Feline calicivirus causes a mild to serious respiratory illness.  Cats become infected by inhaling or swallowing the virus, and signs of illness may develop within 2 to 10 days of exposure.  Early signs include runny eyes and nose, sneezing, depression, and poor appetite.  Ulcers may develop on the tongue and hard palate, and most infected cats drool heavily.  The illness lasts 1 to 4 weeks.  Though most cats recover, fatalities do occur.  Young kittens are most likely to be severely affected.  Some cats that recover from the initial disease may continue to shed the virus for weeks or even years.

A vaccine in available for prevention of calicivirus infection.