FIP in Cats (Feline Infectious Peritonitis): What It Is, Signs and Risk

See a vet promptly if your cat has trouble breathing, a swollen belly, wobbliness or a seizure, or a fever and low appetite that won't settle. These signs need a proper check by a licensed vet [1][3][4].

Feline infectious peritonitis (FIP) is a serious disease of cats. It develops when a very common, usually harmless cat coronavirus changes inside one cat's body [1][2]. Hearing the name can be frightening, so here are the calm, clear facts.

What is FIP in cats?

• FIP is a severe illness driven by the cat's own immune response to a changed (mutated) form of feline coronavirus (FCoV) [1][2][5].
• Most cats that catch FCoV only get a mild tummy upset, or no signs at all [1][3].
• Only a small proportion of infected cats go on to develop FIP. North American and European sources commonly put this at around 5–10% [1][2].
• Vets describe FIP as one of the most important infectious causes of death in young cats [5][6].

Is FIP the same as cat coronavirus?

Not quite. Feline coronavirus is the common virus that spreads between cats. FIP is the disease that can follow when that virus mutates inside an individual cat and the cat's immune system reacts strongly to it [1][2][3].

Is FIP contagious to my other cats?

FIP itself is not considered contagious between cats. The change that turns the harmless virus into FIP happens inside one cat, and it is not known to pass to other cats in that form [1][2][3].

What does spread is the everyday coronavirus (FCoV). It passes mainly through faeces, often indirectly through shared litter trays [2]. Shared bowls, mutual grooming and close contact can also play a part [4]. Kittens most often pick it up early in life, commonly from their mother [1].

Can people or dogs catch FIP?

No. Feline coronaviruses only infect cats and cannot be passed to people [3]. FIP is not related to COVID-19 in humans, even though the viruses belong to the same broad family [3].

What is the difference between wet and dry FIP?

• Wet (effusive) FIP: fluid builds up in the belly or chest [1][2][4].
• Dry (non-effusive) FIP: inflammation affects organs such as the liver, kidneys, eyes or brain, without obvious fluid [1][2][4].

In practice, many cats show a mix of both, and either form can affect the eyes and nervous system [1][2][4].

Which cats are most at risk?

• Young cats. FIP mostly affects young cats, often under two years old [1][3].
• Some pedigree cats. Several pedigree lines are reported to be affected more often, but the breeds named differ between sources [3][4]. No single breed is "the" at-risk breed.
• Male cats are reported to be affected slightly more often [1][2].
• Cats in groups. Shelters, breeding catteries and crowded multi-cat homes carry more risk, because the coronavirus spreads more easily there [1][2][3].
• Recent stress. Events such as rehoming, a shelter stay, neutering or another illness often come before FIP appears [2][3].

A positive coronavirus (FCoV) antibody test on its own does not mean a cat has FIP or will get it. It only shows the cat has met the common virus [1][3][4].

What are the signs of FIP?

• Ongoing fever, tiredness, poor appetite and weight loss that don't go away, especially in a young cat [1][3][4][5].
• A swollen, "pot-bellied" tummy, or trouble breathing [1][3][4].
• Eye changes: cloudiness, a change in colour, or bleeding inside the eye [3].
• Wobbliness, poor coordination or seizures [1][3][4].
• Yellowing of the gums, skin or eyes, or vomiting or diarrhoea that doesn't settle [3].

When should I see a vet?

See a licensed vet promptly if a young cat shows unexplained illness that is getting worse. This matters even more after a recent move, a shelter or cattery stay, or surgery [2][5][6].

FIP is hard to diagnose, even for vets, and needs a proper veterinary work-up rather than guesswork at home [5][6].

Is there a treatment for FIP?

For a long time, FIP was considered almost always fatal once signs appeared [1][4]. Treatment options have changed in recent years. Please discuss what is legally available with your own vet.

How can I lower the risk?

There is no way to guarantee a cat will never get FIP, because the coronavirus behind it is so widespread [1][2][3]. You can lower the risk:

• Keep litter trays clean and place them away from food and water [2][3].
• Provide enough trays. A common guide is one tray per cat, plus one extra [2][3].
• Keep groups small and stable and avoid crowding [1][3].
• Reduce stress around big changes such as rehoming or surgery where you can [2][3].

What about a vaccine? An FIP vaccine exists in a few countries, but the American Association of Feline Practitioners does not generally recommend it, and its effectiveness is described as questionable [1][4]. It can also only be given after 16 weeks of age, when many kittens have already met the virus [3].

FAQ

Is FIP always fatal?

It was long seen as almost always fatal [1][4]. Treatment options have changed in recent years, so talk to your vet about what is legally available.

My kitten tested positive for coronavirus. Does it have FIP?

Not necessarily. A positive test only shows exposure to the common virus, which is usually harmless [1][3][4]. Ask your vet about what to watch for.

Can FIP be treated in Saudi Arabia?

This depends on current regulations, which can change. Ask your vet what's legally available in Saudi Arabia right now [2][3][4].

How do I protect my other cats?

FIP itself is not considered contagious [1][2][3]. Good litter hygiene, enough trays and small, calm groups help limit the everyday coronavirus [1][2][3].

Which breeds get FIP?

Several pedigree lines are reported to be more affected, but lists vary between sources [3][4]. Any cat can be affected.