Cat Feline Infectious Peritonitis Management

Feline infectious peritonitis (FIP) was once a universally fatal disease in cats — but antiviral treatment has transformed it into a manageable, often curable condition, revolutionizing welfare outcomes.

Key Facts

FIP is caused by a mutated form of feline coronavirus (FCoV) that causes fatal systemic inflammation
FIP was until recently invariably fatal, with survival measured in weeks to months after diagnosis
GS-441524, a nucleoside analogue antiviral, achieved cure rates of over 80% in clinical trials when administered for 12 weeks
GS-441524 was initially available only through grey market sources in Asia; licensed formulations (e.g., Enjanta) are now approved in several countries
FIP occurs in two clinical forms: wet (effusive) with fluid accumulation and dry (non-effusive) with granulomas in organs
Young cats under 3 years and older cats over 10 are most susceptible; multi-cat households have elevated risk
Neurological FIP — affecting the brain and spinal cord — requires higher GS-441524 doses and has good outcomes with adequate treatment

Welfare Considerations

The transformation of FIP from invariably fatal to largely curable represents one of the most significant feline welfare advances of the past decade. Before antiviral treatment, a FIP diagnosis meant watching a young cat deteriorate over weeks — progressive weight loss, fluid accumulation, fever, and eventual death. The discovery and advocacy around GS-441524 (driven in significant part by owner communities and veterinary researchers before regulatory approval) gave thousands of cats a chance at full recovery. Access remains the primary welfare challenge: licensed formulations are now available in many markets, but cost and availability barriers persist. Ensuring owners receive accurate, current information about treatment options — and that vets are familiar with dosing protocols — is essential to realizing the full welfare benefit of this breakthrough.

What You Can Do

If your cat is diagnosed with FIP, seek immediate referral to a veterinary internist familiar with current antiviral protocols
Ask specifically about GS-441524 (Enjanta or equivalent) — some veterinarians may not yet be current on treatment options
Connect with the FIP Warriors Facebook group for peer support, treatment guidance, and access information
Support advocacy organizations pushing for affordable, licensed antiviral access globally
Test multi-cat households for FCoV exposure — while not predictive of FIP development, it identifies high-risk environments