Signs and Diagnosis of FIP

Coronavirus infection usually has no signs. In some cases, however, signs can include the following:

This stage may last several days or months if severe.

The signs of feline infectious peritonitis vary depending on which organs are involved. Many organs, including the liver, kidneys, pancreas, CNS, and eyes, can be affected. The length of time between infection and mutation of the virus and development of signs varies between cats. Affected cats may be alert or depressed. Some eat with a normal or even increased appetite; others refuse to eat. Fever, weight loss, and/or jaundice may be noted.

Some cats have noticeable fluid build-up in the abdomen causing it to look distended. About one-third of cats with effusive disease have lung involvement and difficulty breathing. Fluid may also accumulate around the heart.

Cats without obvious fluid build-up usually have a history of vague illness. This includes repeated fever, malaise, weight loss, and occasionally organ failure (most often the kidneys or liver).

Involvement of the eyes and central nervous system is common and may occur either simultaneously or independently of other signs. When the eyes are affected, there may be bleeding or accumulation of pus in one or both eyes. Other ocular changes, including blindness, can also occur. The most common sign of nervous system involvement is poor coordination of muscles with slight paralysis progressing to generalized failure of muscle coordination. Convulsions (seizures), tremors, personality changes, and increased sensitivity to touch may also be seen.

Your veterinarian can diagnose feline infectious peritonitis based on the cat’s medical history, signs found during a physical examination, and results of laboratory tests. Ultrasonography or surgical biopsies may also be necessary. The diagnosis can be challenging to make, especially in cats without fluid build-up, and may require a combination of multiple types of tests.