Feline infectious peritonitis

Feline infectious peritonitis (FIP) is a fatal viral disease in cats caused by an infection with feline coronavirus (FCoV). FIP is caused by feline coronavirus, but this is not the same virus as Covid-19 and it does not affect humans.

Feline coronavirus is very contagious. Infections are very common in cats around the world, including the UK. But it is more common in large groups of cats, such as multi cat householders and breeding catteries. It's also common in young cats, often under two years old, but it can be seen in older cats too.

Signs of feline coronavirus

In most cats, feline coronavirus causes no symptoms or only mild transient diarrhoea that gets better without treatment within a few days. Sometimes feline coronavirus causes the more serious condition of feline infectious peritonitis or FIP.

When does feline coronavirus become FIP?

Occasionally feline coronavirus will mutate inside of a cat. If their immune system reacts in a certain way it can lead to FIP. But most cats with feline coronavirus will not develop this condition, although they can still pass on feline coronavirus to other cats.

Types of FIP

FIP is generally considered as two types:

1. Effusive (or wet) FIP
2. Non-effusive (or dry) FIP

It is now thought that cats often have a mixture of the two types, or both types at different stages of the condition. Unfortunately the symptoms of FIP are likely to be very similar to lots of other illnesses so it can be difficult to diagnose.

Effusive (wet) FIP

Effusive disease is more common than non-effusive and in general accounts for around 60 to 70 per cent of cases.

If your cat has effusive FIP, fluid can build up in their abdominal cavity and chest, causing swelling and breathing difficulties.

Symptoms of effusive FIP in cats

• A lack of appetite
• A distended, swollen or bloated stomach which shows within days or weeks
• Fast or laboured breathing
• Fever
• Diarrhoea
• More tired or lethargic
• Avoiding food
• Jaundice

Non-effusive (dry) disease

If your cat has non-effusive FIP, symptoms can be less specific and more difficult to spot. The condition can affect lots of different vital organs in the body leading to a wide range of symptoms.

Symptoms of non-effusive FIP in cats

• A lack of appetite
• Fever
• Weight loss
• Lethargy or tiredness
• Diarrhoea
• Jaundice
• Red eyes
• Neurological signs (eg being wobbly on their feet or having fits)

I'm worried my cat has FIP

If you are concerned about FIP or any of the signs mentioned above, you should book an appointment to see your vet.

Testing and diagnosis for FIP

FIP can be difficult to diagnose. Symptoms will often be similar to other conditions and there is no simple blood test. If your vet suspects FIP because your cat has feline coronavirus and symptoms of FIP, they may also want to take ultrasound scans, bloods and fluid tests to confirm a diagnosis.

Treatment of FIP

Treatment for FIP can vary in length. Some cats will need treatment for several days while others will need treatment for several months. Sadly, in many cases, by the time symptoms of FIP are present, the disease is very advanced and treatment may not be possible.

Vets will try to stabilise your pet, which could involve intravenous fluids via a drip, nutritional support and medication. Some anti-viral drugs have been developed and are licenced in the UK, but these can be expensive and your cat may need this medication for many months. In critically ill cats or very advanced cases of FIP, your vet might recommend putting your cat to sleep to avoid their suffering.

Is there a vaccine for FIP?

A commercial FIP vaccine has been developed, however this vaccine cannot be used in kittens under 16 weeks of age, and many will already be exposed to feline coronavirus before this age. It is not currently available in the UK.

Large groups of cats, such as those in breeding catteries, rescue centres or households with lots of cats are most at risk. But there are some sensible precautions you can take to help protect your cat from infectious diseases like feline coronavirus and reduce the risk of FIP:

• Avoid keeping cats in large groups (ideally no more than four cats, although most cats are happiest when they're the only cat)
• Avoid getting a cat from a home or breeder who keeps large groups of cats or multiple litters of kittens at once
• Have at least one litter box for every two cats
• Keep litterboxes far away from food and water bowls
• Clean your cat's food, water bowl, litter tray and the surrounding area daily
• Keep stress in your cat to a minimum
• Keep up with their health checks and healthcare needs