What is Feline Infectious Peritonitis (FIP)?

Feline infectious peritonitis (FIP) is a fatal viral disease caused by a strain of virus called feline coronavirus (FCoV). This virus is carried by many cats worldwide. FIP is much more prevalent in multi-cat households, shelters, and breeding colonies. Most cats carry the feline enteric coronavirus (FECV) which, rarely causes disease in itself. When the feline coronavirus mutates into a strain of the virus that has the ability to cause disease it is referred to as the FIP virus. It is fortunate that the mutation only occurs rarely.

How is FIP Transmitted?

FECV lives in the cells of the intestinal tract and is shed in cats’ feces. Cats become infected with FECV after they ingest the virus when they groom or eat. The mutant feline infectious peritonitis virus (FIPV) that causes the disease is not contagious to other cats. The exact cause of the mutation of the virus is not known. FIPV lives and replicates inside a type of white blood cell and not in the intestines. So once the virus mutates, it is not shed in cats’ feces.

cat with collar

Two Forms of FIP

Wet (effusive)

The wet form of FIP results in fluid accumulation in body cavities such as the abdomen and chest. It causes abdominal distension and/or difficulty breathing. This fluid is often a yellow color.

Dry (non-effusive)

In the dry form of FIP, inflamed lesions are found throughout the cat’s body, including the eyes, kidneys, liver, and nervous system. Symptoms depend on which organ is most affected by disease.

Signs & Symptoms

There are no symptoms unique to FIP. However, in either form of FIP, cats commonly show vague symptoms such as:

  • Loss of appetite
  • Weight loss, or for kittens a failure to gain weight
  • Lethargy
  • Fluctuating fever that is not responsive to antibiotics

How Can I Prevent My Cat from Getting FIP?

Preventing your cat from contracting FIP is difficult because there are many factors that contribute to the development of the disease. Cats in stressful conditions, such as shelters or multi-cat households, have been shown to be at an increased risk for development of FIP. It is important for your cat to visit your veterinarian for regular checkups. Also try to minimize exposure to infectious diseases and by keeping your cat up to date on vaccinations. And, remember to clean your cat’s litter box daily and locate them away from food and water dishes.

Testing for FIP

Currently, there isn’t a test to screen healthy cats for the risk of developing FIP. To diagnose FIP in a sick cat, veterinarians must piece together several diagnostic clues. These include clinical signs and common findings on lab work that correlates with FIP, as well as ruling out other diseases. Analysis of any fluid in the abdomen or chest helps make an accurate diagnosis.

FIP Vaccine

There is no vaccine currently available.


There are no legally approved treatments in North America and many other locations for cats diagnosed with FIP. Some countries, for example, the United Kingdom and Australia, have legally approved antiviral drugs available for treating FIP. Currently, several veterinary research groups are working on different approaches to treat the disease. You can help keep your cat comfortable and reduce pain with supportive care by working with your veterinarian.

Contributed by Dr. Susan Gogolski DVM, DABVP (Canine/Feline), Dr. Vicki Thayer, DVM, DABVP (Feline), Dr. Amy Lowe, DVM