Feline infectious peritonitis (FIP) was once invariably fatal. New antiviral treatments have transformed outcomes, offering welfare recovery to thousands of affected cats each year.
FIP's transformation from a uniformly fatal diagnosis to a treatable condition represents one of the most significant welfare advances in feline medicine in recent years. Before antiviral treatments became available, diagnosis of FIP meant palliative care and euthanasia. The development and rollout of GS-441524 — initially accessible only through gray market channels as Gilead Sciences did not license it for veterinary use — changed this entirely. Cats with wet FIP, previously deteriorating within days, now achieve remission within weeks of starting treatment. Welfare considerations during treatment include the stress of daily medication administration and monitoring visits. Relapse is possible and requires retreatment. Access to treatment remains unequal globally, with cost a significant barrier for many owners.