Feline infectious peritonitis (FIP) was once virtually always fatal. Antiviral treatments have transformed outcomes, making welfare-focused treatment a realistic option for affected cats.
FIP treatment represents one of the most dramatic welfare improvements in recent feline medicine. Until antiviral treatment became available (initially through gray-market access, increasingly through licensed products), an FIP diagnosis meant near-certain death within weeks. Affected cats experience progressive abdominal fluid accumulation, fever, weight loss, and in neurological forms, seizures and disorientation — a prolonged, suffering-filled decline. Antiviral treatment with GS-441524-based compounds reverses these signs in the majority of cats within days to weeks. Treatment requires commitment: 84 days of daily injections or oral dosing, which some cats tolerate poorly, plus follow-up monitoring. Cost remains a significant barrier for many owners. However, for cats that receive full treatment, survival with good quality of life is now the expected outcome rather than the extraordinary exception. Advocacy for affordable, licensed treatment access is the remaining welfare challenge.