Epidemiological and Clinical Insights from 68 Veterinarian-Reported Cases of Feline Infectious Peritonitis During the Documented 2023 FIP Epizootic in Cyprus

In 2023, Cyprus experienced a large-scale epizootic of feline infectious peritonitis (FIP) associated with a novel feline coronavirus, FCoV-23. While molecular investigations have elucidated its recombinant origin, field-based clinical and epidemiological data remain limited. A prospective study used a structured 30-item questionnaire embedded in veterinary management software to characterize FIP cases. Data were voluntarily submitted by registered veterinarians across Cyprus for cases identified between late 2022 and 2025. Data from 68 cases reported by 22 clinics (response rate 21.0%) were analyzed. Affected cats were older than typically reported for FIP (mean age of 3.9 years; median = 3.0; range 0.4y - 12.9y, SD = 3.41), with most cases documented from Limassol (51.5%) and Nicosia (25.0%). The most frequently reported clinical signs were anorexia (60.3%) and weight loss (54.4%), while neurological involvement was documented in 35.3% of cases. An albumin-to-globulin ratio <0.8 was observed in 86.8% of cats tested. Antiviral (GS-441524 or molnupiravir) therapy was administered in 92.2% of cases, with reported clinical improvement in 88.9%. These findings demonstrate the value of questionnaire-based reporting for documenting outbreak-associated disease patterns and confirm the change in viral tropism seen in FCoV-23 infection as an increased prevalence of neurological cases compared to ‘traditional’ FIP.