Feline Infectious Peritonitis (FIP)
Roger Ross, DVM
FIP is caused by one of the many types of Coronavirus and frequently affects the central nervous system. The disease itself is fairly uncommon, (about 10 cats a year at our little clinic) but almost always fatal once the cat starts acting sick. We see it mainly in young cats under 3 years old.
The progress of the disease in the cat patient, as with many other diseases, depends on the dose of virus and the immune resistance of the cat. This is yet another reason to maximize the health of your pets through regular vaccination, parasite control, and a high quality diet.
Signs include paresis (near paralysis), high fever, weight loss, depression, lack of coordination, nervous signs and eye disease.
Often, the belly is distended with fluid due to peritonitis or inflammation of the abdominal cavity. Most of the FIP patients I see look and act extremely sick.
The disease is contagious, mainly from respiratory spittle, but also from other body fluids, and germs left on food bowls etc.
Your vet will be suspcious that your cat has FIP if your young adult cat is very sick and especially if there is fluid in the chest or abdomen, but a lot of FIP cats, while very ill in general, don't have any symptoms that are specific for this one disease.
In other words, there are lots of diseases that cause fever, eye discharge, poor appetite, lethargy, and minor neural signs like weakness, stupor, and incoordination.
For that matter, there are lots of diseases that cause fever and when cats are feverish, they get eye discharge, have poor appetites, are lethargic, and are often in a stupor.
It's difficult for your vet to make a conclusive diagnois for FIP:
If your sick cat has a bloated abdomen, we often insert a syringe needle into the belly and extract the fluid if present. If there is fluid and it's yellow and tacky typical of peritonitis that's a big clue your cat has FIP ... but there are other, less fatal causes of peritonitis, and more important, not all FIP patients have peritonitis bad enough to produce noticable amounts of fluid (we call this the "dry form of FIP) and besides, by the time the fluid in the abdomen becomes noticable, the disease is so far advanced your kitty is near death.
There aren't simple, highly accurate, in clinic test kits for FIP available like we have for leukemia and Feline AIDS.
We can send multiple blood samples to commercial labs to get a titer which tells us if your cat's immune system has responded to Corona virus but such tests are not specific for FIP; a high titer could mean your cat has FIP, but it could also mean your cat's immune system responded in the past to other more common corona diseases such as feline panleucopenia or feline enteritis. Or (I think this is correct), a high titer could be a result of your cat's vaccine history. At any rate; it's difficult to be sure and we hate to recommend euthanasia when it's possible your cat is simply suffering from a severe case of flu, respiratory complex, or enteritis.
There is a fairly new vaccine available now, but there seems to be some controversy on it's effectiveness and on whether or not it should be recommended as a routine vaccine for most pet cats.
One more big comment:
FIP cats OFTEN GET FIP because their immune systems are suppressed from other diseases ... especially leukemia ... or poor nutrition or parasitism. So maybe the best prevention is making sure your kittens and young cats are vaccinated for leukemia, offered a good diet and parasite control.
Unfortunately, there are lots of feral, stray, semi stray, and just plain unvaccinated pet cats wandering around most communities and if a nice person rescues such a cat there's a chance it may be harboring FIP corona virus that in months to come ... after you've become attached and have had your new rescue cat seen by a vet and vaccinated and neutered ... will cause deathly illness.
