Feline Infectious Peritonitis

Unfortunately there is still a lot we don’t know about this disease. It is a virus in the coronavirus family, a large group of viruses some of which are quite normal and harmless inhabitants of many cats’ digestive systems. The FIP virus may be a particular strain of virus or it may be one of these normal coronaviruses that somehow changes within the cat’s body to cause illness. We know that FIP is contagious from cat to cat, but there seems to be some necessary interaction with the cat’s immune system to actually cause disease, and some cats seem to be naturally resistant.

FIP virus is shed in the feces of infected cats. The most common way it is spread is through fecal-oral transmission - one cat sniffs or steps in stool from another cat that harbors the virus. However, there have also been reports of strains of FIP that seemed to spread by aerosol transmission - airborne particles from sneezing or coughing. It is often seen later in other cats in a household once a positive case has been diagnosed. The FIP virus has been found to survive in damp areas for at least 4 months, so it may be transmitted even after an infected cat leaves the household.

Signs of FIP often develop very slowly over a period of months. The symptoms are not so much a result of the viral infection itself, but in great part arise from the response of the cat’s immune system to the virus. Affected cats develop vasculitis - inflammation of the blood vessels. Inflammatory immune system cells congregate along blood vessels wherever the virus is found. The blood vessels then become leaky, and fluid may ooze out into the chest cavity, causing respiratory signs, or into the abdominal cavity, causing a fluid-filled, distended abdomen. (Peritonitis means inflammation in the peritoneum or abdominal cavity.) Some cats don’t leak much fluid but instead have more dry, plaque-like areas of inflammation in the chest and/or abdomen. Liver and intestinal inflammation can occur as well. Vasculitis can also be seen in the eyes, occasionally causing blindness, or the brain, leading to neurological problems.

Early signs are very vague and mimic other diseases. Loss of appetite, high fever, a distended abdomen, intermittent or chronic diarrhea or labored breathing may be signs. As the disease progresses, more symptoms develop, including difficult breathing, weight loss and emaciation. Death may eventually occur from suffocation caused by a buildup of fluid in the chest, restricting the ability of the lungs to inflate with air. Severe debilitation, liver failure or dehydration may also lead to death.

Diagnosis is difficult in the early stages because there is no good blood test for FIP. The blood test we do have is cross-reactive with similar coronaviruses that do not cause the FIP disease. A positive blood test may mean a cat has FIP - or it may not. Some cats seem to become carriers, shedding the virus without becoming ill. These carrier cats then expose other cats to the disease.

There is NO known cure for FIP. Although some cats may be carriers with no apparent symptoms, it is always fatal once the cat becomes ill. Sometimes treatment can provide temporary relief. Antibiotics help control secondary infections such as pneumonia, and steroids such as prednisolone help reduce the degree of vasculitis. Treatment does not reverse the course of the disease, however.

There is a vaccine available to prevent FIP. It is not 100% effective, probably closer to 85%, but it is safe and simple to administer. The vaccine is given intranasally - as nose drops. It is not painful. Research shows the vaccine to be effective when given to healthy cats before exposure to the disease has occurred.

Cats who spend time outdoors are at risk for acquiring the FIP disease and should be vaccinated against it. If you plan on acquiring a new cat you may want to vaccinate your current cat(s) against FIP in case the newcomer is a carrier.

The more cats you have in a household the higher their risk for FIP. It is common in outdoor cats and in breeding colonies. Feline Infectious Peritonitis can devastate a cattery - testing for carriers is not reliable and selling cats or kittens that later become ill with FIP doesn’t give you a good reputation in the cat breeding world! Until a better test is developed, vaccination is the best option for breeders.

Infected cats should be isolated to prevent the spread of the disease. If other cats are present in the household, practice good hygiene and sanitation by frequent cleaning of food and water bowls and litter pans. If you have a "positive" cat, do NOT bring a new cat into the household as long as that cat is present. Thirty days after that cat is no longer in the household, other cats in the household should be tested for the disease. If they are all negative, you’re safe. If any test positive it may mean the disease is present or it may be a crossover reaction from another similar virus. If there are no other cats in the household, wait a few months before bringing in a new cat - remember, the virus can survive for several months. Disinfecting with 4 ounces of Clorox in one gallon of water is effective in killing the virus.