Feline infectious peritonitis (FIP) is a major viral disease of both wild and domestic cats that is almost always fatal. It was first discovered in the 1960s, and in 1970 the causative virus was identified as a coronavirus, which are a group of viruses that cause disease in pigs, dogs, and humans. However, FIP virus (FIPV) does not infect humans. Although coronavirus infection is common among cats, the incidence of feline infectious peritonitis is less than 1%. It occurs more commonly in multicat households and in purebred cats. For example, the Burmese breed seems to be more susceptible to FIP. Sometimes a period of stress occurs just before the development of FIP, such as neutering, vaccination, or moving.


FIP affects cats of all ages and both genders, but mostly young (kitten to two years) and older (fifteen years) cats. This may be due to the undeveloped immune system in the young cat, and weakening immunity in the older cat. It is possible for several kittens in a litter to develop FIP. It may be a factor in "kitten mortality complex," that is, the unexplained deaths of fetuses, newborns, and the very young.



Not all cats infected with the virus become seriously ill, but infected cats with mild symptoms or even no symptoms can become carriers and pass it on to other cats for as long as several years. A carrier cat that develops lowered immunity may eventually develop the full-blown disease.


Although the way FIPV is spread is not yet clear, the major source of the virus is in the feces of cats. Since it is rather unstable, it cannot survive more than a few weeks in the environment, so environmental spread is probably not a major source of the infection. It is also possible for cats that have had no contact with diseased cats to develop FIP. In multicat households that have had cats with FIP, it may mysteriously recur after months of being free of disease.


After a cat ingests the virus, replication follows in the pharynx and small intestine. The virus can be shed from the throat, lungs, stomach, and intestines and spread to other cats one to ten days later. It then reaches the lymphoid tissue, and eventually the infection spreads throughout the body. The virus may incubate for as long as several years before symptoms appear, when the disease is no longer contagious.


There are a number of strains of FIPV--some more virulent than others--and a cat with a strong immune system may not develop the disease. The presence of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) may predispose a cat to the development of FIP.

Some of the initial clinical signs of FIP are fever, vomiting, diarrhea, loss of appetite, weight loss, and lethargy. Other cats have sneezing, watery eyes, and nose discharge. Several weeks later, more definitive symptoms appear. The disease at this point is divided into wet or dry, but many cats have a mixture of the two.


In wet FIP (around 60-70% of FIP cases), fluid accumulates in body cavities--most commonly the abdominal cavity--with gross abdominal swelling; or the thoracic cavity, which may cause breathing problems.


In dry FIP, lesions develop in different sites, and symptoms depend on what organs are affected. In up to 50% of cases, eye inflammation or neurological problems such as paralysis, unsteady gait, and seizures will develop. Other lesions may affect the kidneys, liver or gastrointestinal area.


FIP is difficult to diagnose through standard laboratory tests, and many veterinarians don't bother with blood tests. However, some tests can help point to FIP as a cause for your cat's condition. The coronavirus titer test can determine the presence of coronavirus in your cat. X-ray and analysis of fluid present in the body cavities is one of the most useful tests. Examination of biopsied tissue is another way FIP can be confirmed.


Thus far, there is no effective treatment available for FIP. Infected cats can be treated symptomatically, but euthanasia becomes the only option as the disease progresses. Alternative veterinarians recommend homeopathy, herbs, and nutrition to treat symptoms, but not as a cure.


The most effective way to deal with FIPV is through strict control of infection. In a multicat household, any cats with signs of possible FIP should be isolated and kept indoors until a diagnosis is made. This is especially important if the cat is pregnant. After her kittens are born, they should be removed from her after four to six weeks (by that time they will have acquired antibodies from the mother, and started producing their own) to protect them from acquiring any viruses from her, including FIPV.


Hygiene is crucial in controlling FIPV. Make sure litter boxes are scooped daily, throw away the rest of the litter every week, and disinfect the boxes with bleach. Also clean and disinfect the area around the box. Use at least one litter box for every two cats. Change food and water daily, and disinfect bowls and utensils weekly. Almost any common household disinfectant can be used to destroy FIPV, which can survive up to three weeks in the home.


Other measures to control FIP include minimizing stress, especially if you have more than one cat. Do not bring new cats into the home for six months. And you might consider screening your cats for feline leukemia virus and feline immunodeficiency virus, which suppress the immune system of the cat and predispose it to developing FIP.


A vaccine is available for FIPV, but it is controversial and some veterinarians do not recommend it. Studies are continuing to create a more effective vaccine that will cover all strains of FIPV.

My vet tested Miley for FIP and she tested positive. That means that she was exposed to it, not that she has it. She does have issues with soft stools and we are working on that. So although she tested positive it seems that testing the other three cats is pointless because there is no treatment for it! Something else to worry about!

Now aren't you sorry you asked?