Two Cases of Feline Infectious Peritonitis Treated with Molnupiravir

Abstract

We experienced two cases of feline infectious peritonitis (FIP) that were treated with molnupiravir for a short period. Case 1 was a 5-year-old neutered male feline Scottish Fold, presenting to our hospital with decreased vigor, appetite, and abdominal distention. FIP virus was detected in the ascites fluid, and FIP was diagnosed. Molnupilavir (10 mg/kg BID) and prednisolone (1 mg/kg SID) were administered. On day 4, appetite and vigor recovered, ascites disappeared on day 18, and blood tests normalized; therefore, the medication was stopped. Case 2 was a 10-month-old neutered male Scottish Fold cat, diagnosed with FIP at another hospital and visited our hospital for a second opinion. The FIP virus was detected in the ascites fluid, and FIP was diagnosed. Molnupilavir (10 mg/kg BID) and prednisolone (1 mg/kg SID) were administered. On day 5, appetite and vigor recovered, ascites disappeared on day 14, and blood tests normalized on day 34; therefore, the medication was discontinued. The patients had no recurrence. Molnupiravir could be cured despite the drug was stopped if the clinical symptoms disappeared.