Understanding FIP
Feline Infectious Peritonitis.
Moo was diagnosed in early 2025. Modern treatment exists. Here's what you need to know.
FIP is caused by a coronavirus mutation. It was long considered universally fatal — but FDA-approved antiviral treatment has changed what's possible. Every caregiver deserves to know this.
The basics
What is FIP?
FIP — Feline Infectious Peritonitis — is a serious, progressive disease caused by a mutation of the Feline Enteric Coronavirus (FCoV). Most cats carry the underlying coronavirus harmlessly. In some cats, it mutates into a form that infects white blood cells and spreads through the body — triggering widespread inflammation that damages blood vessels and major organs.
FIP was historically considered universally fatal. That changed. As of 2024, an FDA-approved antiviral treatment (GS-441524, brand name Kitten Lifesaver) can cure FIP — but it requires 84 days of intensive medication and costs thousands of dollars. Nine Lives for All exists to help close that gap.
- Any cat of any age can develop FIP
- Young cats (under 3 years) and seniors are most at risk
- Maine Coons and other purebreds have higher incidence
- FIP is not contagious between cats
- Modern treatment (GS-441524) can cure FIP
Quick facts
Know the signs
Four forms of FIP.
FIP can present in multiple ways. Knowing which form you're dealing with affects how quickly symptoms develop and which diagnostic tests are most useful.
Wet FIP
The most common and fastest-progressing form. Fluid accumulates in the abdomen or chest cavity, causing a distended belly or breathing difficulty. Symptoms escalate quickly.
Dry FIP
No fluid buildup, but granulomas (inflammatory lesions) form on organs. Slower to progress than wet FIP. Symptoms are subtler — weight loss, lethargy, fever that doesn't respond to antibiotics.
Ocular FIP
Inflammation affects the eyes — uveitis, cloudiness, or color changes in the iris. Can occur alone or alongside dry/wet FIP. Eye changes can appear suddenly.
Neurological FIP
Inflammation affects the brain and spinal cord. Symptoms include seizures, loss of coordination, behavioral changes, and paralysis. This form requires urgent attention.
Common signs
Symptoms to watch for.
FIP symptoms are often nonspecific early on. If your cat has several of these — especially with a persistent fever — contact a vet and mention FIP specifically.
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Persistent feverDoesn't respond to antibiotics; comes and goes
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Distended abdomenPot-belly appearance from fluid accumulation (wet FIP)
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Lethargy & weaknessSudden drop in energy and interest in activity
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Weight & appetite lossProgressive wasting despite treatment
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Eye changesCloudiness, color change, or inflammation (ocular FIP)
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Neurological signsSeizures, loss of balance, hind leg weakness
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Breathing difficultyLabored or rapid breathing from chest fluid
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JaundiceYellowing of gums, skin, or whites of the eyes
This is not a substitute for veterinary care. If your cat is showing these symptoms, contact a veterinarian immediately and specifically ask about FIP testing. Early diagnosis significantly improves outcomes.
Modern treatment
FIP can now be cured.
Treatment that was unavailable just years ago is now FDA-approved. The 84-day protocol is intensive — but it works.
GS-441524 (Kitten Lifesaver)
The primary antiviral treatment for FIP. Requires 84 days of daily injections or oral dosing. ~90% remission rate when completed fully. Brand names include Bova Kitten Lifesaver and Mutian.
84-Day Treatment Protocol
Treatment is administered daily for a minimum of 84 days, followed by a 12-week observation period. Dosage depends on FIP form, weight, and severity. Neurological and ocular forms often require higher doses.
Nine Lives for All Assistance
The full 84-day treatment can cost $3,000–$8,000+. Nine Lives for All exists to help cover this cost for families who can't afford it. Submit a request to start the intake process.
Trusted sources
Where to go for help.
Community Organization
SOCK FIP
Devoted to saving cats from FIP. Offers education, community support, and connects families with treatment resources. One of the most active FIP communities online.
sockfip.org →Academic / Veterinary
Cornell Feline Health Center
Comprehensive, peer-reviewed information on FIP from Cornell University's College of Veterinary Medicine. Essential reading for caregivers and clinicians.
vet.cornell.edu →Diagnostic Laboratory
UC Davis VGL — FIP Testing
UC Davis Veterinary Genetics Laboratory offers diagnostic testing services, including the real-time RT-PCR test used to detect FIP mutations in effusion fluid and tissues.
vgl.ucdavis.edu →Support Community
FIP Warriors 5b
A large, active Facebook community of caregivers, veterinarians, and survivors sharing treatment experiences, dosing guidance, and emotional support throughout the 84-day journey.
FIP Warriors on Facebook →Common questions
FAQ
FIP diagnosis typically involves a combination of:
- Clinical signs — symptoms consistent with FIP
- Blood work — elevated globulins, low albumin:globulin ratio, elevated bilirubin
- Effusion analysis — characteristic "straw-colored" fluid with high protein in wet FIP
- PCR testing — detecting FCoV mutations in fluid or tissue samples
- Immunostaining — most definitive, from biopsy or necropsy tissue
No single test is 100% definitive. Work with a veterinarian experienced in FIP for the best diagnostic pathway.