Feline calicivirus (FCV) is the virus most often found behind chronic gingivostomatitis, the painful inflammation of gums, cheeks and the back of the mouth that makes a cat stop eating. The disease is graded 0 to 4 by how much of the mouth is red and ulcerated, and that grade sets everything else: how often the cat is rechecked, whether dental radiographs are needed, and how aggressively the mouth is managed. A grade 3 mouth left alone for 6 months usually comes back as grade 4 with 2 or 3 teeth lost.
Why a respiratory virus ends up in the gums
FCV infects the oral mucosa and tonsils, and a share of cats stay carriers, shedding virus for months to years after the original sniffles. The virus itself does not eat gum tissue; it keeps the local immune response switched on, and the result is lymphoplasmacytic inflammation that spreads from the gum line to the fauces. Stress, crowding, a new cat in the house, or a dental cleaning that is followed by 2 weeks of pain can each push a grade 2 mouth to grade 3. Vaccination reduces severe disease but does not stop infection or carriage, so a vaccinated cat can still develop the chronic form.
The 0 to 4 grading used at every visit
Grading is done with the cat awake for the first pass and under anesthesia for the real score, because the back of the mouth cannot be seen otherwise. Four things are scored: how far the redness runs from the gum margin, whether ulcers are present, whether the cat flinches when the jaw is opened, and how much the cat eats.
| Grade | Redness beyond gum margin | Ulcers | Food intake | Next recheck |
|---|---|---|---|---|
| 0 | 0 mm | none | normal | 12 months |
| 1 | 1 to 2 mm | none | normal | 6 months |
| 2 | 3 to 5 mm | none | soft food preferred | 3 months |
| 3 | over 5 mm, fauces red | 1 to 2 | drops food, cries | 6 weeks |
| 4 | whole mouth | 3 or more | refuses food 24 h | 7 days |
What the workup has to include
A full oral exam under anesthesia with a probe, plus full-mouth dental radiographs: root resorption and fractured roots are common in these mouths and change the plan. Biopsy of the fauces confirms lymphoplasmacytic stomatitis and rules out squamous cell carcinoma, which can look identical at 1 metre and is the reason no cat with a grade 3 mouth should be treated on appearance alone. Swab the oropharynx for FCV PCR, and test FeLV and FIV, since both worsen the picture. Bloodwork gives the baseline: creatinine 1.6 to 2.4 mg/dL, total protein, albumin, and a urine concentration, because kidneys and mouth often fail together after 10 years of age.
What a 6-month recheck actually contains
Six months is the standard interval once the mouth is stable, and it is a fixed package rather than a look in the mouth. Weight on the same scale (a 5 percent drop in 6 months is a flag), a body condition score, a repeat 0 to 4 grade with 3 photographs of the same angles, a pain score on jaw opening, bloodwork if the cat is over 8 years, and radiographs of any tooth that was doubtful at the last visit. If the grade has not moved and the weight is stable, the next visit is 6 months later. If the grade went up by 1, the interval drops to 6 weeks.
Numbers the owner can log between visits
Time to finish a meal is the most sensitive home measure: a cat that took 4 minutes and now takes 12 is telling you the mouth hurts. Log it 3 times a week. Weigh weekly and write it down, because a 200 g loss in a 4 kg cat is 5 percent. Note dribbling, pawing at the face, and whether the cat chews on one side. A head-shy cat that stops grooming is at grade 3 more often than not. Photograph the gum line every 2 weeks with the same light, so a change of 2 mm is visible instead of remembered.
What counts as an emergency
Go the same day if the cat has eaten nothing for 24 hours, or has taken only water for 48 hours; a cat over 5 kg that stops eating loses condition fast and hepatic lipidosis can start within 72 hours. Go within the hour for drooling blood, a jaw that will not close, swelling under the eye or below the jaw, breathing with the mouth open, or a temperature above 40 degrees Celsius. Weight loss of 10 percent in 2 weeks, or 2 days of not grooming and hiding, is urgent but not an hour-one emergency. Never wait a weekend with a cat that is drooling and not eating: dehydration in a cat with a sore mouth compounds within 48 hours.
The workable plan
- Get a grade on paper at the first visit, with 3 photos, so the next visit has something to compare against.
- Book the 6-month recheck at checkout instead of calling later; the interval is the treatment.
- Keep a meal-time log for 3 weeks before each visit, and bring the numbers, not an impression.
- Ask for full-mouth radiographs at the first workup and again at 12 months, not just when a tooth looks bad.
- Weigh weekly and act on a 5 percent drop, because weight is the earliest reliable sign that the mouth is worse.
Costs of the anesthesia, radiographs and biopsy are itemized in the cost tool, and a cat that also vomits or loses weight should be worked up for gut disease alongside the mouth, starting with IBD and chronic vomiting and the step-by-step plan in the chronic vomiting plan.
Terms mentioned in this article
Frequently asked
Does calicivirus always cause chronic stomatitis?
No. Many cats clear the acute infection and never develop mouth disease, and some stay carriers with no signs at all. What raises the risk is a mouth that stays inflamed after the initial episode, plus stress, crowding and dental disease; that combination is what pushes a mild grade into a chronic one.
Why is 6 months the standard recheck?
Because the grade moves slowly enough that 6 months catches a change before teeth are lost, and fast enough that a 1-grade rise still gets a 6-week follow-up. The visit is a fixed package: weight, body condition, a repeat 0 to 4 grade, photos, and radiographs of doubtful teeth.
When does a cat with stomatitis need urgent care?
No food for 24 hours, only water for 48 hours, drooling blood, a jaw that will not close, facial swelling, open-mouth breathing, or a temperature above 40 degrees Celsius. A cat that stops eating can start hepatic lipidosis within 72 hours, so a weekend of waiting is a real risk.