Feline Infectious Peritonitis (FIP) is a serious viral disease caused by a mutation of the feline coronavirus (FCoV).
It can affect cats of any age or breed, though it’s most common in young cats and multi-cat households. Not all cats exposed to FCoV develop FIP — only a small percentage experience this mutation.

FIP can appear weeks or months after infection.
Early signs include fever, loss of appetite, and lethargy.
There are four main types of FIP, each with distinct symptoms:

Wet FIP 
Fluid buildup in the chest or abdomen, causing a pot-bellied look and breathing difficulty.
Dry FIP
Inflammatory lesions in organs (liver, kidneys, brain, eyes), leading to neurological or vision issues.
Neuro FIP
Tremors, seizures, difficulty walking, or loss of balance.
Ocular FIP
Eye inflammation, cloudiness, or vision loss.
Some cats may show overlapping symptoms of more than one type.

Any cat exposed to FCoV can develop FIP, but young cats (under 2 years) are most at risk. High-density environments like shelters or catteries increase exposure risk. Genetics, stress, and weakened immunity can also contribute to FIP development.

There’s no single test that can confirm FIP. Diagnosis relies on a combination of clinical signs and tests, such as:
- Complete blood count (CBC)
- RT-PCR or PCR tests on effusion or tissue samples
- ALB/GLOB ratio (often < 0.7 in FIP cases)
Only your veterinarian can confirm the diagnosis based on these results and your cat’s overall condition.

No. The common feline coronavirus (FCoV) is contagious, but once it mutates into FIP, the mutated virus cannot spread between cats.
Healthy cats in the same household can safely stay together — just ensure good hygiene and a strong immune system.

Studies by Dr. Niels Pedersen and others have shown that GS-441524 is highly effective in treating FIP when given for 84 consecutive days.
- Available in injectable and tablet form
- Dosage depends on your cat’s weight and FIP type
- Completing the full course and 84-day observation period is essential for recovery
Cats that finish the full protocol and remain symptom-free afterward are considered cured.

Most medications can be used safely with GS-441524.
Avoid or limit:
- Steroids (can suppress immune response)
- Drugs with neurological side effects (can complicate monitoring) Flea treatments can be used if your cat has tolerated them before.

Quarantine is not necessary. The FIP mutation is not contagious between cats. In multi-cat homes, good hygiene and stress reduction are enough to protect other cats.