Feline infectious peritonitis is caused by a strain of virus called feline coronavirus. Most strains of this virus are avirulent and can be countered by the cat’s immune system. However, some mutant strains of this virus can give rise to a condition known as feline infectious peritonitis.

The virus enters the white blood cells and circulates throughout the body triggering severe inflammatory reaction in the areas where the white blood cells are localized. Inflammation can occur in organs like liver, abdomen and kidney. This disease progresses rapidly and is almost always fatal. The virus spreads through contact with infected cats and can also pass from an infected cat to its kitten. Cats with weak immune systems and very young cats below 2 years of age are more prone to this virus than other healthy cats.

Feline infectious peritonitis is a rare disease and is seen more commonly among stray cats, cats which live in shelters and catteries and in households with multiple cats. There are two forms f feline infectious peritonitis. The dry form is characterized by inflammation in the internal organs. The wet form is characterized by the buildup of fluid in the abdomen, chest and body cavities. Cats which have FeLV infection are more likely to contract feline infectious peritonitis.