Feline calicivirus​​1​ is a virus that is an important cause of upper respiratory infections and oral disease in cats. This virus infects cats throughout the world and can cause disease in both domestic and exotic cat species. Although several different viruses and bacteria can cause respiratory disease in cats, calicivirus is one of the more common infectious agents isolated in cats with a respiratory infection. The other being Felid alphaherpesvirus (see: Wikipedia)