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 rule out blood-related conditions
- Electrolyte tests to ensure your cat isn’t dehydrated or suffering from an electrolyte imbalance
- A feline leukemia virus (FeLV) test
- A feline immunodeficiency virus (FIV) test
- Cardiac tests to rule out heart-related issues
- A Feline Coronavirus titer to determine the presence of antibodies against coronavirus
- An FIP Virus PCR test to confirm the presence of the virus and to check whether the coronavirus is carrying the mutations associated with FIP
Unfortunately, there is no cure for FIP; the severity of the infection will determine the treatment, which is limited to supportive care based on symptoms. Treatment may include the administration of fluids to treat dehydration, antibiotics to treat secondary infections, procedures to remove excess fluid from the chest/abdomen, the use of anti-inflammatory drugs called glucocorticoids, and nutritional support. Additional treatment may be suggested based on your cat’s condition.
The best way to protect your cat from this often fatal disease is to keep clean her living area, food and water bowls, and litter box. Keeping your cat strictly indoors reduces her risk of exposure to strange and potentially infected cats.
If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.