Feline Infectious Peritonitis (also called FIP) is a serious disease caused by a coronavirus that affects domestic cats, especially young ones (often under two years old). It typically comes on suddenly and can progress quickly if left untreated.
FIP appears in two main forms:
- The “wet” form (also called “effusive”) causes fluid to build up in areas of the body where it shouldn’t be—like the abdomen, chest, or around the heart. This can lead to a swollen abdomen and difficulty breathing.
- The “dry” form causes inflammatory lumps or nodules to form in organs, which can damage the body in many different ways. It can affect the eyes (causing discharge, cloudiness, or even blindness) or the nervous system (leading to seizures, wobbly walking, or difficulty moving) or other organ systems.
Unfortunately, there’s no single test that definitively confirms FIP, therefore, veterinarians usually make the diagnosis based on the cat’s symptoms and several different test results. Scientists are currently studying viral pathogenesis, mutation, transmission, and prevention.
A Treatment Option for Feline Infectious Peritonitis
For decades, there were no effective treatments and a diagnosis of FIP was almost always fatal. Thankfully, that has changed! A new antiviral drug called GS-441524, approved for use in the U.S. in 2024, can now be used to treat FIP. This medication works by stopping the virus from multiplying in the body. The course of treatment is typically 12 weeks long and requires a strong commitment.
With early diagnosis and proper treatment, many cats can survive. Success rates with antiviral therapy and supportive care range from 77% to 96%, depending on the form of FIP and how soon treatment is started.
