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Cat FIP (Feline Infectious Peritonitis)

The following information isn't intended to replace regular visits to your veterinarian. If you think your cat may have feline infectious peritonitis, please see your veterinarian immediately. And remember, please do not give any medication to your pet without talking to your veterinarian first.

What Is Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) is a viral disease that occurs worldwide in wild and domestic cats. It is caused by a type of virus called a coronavirus, which tends to attack the cells of the intestinal wall. In 1970, the coronavirus that causes FIP was isolated and characterized. In 1981, another coronavirus was isolated. Although this virus is nearly identical to the FIP virus, cats who were infected with it developed only very mild diarrhea and recovered easily.

What Are the Symptoms of FIP?

FIP manifests in a “wet” form and a “dry” form. Signs of both forms include fever that doesn't respond to antibiotics, anorexia, weight loss and lethargy. In addition, the wet form of FIP is characterized by accumulation of fluid in the abdominal cavity, the chest cavity, or both. Cats with fluid in the chest exhibit labored breathing. Cats with fluid in the abdomen show progressive, nonpainful abdominal distension. In the dry form of FIP, small accumulations of inflammatory cells, or granulomas, form in various organs, and clinical signs depend on which organ is affected. If the kidneys are affected, excessive thirst and urination, vomiting and weight loss are seen; if the liver, jaundice. The eyes and the neurologic system are frequently affected, as well.

How Is FIP Diagnosed?

Diagnosing FIP is challenging. Despite the claims made by some laboratories and test manufacturers, there is currently no test that can distinguish between the harmless intestinal coronavirus and the deadly FIP coronavirus. A positive test may support the veterinarian's suspicions, but by itself is inconclusive. It means only that a cat has been exposed to and may be harboring a coronavirus. A negative test usually (but not always) indicates that the cat is unlikely to have FIP.

If a cat has what appears to be the wet form of the disease, laboratory analysis of some of the fluid can support a diagnosis of FIP. A 1994 study reported that cats with signs suggestive of FIP, who also had a high coronavirus antibody level, reduced numbers of lymphocytes and high levels of globulins in the bloodstream, had an 88.9 percent probability of having FIP. Diagnosing the dry form of the disease is even more challenging, often requiring biopsy of affected organs.