FIP was previously almost universally fatal in cats; antiviral treatments including GS-441524 have transformed it into a manageable condition, dramatically improving welfare outcomes.
The transformation of FIP from a universally fatal disease to a manageable condition with good prognosis represents one of the most dramatic welfare improvements in companion animal medicine in recent years. Previously, cats diagnosed with FIP faced euthanasia as the only humane option after rapid deterioration. GS-441524 and related nucleoside antivirals achieve sustained remission in the majority of treated cats, converting a diagnosis that meant certain death into one that means a period of intensive treatment followed by return to normal health. Access to treatment has been uneven due to licensing complexities, but the welfare case for making effective treatment universally accessible is clear.