RISK OF FELINE INFECTIOUS PERITONITIS IN CATS NATURALLY INFECTED WITHFELINE CORONAVIRUS

A longitudinal survey of 820 cats in 73 households was conducted over a period of 6 years to establish the fate of pet cats that were seropo sitive after natural exposure to feline coronavirus (FCoV). In particu lar, their risk of developing feline infectious peritonitis (FIP) was determined. The seropositive cats were assigned to 1 of 3 groups: cats from households in which FIP had recently been diagnosed; cats from h ouseholds in which FIP had not been diagnosed, but from which kittens had been relocated and subsequently died of FIP; and cats from househo lds in which FIP had not been diagnosed. Cats in the first group were not at greater risk of developing FIP than were cats in the other 2 gr oups. Consequently, any household in which seropositive cats live must be considered a potential source of FCoV that can cause FIP. There wa s no evidence, that the enhanced disease, which has been described aft er experimentally induced infection of seropositive cats, exists in na ture. Thus, analysis of the survival of the seropositive cats over per iods of up to 36 months indicated that their risk of developing FLP de creased with time, suggesting the development of immunity rather than increased susceptibility to disease. In addition, of 56 cats deemed to have been naturally reinfected because their anti-FCoV antibody titer s decreased and subsequently increased, only 3 developed np.