What Is FIP?
Feline Infectious Peritonitis (FIP) is caused by a mutation of feline coronavirus. Many cats carry intestinal coronavirus without any symptoms, but in some cats — especially young cats or those living in multi-cat environments — the virus can mutate and cause FIP.
Warning Signs That Need a Vet Visit
- A persistent fever that does not respond to routine treatment
- Lethargy, poor appetite and ongoing weight loss
- A progressively swelling belly (the "wet" form — fluid building up in the abdomen)
- Difficulty breathing, if fluid collects in the chest
- Eye or neurological changes such as uveitis or a wobbly gait (the "dry" form)
Why Diagnosing FIP Is Not Simple
No single test confirms FIP with certainty. Veterinarians assess several findings together: history and symptoms, blood tests (such as the albumin-to-globulin ratio), analysis of fluid drawn from the abdomen or chest, and ultrasound to evaluate fluid and internal organs. Some cases need additional laboratory confirmation.
Testing at Happy Pet Hospital
Our hospital has an in-house blood laboratory and ultrasound in one place, open 24 hours at both Sukhumvit and Ratchada. If your cat has a persistent fever or an unusually swollen belly, you can bring them in immediately — no waiting until morning. See our X-ray and ultrasound services for details.
Treatment Outlook Today
FIP was historically considered a disease with a poor prognosis, but treatment options have broadened in recent years. Early detection and close management under a veterinarian remain essential. If you suspect any of these signs, our veterinarians are available around the clock.