FIP - Feline Infectious Peritonitis

A friend left me a message this week telling me that her 7-month old kitten was ill and the family veterinarian suspected feline infectious peritonitis (FIP). With trepidation I called her back, as this is one of those unfortunate diseases that can affect young kittens, create a sense of helplessness for veterinarians, and great sorrow and loss for cat owners whose expectation for a lifetime of companionship is cut painfully short.

Identified in the 1980s by Dr. Neils Pederson at UC Davis, coronavirus is the root cause of FIP.  It is a common intestinal virus, which may manifest as mild diarrhea or even have no clinical signs when a cat is exposed. Most cats will clear the virus within weeks to months, but a small number of cats exposed to the virus can become carriers.  In a multi-cat household or breeding facility, a carrier of the virus can potentially infect the other cats through fecal and salivary contact. In the infected population, about 10% of cats develop the lethal form of FIP. While many cats exposed to the coronavirus do not become ill, those who mutate to FIP will show signs of illness such as weight loss, lethargy, fever and depression. Some kittens may have breathing changes if they develop fluid in their chest, while others will have abdominal distension from fluid in their abdomen.       

Prevention is challenging, as one cannot predict which cat in a group will mutate the coronavirus into FIP.  Maintaining good husbandry, decreasing population density and not breeding cats that have a high titer (concentration) of the coronavirus are some techniques recommended.  In a household where a cat has been diagnosed with coronavirus, some recommend not getting a new cat for a number of weeks to months and thorough cleaning of or destruction of the litter box and bedding of the affected pet. The virus can live for some time outside the body (up to six months), but is not resistant to good cleaning with detergents, bleach or disinfectants.

Diagnosis of feline infectious peritonitis is made based on age, history and an increase of the proteins called globulins that show up in blood tests. Changes in the liver values can often occur and many cats have either breathing changes or intestinal signs such as vomiting, diarrhea or weight loss. Definite diagnosis of FIP can be difficult and may include an expensive or invasive biopsy. Due to the poor prognosis and potential to affect other cats in the household, some will take the steps to reach a definite diagnosis in their pets.  Most diagnoses are made in cats 3 to 12 months of age, which is part of the heartbreak of this disease.

Treatment at this time is limited to supportive care and use of steroids to minimize the inflammation caused by the mutated virus. A newer therapy for FIP called omega interferon was introduced with early clinical trials in the past few years, but the response has not been as positive as initially hoped.  For now, the hopes are we see fewer and fewer cases of this devastating disease by prevention and decreasing situations where the virus has opportunities to spread and mutate.

Much information is available on the internet about FIP and the research and discovery as well as potential treatments for this disease continues forward. Here are a few links with information about the disease:;

Blog Post Author: 

Merrianne Burtch, DVM, DACVIM