Feline Infectious Peritonitis: What Every Cat Owner needs to Know

Feline Infectious Peritonitis

Is Your Cat At Risk of Feline Infectious Peritonitis (FIP)?

FIP is a viral disease of cats, which causes fluid to build up in the belly (there is also a ‘dry’ form). The condition has a poor long term outlook, with the average survival time post diagnosis being just nine days. It is a particular heart-breaking illness because there is no effective treatment.

Even more worryingly the virus causing this disease, feline coronavirus, is common. Figures show around 30% of pets cats have come into contact with coronavirus at some point, with the figure startlingly higher amongst shelter cats. Happily, the numbers of cats which fall ill with FIP is much lower, at around 1%, which poses the question: Why don’t more cats become seriously ill?

Knowing the answer to this question could make the difference between having a healthy and a sick cat.  So let’s look more closely at the whys and wherefores of FIP, so you are better placed to protect your cat.


Which Cats are Most at Risk?

The following groups of cats are most likely to develop the life-threatening disease FIP

  • Those under 12 months of age
  • Those in multi-cat households
  • Shelter cats or kittens from breeders
  • Cats with weak immune systems as a result of other illnesses.

Turning things on their head, the cat least likely to develop FIP is a lone pet cat with some access to outside and is less likely to use a litter box.

This may sound a bit random, but once you know more about coronavirus and FIP, it begins to make perfect sense.


The Quirks of Coronavirus

Coronavirus is very common, which sounds scary until you realize that it’s quite a quirky virus. Some of its characteristics include:

  • It’s common, especially amongst cats living together in groups
  • The virus can survive for 7 weeks in a dry environment
  • Coronavirus is killed by most disinfectants
  • Coronavirus can cause a mild diarrhea in cats that clears up of its own accord
  • Coronavirus mutates from a relatively harmless form to the strain causing serious disease

OK, did you spot the key fact there? Coronavirus MUTATES. It changes from a relatively innocuous virus causing mild, short term diarrhea, to become a potential killer.

How and why does this change take place?

Cats are a bad influence on coronavirus. By that we mean that each time the harmless form is excreted in diarrhea and picked up by another cat, the virus gets a bit meaner. When that second cat has diarrhea and cat three picks it up, the coronavirus gets meaner still. This has a technical term “passage” of the virus, and the more time the virus passages through a cat the more virulent it becomes, until eventually it causes FIP.

This is why the potential for FIP infection is greatest in multi-cat households, breeding establishments or shelters; because sharing litter trays and repeated contact with feces is the perfect breeding ground to mutation.


What are the Symptoms of FIP?

We’ve already mentioned coronavirus causes mild diarrhea. This is what happens to the majority of that 30% of cats that have come into contact with coronavirus. They catch the virus, their immune system fights it, they get well again…but shed coronavirus for weeks afterwards…ready for other cats to catch…

Those cats that catch the virulent virus causing FIP are likely to show mild signs at first, such as:

  • A waxing and waning fever
  • Poor appetite
  • Weight loss

As the disease gets hold, the commonest ‘wet’ form of FIP causes fluid to build up in the body cavities. Symptoms include:

  • Fluid on the belly
  • Fluid on the outside of the lungs
  • Inflammation of the inner chambers of the eye

(There is a ‘dry form of FIP which is equally serious, but even more difficult to diagnose.)


Diagnosing FIP

Given the serious natures of FIP it’s important the vet gets the diagnosis right. The only problem is there is no one reliable, definitive test for FIP. What the clinician has to do is rule out other conditions and build the evidence that FIP is the most likely diagnosis.

This detective work involves:

  • Screening blood tests to look for shifts suggestive of FIP
  • A blood test to prove the cat has been in contact with the coronavirus
  • Analyzing the makeup of the fluid on the belly
  • Biopsy of affected organs

Importantly, a positive blood test for coronavirus does NOT automatically mean the cat has FIP. It means the cat has been infected with coronavirus, but the test can’t tell the difference between the relatively harmless and the super virulent strain. The only conclusion the vet can draw is if the test is negative, which means the condition cannot be FIP as the cat hasn’t been in contact with coronavirus.


Treatment of FIP

It’s tough news because there is not proven, effective treatment for FIP.

Corticosteroids can help improve the cat’s quality of life in the short term, but they aren’t a cure. Interferon may help some cats to go into remission, but its usefulness is open to debate.

All of which means prevention is better than cure.


Preventing FIP

If you’ve just brought a kitten into a house with established cats, you may be feeling rather worried right now. But don’t worry because you can reduce the risks. Key to this is good litter tray hygiene.

The coronavirus needs to ‘passage’ through cats via contact with feces in order to mutate. By keeping litter trays scrupulously clean, and pooper scooping a minimum of once or twice a day, you reduce the opportunity for cats coming into contact with feces and therefore coronavirus.

Also, providing a tray for each cat, means they’re less likely to cross contaminate each other. If this isn’t possible or practical, then at the very least using an automatic litter tray goes someway to help by keeping things hygienic.

In addition, disinfect the trays regularly, since this will kill any lurking coronavirus.

And finally, although FIP is a serious condition, by observing rigorous tray hygiene and being sensible about how many cats you keep, you can reduce the risk of FIP and the chances of your pets becoming sick.