Feline infectious peritonitis (FIP) in cats

FIP is a fatal viral disease in cats that until very recently was considered incurable. Here you can read about symptoms of both dry and wet FIP, how the diagnosis is made and what you can do to prevent the infection.

What is feline infectious peritonitis (FIP)?

FIP (feline infectious peritonitis) is a fatal viral disease caused by the feline coronavirus. FIP is divided into two different disease forms; dry and wet.

Cats that first show symptoms of the dry form of FIP often eventually develop the wet form as well. A mixture of symptoms of both dry and wet FIP is common.

Symptoms of wet FIP

Fluid accumulation in the chest and abdominal cavity
Swollen abdomen due to fluid
Breathing problems due to fluid in the chest cavity
Reduced appetite
Fever
Weight loss

The wet form of FIP often affects younger cats and manifests as fluid accumulation in the chest and abdominal cavity.

The virus damages the blood vessels and causes fluid to leak out into the tissues. This causes the fluid accumulation. Cats with wet FIP are often round in the stomach. If the fluid is in the chest cavity, cats have difficulty breathing. It may be hard to see at first, but fast, shallow breathing is often observed.

Symptoms of dry FIP

Symptoms for a cat with dry FIP gets depend on which organs are affected. Changes are often seen in the eyes, brain, intestines, kidneys and liver. Sometimes unexplained fever peaks and emaciation are seen. The course is more stealthy. Cats lose their appetite, lose weight, becomes listless, and get a fever that comes and goes.

An infected cat can also have diarrhoea, eye inflammation and symptoms from the central nervous system.

The coronavirus causes FIP

FIP is a viral disease caused by feline coronavirus. The coronavirus is common among cats and is transmitted via faeces. The virus rarely causes symptoms, possibly mild diarrhoea. In some cats, there is a mutation of the virus that gives rise to FIP. The mutated virus is not contagious. With high infection pressure, the risk of a cat being affected by the mutated form increases.

Difficult diagnosis

Normally, a probable diagnosis is made as a result of symptoms, medical history, antibody measurement, blood tests, exclusion of other diagnoses, examination of body cavity fluid and tissue samples in combination with detection of virus. Autopsy is unfortunately the most reliable method for making a diagnosis.

The fact that the cat has antibodies does not necessarily mean that the cat is sick with FIP. The only thing the vet can determine is that the cat has at some point been infected with the Coronavirus, which caused it to develop antibodies against the virus. It could just as well be antibodies against the harmless variant of the virus.

Treatment of FIP

FIP is a disease in cats that until very recently was considered an incurable viral disease. Right now, studies are being conducted with new drugs with promising results so far, although the recurrence rate has not been established. The cost of the treatment varies and the drugs used are not yet registered for the purpose.

How to reduce the risk of FIP

By reducing the spread of coronavirus, the risk of the emergence of mutated FIP virus is also reduced. Since the virus is transmitted through the faeces, good hygiene is important. Have several litter boxes and clean them often, as well as food and water bowls. Avoid having many cats in a small area. The risk of FIP increases the more cats there are in the group per surface unit. If possible, let the cats go outside and make sure to avoid stress.

Written by Amanda Andersson, April 2024. Approved by licensed veterinary specialist Catarina Eliasson.