most cats, gingivitis is a proportional response to plaque bacteria. Remove the plaque, and the inflammation resolves. But some cats develop a disproportionate immune reaction, where the body essentially overreacts to normal levels of oral bacteria. This leads to a more severe and chronic condition called feline chronic gingivostomatitis (FCGS), which causes intense, painful inflammation of the gums and the tissue at the back of the mouth.
In cats with FCGS, the immune system floods the gum tissue with inflammatory cells, particularly certain types of white blood cells that attack the lining of the mouth. The body also produces elevated levels of chemical signals that keep the immune response running in a loop, causing persistent tissue damage and remodeling. Researchers believe this represents a fundamental breakdown in the immune system’s ability to regulate itself rather than a simple reaction to dirty teeth. The condition is considered multifactorial, meaning no single trigger explains it.
Viral Infections That Worsen Gum Disease
Several common feline viruses are strongly associated with chronic oral inflammation. Feline calicivirus (FCV), feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), and feline herpesvirus have all been linked to more severe gingivitis and stomatitis.
FCV is the most studied connection. This virus causes upper respiratory infections and oral ulcers, and it’s found at much higher rates in cats with chronic gingivostomatitis. Nearly 100% of cats with FCGS test positive for calicivirus antibodies, compared to a much lower rate in the general cat population. Researchers have even reproduced the condition in laboratory settings by introducing calicivirus strains taken from cats with chronic stomatitis. Cats carrying higher loads of the virus are more likely to develop tongue ulcers. That said, many cats carry calicivirus without developing mouth problems, so the virus alone isn’t enough to cause disease. It likely acts as one trigger among several in cats whose immune systems are already prone to overreacting.
FIV and FeLV both suppress the immune system, which can allow oral bacteria to flourish unchecked and make the body less effective at managing normal plaque levels.
Breeds With Higher Risk
Genetics play a measurable role. The UK’s largest feline dental disease study, conducted by the Royal Veterinary College, found clear breed differences in diagnosis rates. Siamese cats had the highest annual rate of periodontal disease at 18.7%, followed by Maine Coons at 16.7% and British Shorthairs at 15.5%. Crossbred cats were also frequently affected at 15.4%.
Some of these breed predispositions relate to tooth crowding, jaw shape, or inherited tendencies toward stronger inflammatory responses. Siamese cats in particular are known for developing gingivitis at younger ages than other breeds, sometimes before their first birthday.
How Diet Affects Gum Health
The texture of your cat’s food has a direct effect on plaque accumulation. Dry kibble provides a mild abrasive action as the cat chews, physically scraping some plaque off the tooth surface. Wet food doesn’t offer this mechanical cleaning effect and tends to cling to teeth more easily.
Research comparing cats fed exclusively dry versus wet diets found measurable differences across several markers. Cats on wet diets had higher gingivitis scores, thicker plaque deposits on their premolars, and greater tartar coverage than cats eating dry food. Diet also influences the oral environment in subtler ways: food texture affects saliva production, and nutrient composition shapes the metabolic activity of the bacteria living in plaque.
This doesn’t mean wet food is bad for cats or that dry food prevents gingivitis on its own. Many cats eat wet food their entire lives without significant gum disease, and dry kibble alone is not a substitute for dental care. But if your cat is prone to plaque buildup, the texture of their diet is one factor worth discussing with your vet.
What Gingivitis Looks Like at Each Stage
Veterinarians grade gingivitis on a scale from 0 to 3:
- Grade 0: Normal, healthy gums. The tissue is pink and firm with no swelling.
- Grade 1 (mild): Slight swelling and a subtle increase in redness along the gumline. Most cat owners won’t notice this stage.
- Grade 2 (moderate): Obvious swelling and redness. The gums bleed when probed during a dental exam.
- Grade 3 (severe): Significant swelling with deep redness. The gums bleed spontaneously, without any pressure applied.
Cats are good at hiding discomfort, so many owners don’t realize their cat has gingivitis until it’s moderate or severe. Signs to watch for include bad breath, drooling, difficulty eating, pawing at the mouth, and red or swollen gums visible when your cat yawns.
Why Some Cats Get Gingivitis and Others Don’t
Two cats in the same household, eating the same food, can have completely different dental health. That’s because gingivitis results from the intersection of multiple factors: the bacterial load in the mouth, the individual cat’s immune response, viral status, breed genetics, diet, and age. Older cats accumulate more tartar over time and are diagnosed more frequently. Cats with suppressed immune systems from FIV or FeLV face a steeper challenge keeping oral bacteria in check.
The single biggest modifiable factor is plaque control. Daily tooth brushing is the gold standard for prevention, though brushing at least three times a week is considered the minimum to meaningfully reduce plaque and slow tartar formation. Starting when a cat is young makes the habit easier to establish. For cats that won’t tolerate brushing, dental treats, water additives approved by the Veterinary Oral Health Council, and regular professional cleanings help fill the gap.
Because gingivitis at its earliest stage is fully reversible, catching it early and addressing the plaque that caused it can prevent progression to periodontitis, where bone loss and tooth damage become permanent.