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) that occurs worldwide. This virus is actually carried by many cats, though it is much more prevalent in multi-cat households, shelters, and breeding colonies. The form of coronavirus that is carried by most cats is the feline enteric coronavirus (FECV) which, rarely causes disease in itself. It is when the feline coronavirus mutates into a strain of the virus with the ability to cause disease that it becomes referred to as the FIP virus. Considering how many cats carry FECV, it is fortunate that the mutation only occurs rarely.

How is FIP Transmitted?

The benign or usually harmless FECV inhabits cells of the intestinal tract and is shed in a cats’ feces. Cats become infected after ingesting the virus during grooming or eating. The mutant feline infectious peritonitis virus (FIPV) responsible for causing the disease is generally not considered to be contagious among cats. The exact cause of the mutation of the virus is not known and it is likely that it mutates for a multitude of reasons. The FIPV lives inside a type of white blood cell and not in the intestines, so once the virus has mutated, it is no longer shed in the feces.

Two Forms of FIP

  • Wet (effusive): The wet form of FIP results in fluid accumulation in body cavities such as the abdomen and chest, causing 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 the organ most affected by disease.

Signs & Symptoms

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

  • Loss of appetite
  • Weight loss
  • Lethargy
  • Fluctuating fever that is not responsive to antibiotics

How Can I Prevent My Cat from Getting FIP?

  • Prevention of FIP is difficult since there are many factors contributing to development of the disease.
  • Research has shown that some cats have a genetic predisposition which causes them to be more susceptible to developing FIP. Therefore, although the FIPV itself is not contagious, multiple cats within the same family may be affected.
  • Selective breeding for overall disease resistance and health, along with stress reduction, is likely beneficial.
  • Ensure you keep your cat healthy by visiting your veterinarian for regular wellness examinations.
  • Minimize exposure to infectious diseases and keep your cat up to date on recommended vaccinations.
  • Litter boxes should be cleaned daily and located away from food and water dishes.


  • To date, there is no test to screen healthy cats for the risk of developing FIP.
  • In order to diagnose FIP in a sick cat, veterinarians must piece together several diagnostic clues, including clinical signs and common findings on lab work that correlate with FIP, as well as ruling out other diseases. Analysis of any fluid in the abdomen or chest is helpful for accurate diagnosis.

Vaccination for FIP?

While a vaccine was developed to prevent FIP in cats, it has been controversial and there is limited evidence to show its effectiveness. Therefore, it is not recommended to be given at this time.


There are no known effective treatments for cats with FIP, but supportive care may help keep the affected cat comfortable and pain free. Currently, several veterinary research groups are working on novel approaches to treat the disease, meaning that in the future a treatment may become available.