Feline Infectious Peritonitis (FIP) is a viral infection caused by a coronavirus. Initial exposure usually results in either a mild upper respiratory or intestinal disease. Most cats completely recover, but a small percentage develop a very serious and fatal form of the disease.
Cats that develop this lethal form typically show weight loss, chronic recurring fevers, and may show ocular, central nervous system, kidney, or liver disease, as well as abnormal accumulations of fluid in either the abdominal or chest cavities. This form of the disease is generally considered to be non-treatable. Fortunately, FIP is not commonly seen in our area. This past year, I only saw two confirmed cases of the lethal form.
An FIP vaccine has been available to veterinarians since 1991, but because it is still the subject of considerable controversy, I am not presently recommending it in most household situations.