Feline calicivirus (aka FCV), is a common virus that affects cats, and is characterized by upper respiratory symptoms, pneumonia, oral ulceration, and occasionally arthritis. It is a some-what mild flu-like condition and rarely causes serious complications, though more serious complications are seen in kittens due to their weaker immune system.

Calicivirus and feline rhinotracheitis virus together are responsible for nearly 85% to 90% of all URIs in cats.

Incidence Calicivirus occurs worldwide and affects all breeds of cats. Vaccination has reduced the incidence of clinical disease, but it hasnít decreased the prevalence of the virus. The virus is spreading, even though fewer cats show symptoms.

Causes Numerous strains of feline calicivirus exist and different strains cause different symptoms (for example, one particular strain can cause ulcers on the paws as well as in the mouth). It usually affects the throat, and sometimes the lungs; it can also infect the intestines. Calicivirus often occurs with another upper respiratory infection, such as feline herpesvirus (FHV), rhinotracheitis virus, or chlamydiosis.

Transmission Calicivirus is spread through direct contact with the saliva, eye and nose discharges, and sometimes the feces of an infected cat. Since kittens share close quarters and are less hygenic than adult cats, rates of infection and transmission are much higher. Higher outbreaks occur in shelters and catteries as well. Outbreaks can occur in overcrowded, poorly ventilated, or unsanitary conditions; and where the cats are poorly fed, or stressed, either physically (extreme temperatures such as ferals often endure) or psychologically (orphaned kittens).

FCV is resistant to many disinfectants and can survive outside the catís body for as long as 8 to 10 days, so it may be present in dishes, litter trays, and clothing, even after a thorough cleaning.

Many cats remain contagious for years, even though they may not show signs of disease thus many are latent carriers.


As it is a virus, treatment is primarily supportive. As with all URIís, hygiene and sanitary precautions are of the utmost importance. Dehydration is also a large risk, particularly with kittens, thus WF recommends the use of a product such as Pedialyte to boost hydration and electrolytes.