Abstract
Feline infectious peritonitis (FIP) is a fatal but now treatable disease in cats caused by feline coronavirus (FCoV). This study prospectively investigated viral coinfections in 100 cats diagnosed with FIP and subsequently treated with oral GS-441524 (Bova UK) and their influence on outcome, focusing on viruses potentially associated with feline chronic gingivostomatitis (FCGS). Cats were tested for feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline calicivirus (FCV), feline herpesvirus (FHV), feline foamy virus (FFV), and feline gammaherpesvirus (FcaGHV1). Coinfections were identified at the following frequencies: FCV (27), FFV (22), FHV (6), FIV (4), FcaGHV1 (2), and FeLV (2, both progressive infections). FFV infection was significantly associated with FIV (p(F) = 0.0021) and FHV (p(F) = 0.0226) infection. FCGS was present in 25/97 cats with FCV infection being associated with FCGS (pF = 0.0032); no significant associa-tions were found for the other viruses and FCGS. The 42-day oral GS-441524 treatment's success rate was 94% (five cats died, one relapsed). Coinfections did not significantly influence disease severity or treatment outcome, although the low number of cases for some pathogens warrants further investigation. However, advanced age was associated with treatment failure, potentially due to delayed diagnosis as FIP is considered to be less common in older individuals, or to age-related changes in immune function. In summary, viral coinfections, particularly with FCV, were common and should be considered in the clinical and hygienic management of cats with FIP.