Feline calicivirus infection
Also called Cat flu (with herpesvirus), FCV
One of the commonest viruses of cats. It causes painful mouth ulcers and mild cold-like signs, and sometimes pneumonia in kittens, limping, or rare severe outbreaks.
Cause and spread
- Cause
- Feline calicivirus (FCV), a very variable RNA virus that resists many disinfectants.
- How it spreads
- Highly contagious through contact between cats and contaminated surroundings, especially in multi-cat homes, shelters and catteries with poor hygiene.
Signs to watch for
- Painful sores on the tongue and in the mouth, with drooling
- Sneezing and runny eyes or nose
- Fever and loss of appetite
- Pneumonia in kittens
- Shifting limping in some cats
- Long-lasting gum inflammation in some cats
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
RT-PCR on mouth, throat or eye swabs is the best test, but a negative result does not rule infection out, and healthy cats can test positive. A positive result in a cat with typical signs makes FCV the likely cause.
Prevention and control
- Vaccinate: calicivirus is a core cat vaccine; vaccination usually protects from disease but not infection
- Keep groups small and stable (not more than three cats) and keep good hygiene
- Use disinfectants based on sodium hypochlorite, potassium peroxymonosulphate or chlorine dioxide
- Vaccinate cats that have recovered, since immunity is not lifelong
Where this information comes from
- Feline Calicivirus Infection (ABCD guideline) · European Advisory Board on Cat Diseases (ABCD)
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.