Risk factors for feline infectious peritonitis among cats in multiple-cat environments with endemic feline enteric coronavirus

OBJECTIVE: To determine what risk factors, other than genetic predisposition, contribute to the incidence of feline infectious peritonitis (FIP) in private breeding catteries and animal shelters. DESIGN: Cats from 7 catteries and a shelter were observed monthly for 1 year. At each visit, cats were examined, fecal samples were collected for determination of feline coronavirus shedding, and blood samples were collected for determination of coronavirus antibody titers. Diagnostic tests were performed on all cats that died of FIP. ANIMALS: 275 purebred or random-bred cats that were kept by private breeder-owners in homes. RESULTS: 24 cats died of FIP during the study. Development of FIP was not associated with cattery, mean cat number, mean age, sex, cattery median coronavirus antibody titer, husbandry and quarantine practices, caging and breeding practices, or prevalence of concurrent diseases. However, risk factors for FIP included individual cat age individual cat coronavirus titer, overall frequency of fecal coronarvirus shedding, and the proportion of cats in the cattery that were chronic coronavirus shedders. Deaths from FIP were more frequent in fall and winter, and on the basis of analysis of cattery records, the number of deaths varied yearly. Epidemics (> 10% mortality rate) were reported at least once in 5 years in 4 catteries. CLINICAL IMPLICATIONS: Elimination of FIP from a cattery is only possible by total elimination of endemic feline enteric coronavirus (FECV) infection. The most important procedure to reduce FECV from catteries is elimination of chronic FECV shedders.