Cat Feline Infectious Peritonitis: Managing a Formerly Fatal Disease

Feline infectious peritonitis was until recently universally fatal, but antiviral treatments developed since 2019 are transforming outcomes for affected cats with a welfare revolution in progress.

Key Facts

FIP is caused by mutation of feline coronavirus into a virulent systemic form affecting macrophages
FIP historically killed virtually all affected cats within weeks to months of diagnosis
Antiviral drugs including GS-441524 and molnupiravir achieve remission in over 80% of treated cats
Treatment requires daily administration for 84 days followed by a monitoring period
Costs of treatment remain high — often thousands of dollars — limiting access for many owners
Regulatory approval for veterinary use of antivirals is advancing in some countries, improving access

Welfare Considerations

FIP treatment represents one of veterinary medicine's most dramatic welfare transformations in recent decades. Cats that would previously have died in weeks — often after prolonged suffering from effusions, neurological signs and systemic disease — can now achieve sustained remission with antiviral treatment. The welfare revolution is ongoing but unequal — high treatment costs mean some cats cannot access life-saving treatment. Advocacy for affordable veterinary antiviral access and regulatory approval is both a welfare and an equity concern for cat owners.

What You Can Do

Consult a veterinary specialist immediately if your cat is diagnosed with FIP — treatment is now available
Research antiviral treatment options including GS-441524 through specialist veterinary oncologists
Support organisations working on affordable FIP treatment access for lower-income cat owners
Advocate for regulatory approval of FIP antivirals to improve accessibility and affordability
Share information about FIP treatment advances with other cat owners — many remain unaware it is treatable