Feline infectious peritonitis in cats – signs and care

Updated 2026-09-30 · 2 sources

Based on: PDSA, International Cat Care (iCatCare)

Contact a vet today

Contact your vet today if you think your cat has this – it can become serious. It is a serious disease in cats caused by feline coronavirus.

What to do now

What you can do now

Contact your vet today.
Note when it started, how often it happens and what else you see.
Take a photo or short video to show the vet.
Keep fresh water available.
Let your cat rest somewhere calm.

Don't

Do not give any human medicine.
Do not wait if it gets worse.

What it is

Feline infectious peritonitis (FIP) is a disease of cats caused by feline coronavirus.^[1]^[2] FIP can be serious, and signs may happen suddenly or come and go over time.^[1] FIP is difficult to diagnose because other illnesses can cause similar signs and there is no single test that confirms it.^[1]^[2]

Signs

A fluctuating high temperature
Lethargy or tiredness
Reduced appetite or eating less
Weight loss
Vomiting or diarrhoea
Pale gums
Drinking and weeing more
A swollen abdomen or lump in the belly
Fast or difficult breathing
Loss of balance, tremors or fits

sudden

Causes and risk factors

British Shorthair cats
Maine Coon cats
Ragdoll cats
Bengal cats
Birman cats

How a vet finds out

Blood tests
X-rays
Ultrasound
Biopsy
MRI
Eye examination

How vets treat it

Hospitalisation
Medication
Steroids
Fluids or a drip
Diet change
Eye drops or ointment

Breeds prone to this

Veterinary charities list these breeds as more likely than others to get this condition. Each breed page lists the inherited conditions documented in the breed.

What the experts say

“Eating less or nothing ; Weight loss ; Low energy or lethargy ; Diarrhoea and sometimes vomiting ; Pale gums ; Drinking and weeing more ; Swollen abdomen (tummy) ; Fast breathing or difficulty breathing ; Lumps in the abdomen (tummy) ;”
— PDSA [1]

“Feline infectious peritonitis (FIP) is a disease of cats that occurs throughout the world caused by feline coronavirus. While it is a difficult disease to diagnose, there have been significant developments in the treatment of this once-fatal condition.”
— International Cat Care (iCatCare) [2]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

OkPaw is on Android now – an iPhone version is on its way.

Common questions

What is FIP?

FIP is a disease of cats caused by feline coronavirus. It is not the same virus as Covid-19 and cannot spread to humans.^[1]

How is FIP diagnosed?

FIP is difficult to diagnose because there are no signs specific to it and no simple blood test or single specific test to confirm it.^[2]

Can FIP be treated?

There have been significant developments in treatment, and studies show that antivirals can be effective in curing FIP in most cats.^[2]

Sources

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages