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Feline Infectious Peritonitis (FIP)

Reviewed by Dr. Alexis Seguin, DVM, MS, DACVIM on Thursday, April 2, 2015
Posted December 20, 2011 in Cat Diseases & Conditions A-Z

Feline Infectious Peritonitis (FIP) is a progressive and often fatal disease that is caused by a coronavirus. In most cases, a coronavirus causes mild, treatable symptoms (respiratory and/or gastroenteritis) in cats. In rare cases, the coronavirus may mutate to a more virulent form which is able to weaken the cat’s immune system and spread throughout the body by way of the white blood cells, often resulting in death. Kittens and cats under the age of 3 are at greatest risk for FIP. As cats mature and their immune systems strengthen, their risk is reduced.

Kittens and young cats are at highest risk for infection. Cats with weakened immune systems, such as those infected with feline leukemia or feline immunodeficiency virus, are also at risk. Cats in multiple-cat households and catteries are also at a higher risk. Not all cats exposed to FIP will develop the disease; the majority of cats exposed to it will not get sick. FIP is thought to spread through feces; the virus can stay active for a long period of time, until surfaces are thoroughly disinfected.

There are two forms of FIP. An acute form, often referred to as “wet” FIP and a chronic form, known as “dry” FIP. The acute or “wet” form comes on suddenly, and its most common sign is a buildup of fluid in the abdomen and chest cavity, causing difficulty in breathing and, in some cases, a swollen abdomen. With the chronic or “dry” form, there is no fluid buildup; instead, lesions develop on the organs, often resulting in neurological symptoms such as seizures or paralysis. Liver and kidney problems may also occur. Most often, you will notice weight loss and your cat will seem depressed. Most cats that become infected get the acute form of FIP.

Unfortunately FIP is difficult to definitively diagnose. Blood tests exist to determine if your cat has been exposed to feline coronavirus, but with the exception of PCR, are not specific to FIP. Your veterinarian will examine your cat and take a thorough history of her activities. Based on her symptoms, the following tests may be recommended by your veterinarian:

  • Chest/abdominal x-rays to determine if there is fluid buildup in the abdomen/chest
  • A microscopic examination of the fluid extracted from the abdomen/chest
  • Chemistry tests to evaluate kidney, liver, and pancreatic function, as well as sugar levels
  • A complete blood count (CBC) to

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