CATS · Condition guide
Feline infectious peritonitis (FIP): real veterinary cases
Feline infectious peritonitis was once a guaranteed death sentence — a fatal immune-mediated disease triggered when an ordinary feline coronavirus mutates inside the cat and the immune system responds catastrophically. The "wet" (effusive) form fills the abdomen or chest with thick, straw-coloured fluid; the "dry" (non-effusive) form causes granulomatous lesions in the eyes, brain, kidneys, or liver. Young cats (under 2) and cats from multi-cat environments are most at risk.
The landscape changed dramatically in 2019 when GS-441524 proved curative in the vast majority of cases. Legally accessible antiviral treatment is now available in many countries and published cure rates exceed 80-90% for the effusive form. FIP has gone from uniformly fatal to genuinely treatable — one of the biggest recent advances in feline medicine.
What vets typically check for
- Fluid analysis (if effusive): high protein, low cellularity, positive Rivalta test.
- Bloodwork: hyperglobulinemia, low albumin:globulin ratio, elevated bilirubin.
- Coronavirus titre + immunofluorescence or RT-PCR on fluid/tissue for confirmation.
- Ocular exam + neurological exam — dry FIP frequently involves the eyes (uveitis) or CNS.
- Treatment: GS-441524 antiviral for 84 days (12 weeks); monitoring with bloodwork every 2-4 weeks.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Feline infectious peritonitis (FIP). Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- EXPRESS: Low incidence of feline infectious peritonitis in rehomed shelter cats with known feline coronavirus status: a cohort study of 767 cats.
Journal of feline medicine and surgery · 2026 · Australia
A group of shelter cats in Sydney, Australia, were tested for feline coronavirus (FCoV) shortly after adoption to see if it affected their long-term health. Out of 767 cats, only two were diagnosed with feline infectious peritonitis (FIP) years later, which is a very low rate. Many of the cats did experience vomiting and diarrhea, but these symptoms were not linked to FCoV infe
- VV116 exerts potent efficacy against feline infectious peritonitis.
Veterinary microbiology · 2026 · China
A group of cats with feline infectious peritonitis (FIP), a serious viral disease, were treated with a new antiviral medication called VV116. This treatment significantly improved their health, with 75% of the cats surviving and showing reduced levels of the virus in their bodies. Additionally, the cats displayed noticeable improvements in their overall condition. These results
- EXPRESS: Multiplex Fluorescent Immunocytochemistry is a Complementary Test for the Diagnosis of Feline Infectious Peritonitis: A Diagnostic Clinical Trial.
Journal of feline medicine and surgery · 2026 · United States
A group of cats showing signs of feline infectious peritonitis (FIP), a serious viral disease, were tested using a new method called multiplex fluorescent immunocytochemistry (MF-ICC) to see how well it could diagnose the condition. The study included 84 cats, with 58 diagnosed with FIP and 26 as controls. MF-ICC showed a good level of accuracy, being more sensitive in analyzin
- Unlicensed antiviral treatment with GS-441524: How are clinicians approaching feline infectious peritonitis in primary care practices?
Schweizer Archiv fur Tierheilkunde · 2026
A group of cats diagnosed with feline infectious peritonitis (FIP) showed symptoms like not eating, weight loss, and being unusually tired. They were treated with an antiviral medication called GS-441524 for at least 12 weeks. The treatment was effective, and many of the cats improved significantly, with a notable recovery in their appetite and energy levels. This study highlig
- Clinical evaluation of a direct RT-qPCR method for feline coronavirus detection in effusions using the PicoGene PCR1100 system.
Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc · 2026 · Japan
A group of cats suspected of having feline infectious peritonitis (FIP) were tested for feline coronavirus (FCoV) using a new, faster method that doesn't require RNA extraction. This direct RT-qPCR method provided results in about 40 minutes and showed a high sensitivity of 95.5% and perfect specificity. This means it was very effective at detecting the virus without mixing up
- Evaluating the effectiveness of a two-set approach for improving blood culture positivity rates in dogs and cats.
The Veterinary record · 2026 · Japan
A study found that blood tests for sepsis in dogs showed a positivity rate of about 20%, whether one or two samples were taken. However, for cats, using two blood samples significantly improved the detection rate of infections, reaching nearly 90%. This suggests that if your cat is suspected of having sepsis, asking your vet about taking two blood samples could lead to a more a
Frequently asked questions
- Is FIP still a death sentence?
- No. GS-441524 has changed FIP from uniformly fatal to curable. Published studies report cure rates of 80-90%+ for effusive FIP. Neurological and ocular forms are harder to treat but still respond in many cases. Early diagnosis and prompt treatment give the best odds.
- Is FIP contagious to other cats?
- The parent feline coronavirus is very common and spreads easily in multi-cat settings, but the mutation to FIP happens inside an individual cat. You can't "catch FIP" directly — but cats in the same household share the underlying coronavirus exposure.
- How do I know it's FIP and not something else?
- Definitive diagnosis is tricky. A combination of clinical signs, a very low albumin:globulin ratio, positive Rivalta test on fluid, and immunostaining or PCR is the current gold standard. No single test rules FIP in or out on its own.