02/11/2026
What is FIP in cats?
Feline infectious peritonitis (FIP) is a viral disease of cats caused by certain strains of a virus called the feline coronavirus. Most strains of feline coronavirus are found in the gastrointestinal tract and do not cause significant disease. These are referred to as feline enteric coronavirus (FeCV). Cats infected with FeCV usually do not show any symptoms during the initial viral infection, but may occasionally experience brief bouts of diarrhea and/or mild upper respiratory signs from which they recover spontaneously. FeCV-infected cats usually mount an immune response through which antibodies against the virus are produced within 7-10 days of infection. In approximately 10 percent of cats infected with FeCV, one or more mutations of the virus can alter its biological behavior, resulting in white blood cells becoming infected with virus and spreading it throughout the cat’s body. When this occurs, the virus is referred to as the FIPV. An intense inflammatory reaction to FIPV occurs around vessels in the tissues where these infected cells locate, often in the abdomen, kidney, or brain. It is this interaction between the body’s own immune system and the virus that is responsible for the development of FIP.
FIP generally occurs in one of two forms, a “wet form” in which fluid accumulates in body cavities like the abdomen and/or chest, and a “dry form” that affects the central nervous system, resulting in neurologic signs. Once a cat develops clinical FIP, the disease is usually progressive and almost always fatal without therapy that has been available in countries Australia and the UK for several years and has recently become available as an oral compounded formulation in the US. This newly available compounded formulation requires a veterinary prescription. The availability of safe and effective therapies for FIP represents a dramatic advancement in veterinary medicine, and we recommend that you consult with your veterinary professional team if you have questions about acquiring FIP therapy for a cat suffering from this dreadful disease. To our knowledge, coronaviruses cannot be passed from infected cats to humans.
