Feline infectious peritonitis sometimes known as FIP, is the name given to an uncommon, but usually fatal, aberrant immune response to infection with feline coronavirus. Most infections are either asymptomatic or cause diarrhea, especially in kittens, as maternally derived antibody wanes at between 5 and 7 weeks of age.
FCoV is common in places where large groups of cats are housed together indoors in large facilities, such as animal shelters or catteries. The virus is shed in feces and cats become infected by ingesting or inhaling the virus, usually by sharing cat litter trays, or by the use of contaminated litter scoops or brushes transmitting infected microscopic cat litter particles to uninfected kittens and cats.
There are two main forms of FIP: effusive (wet) and non-effusive (dry). While both types are fatal, the effusive form is more common and is considered more dangerous than the non-effusive form. Symptoms may include: