Feline infectious peritonitis was historically almost universally fatal. Antiviral treatments have transformed outcomes for affected cats, representing one of veterinary medicine's most significant recent welfare advances.
FIP caused profound welfare harm for decades as a disease that primarily struck young cats with a distressing and inevitably fatal course. The development of effective antiviral treatment represents one of the most significant recent advances in feline welfare, transforming a death sentence into a curable condition for most affected cats. The welfare challenge now is ensuring access to treatment: GS-441524 is not licensed in many countries, requiring owners to obtain it through unofficial channels at significant cost, or to euthanise cats that could be saved. Advocacy for regulatory licensing of GS-441524 through appropriate approval pathways would improve access and reduce the welfare harm of treatable cats dying due to cost or access barriers.