Feline Infectious Peritonitis (FIP)

Hearing that your cat has Feline Infectious Peritonitis (FIP) is one of the worst bits of news you can get from your vet. The disease is almost always fatal, although treatments can make your cat’s remaining time more comfortable. If you have more than one cat in your home, taking sensible precautions and following your vet’s advice can help to reduce the risk that your other cats will be affected.

The disease is caused by a virus which is often found in healthy cats and usually causes no major health problems. However, in some cats it causes serious disease.

The disease has two different forms. The more common form is called ‘wet FIP’ because the blood vessels leak, fluid oozes out of the blood and the cat’s belly swells. This may also occur in the chest stopping the cat from breathing properly. The less common form of the disease is ‘dry FIP’ in which there is no build up of fluid but thick scar tissue develops on the cat’s internal organs. Except in rare cases, wet FIP is fatal within about five weeks of diagnosis. The dry form is equally deadly but affected cats may survive for a few months. The accompanying picture shows a cat with wet FIP.

The most vulnerable cats are those with weak defences against infectious diseases – kittens, elderly cats and those already suffering from some other condition. Some pedigree breeds such as Burmese appear to be affected more often than ordinary domestic ‘moggies’. Only about one in a hundred cats is likely to go down with the disease but the risk is much higher where several cats live together such as in a breeding cattery or rescue centre. Overcrowding and other stressful factors can increase the risk of disease developing.

In its early stages, FIP causes a variety of symptoms which can easily be mistaken for other diseases:

  • weight loss
  • lethargy
  • a dull coat
  • diarrhoea
  • poor appetite
  • fever.

Later on your cat’s eyes or nervous system may be damaged causing blindness and paralysis. In the so called ‘wet form’ of the disease fluid may build up in your cat’s tummy (causing swelling of the abdomen) or chest (causing difficulty in breathing).

There is no completely reliable blood test to show that your cat has FIP. Blood tests will just tell your vet that your cat has been infected with a virus which could be FIP. Other samples can be taken from fluid in the chest or abdomen. The only sure method of diagnosis is to take a tissue sample from one of the internal organs. This is often done after the cat has died to confirm that the cause of death really was FIP.

There is no evidence that the FIP virus can cause any disease in humans or other animals such as dogs.

Medicines such as steroids, vitamins and minerals are often given to make your cat feel better, but they do not tackle the disease itself. With careful treatment you may be able to keep your cat healthier for a little longer. Interferon (a powerful drug that suppresses immune reactions) may be helpful in some cats but is very expensive and generally does not provide much increase in life beyond the use of steroids).

In the future it may be possible to treat FIP with one of the anti-viral drugs that are being developed for use against human diseases but this is likely to be many years away.

The virus is spread in the cat’s saliva, phlegm and in its faeces (droppings). Some cats contract the virus but ae able to fight off the disease. These cats may continue to carry the virus and infect other cats. A cat with suspected FIP should be kept indoors in a separate room so as to avoid direct contact with all other cats. It should have its own feeding bowl and litter tray and these must be cleaned every few days.

The virus does not survive long outside the animal and it can be killed using a dilute solution of household bleach (about five tablespoons of bleach in a gallon of water). Use this to clean the feeding bowls, etc. and to wipe down room surfaces.

An FIP vaccine has been developed in the US but vets disagree on how effective it is in preventing symptoms of FIP and it is not yet available in the UK. Vaccinating healthy cats against other important virus diseases, such as Feline Leukaemia, keep their defences strong and may reduce the risk of them getting FIP.