Feline infectious peritonitis (FIP) was until recently a uniformly fatal disease causing enormous suffering in cats, but antiviral treatments are transforming outcomes.
FIP caused profound welfare suffering: cats typically experienced weeks of progressive illness — fluid accumulation, organ failure, neurological symptoms — before death. For owners, the combination of rapid progression, young age of affected cats, and absence of treatment made FIP one of the most distressing diagnoses in feline medicine. The emergence of curative antivirals represents an extraordinary welfare advance, transforming a death sentence into a treatable condition for most affected cats.