Feline infectious peritonitis

Feline infectious peritonitis (FIP) is a fatal, incurable disease that affects cats. It is caused by Feline Infectious Peritonitis Virus (FIPV), which is a mutation of Feline Enteric Coronavirus (FECV) - (Feline coronavirus FCoV). Experts do not agree on the specifics of genetic changes that produce the FIPV. The mutated virus has the ability to invade and grow in certain white blood cells, namely macrophages. The immune system's response causes an intense inflammatory reaction in the containing tissues. This disease is generally fatal. However, its incidence rate is roughly 1 in 5,000 for households with one or two cats. A nasally administered vaccine for FIP is available but controversial, and it is not proven to be highly effective. An experimental polyprenyl immunostimulant is being manufactured by Sass and Sass and tested by Dr. Al Legendre, who described survival over 1 year in three cats diagnosed with FIP and treated with the medicine. In one case study, a female cat diagnosed with dry FIP has survived 26 months from the date of definitive diagnosis.

FECV is very common, especially in places where large groups of cats are kept together (animal shelters, catteries, etc.). Cats become infected by inhaling or ingesting the virus. The most commonly cited transmission source is feces, although contaminated surfaces such as food dishes and clothing can transmit the virus as well.

Despite the prevalence of FECV, most infected cats do not develop FIP. Often, exposure to FECV produces no clinical signs, but may cause a mild diarrhea. Therefore, a cat without clinical signs may still be an FECV carrier and may pass the virus to another cat. In any cat infected with FECV there is a chance that the virus may mutate into the FIP-causing form. This chance is increased for cats that are immune compromised, including very young and very old cats. There is also thought to be a genetic component to susceptibility to viral mutation.

There are two main forms of FIP: effusive (wet) and non-effusive (dry). While both types are fatal, the effusive form is more common (60-70% of all cases are wet) and progresses more rapidly than the non-effusive form.

The hallmark clinical sign of effusive FIP is the accumulation of fluid within the abdomen or chest, which can cause breathing difficulties. Other symptoms include lack of appetite, fever, weight loss, jaundice, and diarrhea.

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