Feline infectious peritonitis (FIP) is a relatively rare but fatal disease of cats. Many cats are exposed to the virus that can cause FIP when they are young, and most develop only a mild case of diarrhea and no further problems. In some cases, however, the virus can mutate into the form that causes FIP. Most cats diagnosed with FIP are under three years of age.
Cats with FIP can have a fever; become depressed, lethargic, and inappetent; lose weight; develop eye infections and neurologic abnormalities; and have difficulty breathing. In the "wet" form of the disease, fluid collects within a cat's abdominal and/or chest cavity. Cats with the "dry" form do not have these characteristic fluid accumulations, which makes diagnosis more difficult. A veterinarian may suspect that a cat has FIP based on its history, physical exam, diagnostic testing (e.g., blood work, a urinalysis, fecal examinations, and x-rays) to rule out other diseases that cause similar symptoms, and examination of a sample of fluid collected from the abdomen or chest, but definitive diagnosis can be difficult. Immunological testing is available through diagnostic labs, but it cannot differentiate between animals that have been exposed to the virus and only had a mild case of diarrhea in the past and those that have gone on to develop FIP.
Treatment for FIP is limited to supportive and symptomatic care. When a cat's quality of life becomes unacceptable, euthanasia is the most humane option available. A vaccine for FIP is available, but its effectiveness is questionable and its use is not generally recommended.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008