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Ask Suzanne Hurst, DVM:
FELINE INFECTIOUS PERITONITIS (FIP) I usually get one of two responses from cat lovers when the topic of FIP comes up—either a look of confusion because they are not familiar with the disease or a look of fear because they are. Personally I despise and dread this disease not only because it can be extremely difficult to diagnose, is very hard to prevent, impossible to cure and invariably fatal but also because I lost my own very special little rescued kitten, Rudy, to this disease a little over a year ago at 6 months of age. I have positively diagnosed half a dozen or so FIP cases during 15 years in practice but I would not doubt that there were cases that went undiagnosed or were misdiagnosed due to the extreme difficulty in accurately diagnosing this horrible disease. This may be especially true for the geriatric cat population. When an older cat presents for kidney or liver failure or neurologic issues it is natural to assume that their condition is attributable to the aging process, but it is also possible that a resurfacing of a latent coronavirus infection is to blame. What is this poorly understood and extensively researched disease? FIP is a systemic and fatal disease caused by a type of coronavirus that infects cats. But it is more complicated than that. Infection with the feline enteric coronavirus (FECV) is very common but the development of FIP is very uncommon. How does a cat contract the virus (FECV) that can mutate to the disease, FIP? FECV is highly contagious; it is estimated that between 30-40% of all household cats are infected. The infection occurs primarily through a fecal-oral route. Infected cats shed the virus in their feces and cats that share the litterbox invariably pick up some of these virus particles and ingest them while grooming themselves. How does this coronavirus (FECV) become FIP? Once infection with FECV occurs, the virus infects cells in the lining of the cat’s intestines. Because of the physical structure of the virus it is prone to mutations during replication. One of the mutations that can occur to the coronavirus is termed feline infectious peritonitis (FIP). This name is not quite accurate because after the virus mutates into the FIP form it is does not appear to be “infectious” anymore. Cats do not “catch” FIP. They catch the coronavirus and then, if it mutates into the FIP virus form, their immune system reacts and causes the illness FIP. Fortunately this only happens in about 5% of infected cats. The development of FIP often follows a stressful event such as surgery or being re-homed and is primarily a disease of kittens and very young cats; the peak age for diagnosis is 10 months. What are the symptoms of FIP? Symptoms are dependent on whether the cat suffers from the wet form or the dry form. All cats with FIP will have varying degrees of lethargy, inappetance, and a fluctuating fever that is unresponsive to antibiotics. The wet form is more severe and causes death more rapidly, often within a few weeks of the appearance of symptoms. Fluid accumulation can cause a distended abdomen and in the chest cavity causes breathing difficulty. Tentative diagnosis can often be made by collecting and examining the fluid. By contrast, the dry form can result in vague symptoms, but may include neurological difficulties, eye lesions or symptoms related to liver or kidney inflammation. Cats suffering from the dry form have survived for several years but most die within a few months. Can a test be done to determine if a cat has FIP? There is no reliable test for FIP except biopsy of an affected organ. Many diagnoses are made after death via a necropsy (veterinary term for autopsy). Tentative diagnosis is based on symptoms and certain abnormalities on standard blood tests. Doing a corona titer for antibodies in the blood merely indicates exposure to the enteric coronavirus and does not correlate with an active or imminent FIP infection. There is a newer test that detects active coronavirus in the feces but, again, this does not mean a cat has FIP, only that they are shedding FECV. What is the treatment? Treatment is difficult because it is the immune system’s response to the virus that causes lesions and symptoms, not the virus itself. Steroids and the use of feline interferon has limited success in treating some cats, but the disease will ultimately progress. For now we are only able to provide supportive care though some studies are being done with immune system modulation drugs. Is there a vaccine to prevent FIP? The American Association of Feline Practioners (AAFP) does not recommend routinely vaccinating against FIP. While a vaccine came out in 1991, some researchers feared it might actually make the disease worse if a cat had already been exposed to the FECV, but agreed that it would not protect cats if they have been exposed to the coronavirus. Even most kittens have been exposed by the time they can receive the vaccine at 16 weeks. How can I best protect my cats? Scrupulous and frequent cleaning of the litter pans and prompt clean-up of spilled or tracked litter is important. The virus is easily killed by common household cleaners such as dilute bleach (1 part bleach to 32 parts water). Clumping litter is best and it needs to be scooped often. Clean the scooper and the litter boxes with dilute bleach weekly. Of course if you allow your cats to go outdoors there is always a risk of exposure. Cats with FIP are not a risk to other cats and do not need to be isolated. Any cats in the household have already been exposed to the coronavirus. Again, it all depends on whether any individual cat is unfortunate enough to develop the mutated form of the FECV in their bodies. More research is being done to try to demystify this unusual and dreaded disease. Fortunately, while FECV is widespread, FIP is uncommon. Dr. Suzanne Hurst Kindness Animal Hospital 11035 S. Memorial 918-970-4300 drhurst@kindnessoftulsa.com |
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