Clinical and Hematologic Response to Remdesivir Treatment in Cats With Feline Infectious Peritonitis in Iran: A Prospective Observational Study

Introduction: Feline infectious peritonitis (FIP) is a progressive and often fatal disease caused by virulent feline coronavirus (FCoV) mutations. Despite the increasing use of antiviral agents such as remdesivir, prospective clinical data from Iran remain limited. This prospective observational study evaluated clinical and hematological responses to remdesivir in ۳۱ polymerase chain reaction (PCR)-confirmed FIP cases.Materials & Methods: Sixteen cats (۵۱.۶%) had the effusive form, nine (۲۹%) the non-effusive form, and six (۱۹.۴%) exhibited ocular or neurologic involvement. All cats received remdesivir following a standardized ۸۴-day protocol which consisted of a ۴-day induction phase (۱۰ mg/kg daily for effusive FIP and ۱۵ mg/kg daily for non-effusive/neurologic forms), followed by once-daily subcutaneous maintenance therapy from day ۵ to day ۸۴. Clinical and laboratory evaluations were performed on days ۰, ۴۲, and ۸۴. Results: Significant clinical improvement occurred over the treatment period, with anorexia decreasing from ۶۴.۵% to ۶.۵%, weight loss from ۸۳.۹% to ۱۹.۴%, and lethargy from ۶۷.۷% to ۲۵.۸%, while dyspnea, abdominal distension, and icterus resolved completely (P<۰.۰۵). The mean clinical severity score demonstrated a marked reduction, decreasing from ۶.۴۰±۱.۲۰ at baseline to ۱.۵۵±۰.۹ at day ۸۴ (P<۰.۰۰۱), indicating a pronounced overall clinical improvement. Hematological abnormalities characteristic of FIP also improved significantly. Hemoglobin increased from ۷.۷۲±۱.۵۷ to ۹.۷۵±۱.۱۸ g/dL and hematocrit from ۲۸.۲۸±۵.۹۱% to ۳۶.۷±۴.۵۷%, while total leukocytes decreased from ۱۳.۷۷±۵.۰۹×۱۰³/µL to ۷.۳۱±۲.۱۸×۱۰³/µL (P<۰.۰۵). Lymphocyte count increased (from ۱.۳۸±۰.۹۶ to ۲.۵۶±۰.۸۸×۱۰³/µL) while neutrophils decreased (from ۱۰.۱۸±۲.۹ to ۴.۰۲±۱.۳۱×۱۰³/µL), thereby lowering the neutrophil-to-lymphocyte ratio from ۱۰.۵۳±۶.۸۲ to ۱.۹۸±۱.۴۶ (P<۰.۰۰۱). Mid-treatment data (day ۴۲) demonstrated early hematological recovery. Conclusion: These findings suggest that remdesivir induces marked and consistent clinical improvement and substantial hematologic normalization in naturally occurring FIP in Iran, providing region-specific evidence supporting its efficacy.

کلیدواژه ها:

Clinical improvement ، Feline coronavirus (FCoV) ، Hematology ، Molecular diagnosis ، Remdesivir