Feline infectious peritonitis

Affects: Cats

Overview

Feline infectious peritonitis (FIP) is a common and aberrant immune response in cats to infection with feline coronavirus (FCoV).

Signs & Symptoms

Clinical Signs: There are two main forms of FIP: effusive (wet) and non-effusive (dry). While both types are fatal, the effusive form is more common (60–70% of all cases) and progresses more rapidly than the non-effusive form.

However, symptoms have been noted to occur before these stages including:

Lethargy

Decreased or no appetite (anorexia)

Weight loss

Diagnosis

Diagnosing Effusive Fip: Diagnosis of the effusive form of the disease has become more straightforward in recent years. Detection of viral RNA in a sample of the effusion (liquid drained from body), such as by reverse transcription polymerase chain reaction (RT-PCR) is diagnostic of effusive FIP. Nonetheless, that does require that a sample be sent to an external veterinary laboratory. Within the veterinary hospital there are a number of tests that can rule out a diagnosis of effusive FIP within minutes:

Measure the total protein in the effusion: if it is less than [dose — ask your vet]/L, FIP is extremely unlikely.

Measure the albumin to globulin ratio in the effusion: if it is over 0.8, FIP is ruled out; if it is less than 0.4, FIP is a possible—but not certain—diagnosis.

Treatment Approach

Treatment: Because FIP is an immune-mediated disease, treatment falls into two categories: direct action against the virus itself and modulation of the immune response.

Prevention

Prevention: Stopping the spread of FIP can be difficult, especially with only one known FDA approved treatment available in the United States. Because of this, it is important to be proactive and try to prevent FIP before the disease can begin its destructive turmoil. Preventing FIP also differs depending on the facility or environment of the cat.

In shelters and areas with high numbers of cats in confinement, prevention is essential as it only takes one cat to start a chain-reaction and spread of FIP. Prevention includes: antibody testing, environmental enrichment to decrease stress, multiple litter boxes that are cleaned regularly to prevent the spread in fecal matter.

Disinfection is also a key factor in stopping the spread of FIP. FCoV particles can be disinfected with products such as diluted bleach, UV light, and heat.

Educational information only. This page is general guidance and is not a substitute for professional veterinary advice. Never give medicines or change treatment without consulting a veterinarian. If your pet is unwell, contact OC Pets or seek emergency care.
Sources (reused under open licences, with thanks): Wikipedia — “Feline infectious peritonitis” (CC BY-SA 4.0) · Compiled by OC Pets Veterinary Clinic, updated 15-06-2026.