Feline infectious peritonitis (FIP) was until recently universally fatal after diagnosis, but antiviral treatments have transformed it into a manageable condition, representing a major welfare advance.
FIP historically caused profound suffering in affected cats — the disease progresses relentlessly from diagnosis to death, during which cats experience severe dyspnea from effusions, neurological signs from CNS involvement, ocular pain from uveitis, and the systemic malaise of progressive organ failure. Families faced the welfare burden of watching a cat die from an untreatable disease over days to weeks after diagnosis. The development of effective antiviral treatments represents one of the most dramatic welfare improvements in feline medicine in decades: a disease category that was an automatic death sentence became a treatable condition with remission achievable in the majority of cases. The remaining welfare challenge is access — treatment courses cost hundreds to thousands of dollars depending on the formulation and cat size, creating an economic barrier to welfare benefit.