Dictionary.net

A species of CORONAVIRUS infecting cats of all ages and commonly found in catteries and zoos. Cats are often found carrying the virus but only a small proportion develop disease. Feline coronavirus and Feline infectious peritonitis virus (FIPV) are virtually the same virus in genetic and antigenetic terms, and are morphologically indistinguishable. Since they only differ in their disease potential (with FIPV causing a more serious illness), they are considered biotypes of each other. (From Hoskins, JD. Update on Feline Coronavirus Disease. http://maxshouse.com.FIP%20Update.htm (April 3, 2001))