Feline infectious peritonitis is a viral disease that can affect any organ in the body, and it is caused by the feline coronavirus. In publishing these Guidelines, the AAFP and EveryCat aim to provide veterinarians with the essential information necessary to provide a FIP diagnosis in cats including characteristics and pathogenesis of FIP, as well as numerous diagnostic testing factors to understand when testing for FIP.
Source: EveryCat Health Foundation, August 31, 2022. Link. Since FIP is fatal when untreated and nearly every small animal veterinary practitioner will see FIP cases, the ability to obtain a correct diagnosis is critical. FIP especially affects young cats less than two years old. It can be challenging to diagnose in some cases and is often considered an enigma by the veterinary profession.