FIP: Feline Infectious Peritonitis in Cats


FIP in cats is a serious and usually fatal infection. It is not easy to diagnose, has very few treatments, and is not curable. This terrible condition is not easy to understand, and scientists are still studying and learning more about it.

What Causes FIP in Cats?

FIP is caused by a type of feline enteric coronavirus. Coronavirus is spread from cat to cat through fecal-oral transmission. Cats ingest the virus by cleaning themselves off after contacting the stool of an infected cat.

There are many strains of coronavirus, and most of them cause no disease in cats. A few of these viruses can cause mild fever and flu-like signs in cats, but these are mild illnesses that resolve on their own. However, in 5-10% (Feline Infectious Peritonitis, 2002) of infected cats, the virus is not so mild. Scientists believe that, in these cases, the virus mutates inside the body, and then the cat's own immune system mounts an inappropriate response to it and aids in its spread. The virus travels throughout the cat's system in the white blood cells, causing widespread inflammation. The inflammation leads to fever, organ failure, and possibly fluid accumulation in the cat's body cavities: the chest and/or abdomen. When this fluid accumulation occurs, the cat is said to have the wet form of FIP. Cats without the fluid have the dry form. Both forms are fatal.

Which Cats Are at Risk for Developing FIP?

Any cat that contracts a coronavirus may develop FIP, and these viruses are quite common in the environment. However, the following groups of cats seem to develop FIP more commonly than others, probably because of immature or suppressed immune systems:

Signs of FIP

When a cat is infected with feline enteric coronavirus, there are often no signs of illness. Some cats may have a slight fever, mild respiratory signs, or some diarrhea that clears up on its own in a day or two. Very few cats that contract coronavirus end up developing FIP, but those that do may not show signs for months or years after the original coronavirus infection. Signs when they do occur may include:

Diagnosis of FIP

Diagnosing FIP in cats is extremely difficult. There are multiple tests that can be done, but these only detect whether the cat has antibodies to feline enteric coronavirus. Since many cats are exposed to and develop antibodies to coronavirus but don't go on to develop FIP, this type of test doesn't tell the veterinarian much about the current disease process.

Diagnosing FIP is done by ruling out other illnesses and putting puzzle pieces together that point toward FIP. Some of those puzzle pieces include:

Treatment of FIP

Unfortunately, there is no effective treatment or cure for FIP in cats. Some treatments may help affected cats feel better and live a bit longer. Some or all of the following may be used as supportive treatments for cats with FIP:

There are drugs that modulate immune responses as well as anti-viral drugs being tested for their potential to help cats with FIP in hopes that better treatments can be developed for this disease.

Prevention of FIP

Because FIP is the result of the mutation of the common feline enteric coronaviruses, it is difficult to prevent cats from being exposed and impossible to determine whether a cat will experience the mutation to FIP. Still, there are a few things you can do to try and decrease the chance that your cat will be exposed to coronavirus.

FIP is a frustrating, heart-breaking disease in cats, and hopefully more research will shed light on better ways to diagnose and treat it.

You May Also Like These Articles:

How Long Do Cats Live?

Feline Immunodeficiency Virus

Feline Lower Airway Disease

Cats Snoring: Normal or Abnormal?

How to Be Prepared for Your Cat's Veterinary Bills

Bubonic Plague: Cats are Highly Susceptible

Cats and Ebola

Feline Leukemia Virus

Disclaimer: This website is not intended to replace professional consultation, diagnosis, or treatment by a licensed veterinarian. If you require any veterinary related advice, contact your veterinarian promptly. Information at is exclusively of a general reference nature. Do not disregard veterinary advice or delay treatment as a result of accessing information at this site. Just Answer is an external service not affiliated with