Frequently asked questions about FIP

What is FIP?
How do cats contract FIP?
What about outbreaks of FIP within a group of cats?
What are some of the signs of FIP?
What are some of the tests that are used by veterinarians to diagnose FIP?
How can you distinguish between FIPV and FECV infections in a cat?
How do I identify cats which are shedding FECV?
How can I cure my cat that has been diagnosed with FIP?
A cat in my house died of FIP and I have other cats. I am worried that they will get FIP. What do I do now?
How do I lower the incidence of FIP in a large multiple cat household?
If a cat died of FIP, how long should I wait before I get another cat?
Did my cat get FIP from the cattery, shelter, or pound?
How do we interpret FIP titers?
How can I prevent FIP in the future?
Should I vaccinate my cats?
Can members of my family get FIP?
I’ve tested all of the cats in my home and they all have "0" titers (not low but actually 0 titers). How can I safely introduce a new cat?

What is FIP? | top
Feline Infectious Peritonitis (FIP) is a fatal disease of cats. The FIP virus (FIPV) is a genetic mutant of a more common and benign virus of the intestines of cats, Feline Enteric Coronavirus (FECV). The mutation that leads to the FIPV is relatively minor, but allows the virus to grow in cells other than those that line the gut. These new cell hosts are called macrophages, and because macrophages wander throughout the body, the mutant virus is also spread from the gut to other organs.

How do cats contract FIP? | top
There are two ways a cat may contract FIP: 1. From other cats with FIP. This scenario is probably uncommon. Even if a cat has FIP, it probably has or had FECV first, and could be shedding either FECV or FIPV in its feces. However, FIPV usually stays in tissues outside of the gut (such as the brain or kidneys), while the FECV is lives in the gut lining cells. If a cat with FIP sheds a coronavirus, it is usually of the FECV type. 2. From a mutation during FECV infection. This is the more common occurrence. Mutations from FECV to FIPV occur in about 5% of kittens with FECV. The incidence of the mutation is probably lower in older cats.

What about outbreaks of FIP within a group of cats? | top
Outbreaks take one of two forms: Sporadic FIP cases are usually sporadic, with an average loss of 5% or fewer of cats in a home or cattery dying. Sporadic disease indicates that FECV is present in the population constantly. Epidemic. Epidemics of disease affecting 10-50% of the younger cats occur rarely. After the initial outbreak, epidemics are usually replaced by sporadic disease within 6-12 months. We can’t predict what form of disease will occur in a given home, however, if cats are exposed to FECVs, there is always a risk that FIP may occur.

What are some of the signs of FIP? | top
The most common signs of FIP in young cats are cyclic, antibiotic non-responsive fever, lethargy, and failure to grow. Additional signs depend on what form the disease takes, i.e., wet or dry FIP. Cats with the wet form of FIP develop a yellow fluid with high protein content in their chest or abdomen. This fluid may cause breathing problems or abdominal distention. The dry form is associated with masses (granulomas) on the kidneys, mesenteric lymph nodes, and in the brain and eyes. Cats with dry FIP usually have ocular or neurologic signs.

What are some of the tests that are used by veterinarians to diagnose FIP?
The diagnosis of FIP should be based on the veterinarian’s clinical observations which include a taking a history of the animal, physical exam, and laboratory findings (including a titer). The diagnosis is seldom made on a single test. Complete blood counts (CBC), titer, total protein, and a good physical examination are recommended. CBC abnormalities include elevated total protein (mainly globulin), increased numbers of total white blood cells and neutrophils, and decreased numbers of lymphocytes. The fluid is characteristic for FIP, being yellowish, sticky or mucinous, high in protein, and containing numerous neutrophils and macrophages. Biopsies of masses in cats with dry FIP show granulomatous inflammation. There is only one way to confirm a diagnosis of FIP: that is to identify the FIPV in biopsies of masses or at necropsy. The most accurate technique to detect virus is by a procedure called "immunohistochemistry" and is performed on biopsy tissues. This test will show the presence of the virus within macrophages in body fluids or granulomas. New RNA-level tests, such as PCR, cannot differentiate the FIPV from the FECV, but may be useful in odd anatomical locations, such as the brain (where FECV does not invade).

How can you distinguish between FIPV and FECV infections in a cat? | top
FIPV infection almost always makes the cat ill and is invariably fatal over a period of weeks or months, while FECV infection is usually not apparent and, if no mutation occurs, clinically inconsequential. Cats infected with FECV produce antibodies that cross-react with FIPV because they are virtually the same virus. All cats that have FIP have antibodies to both FIPV and FECV. Therefore, the diagnosis of FIP, by antibody tests, in a cat that is healthy or has clinical signs unlike FIP, is a serious error. In an attempt to improve on serology, a polymerase chain reaction (PCR)-based test is being used by many veterinarians. This test suffers from the same limitations as serology and should not be used as the sole basis for diagnosing FIP. Ultimately, FIPV infection is distinguished from FECV infection by the presence of abnormalities consistent with FIP. This includes the history (younger cat originating from large multi-cat environment), veterinarian’s physical findings (fever, fluid in body cavities, masses in abdomen, ocular or neurologic disease), coronavirus antibody titer, results of complete blood count, laboratory analysis of abdominal or chest fluids, biopsies of masses, and immunohistochemistry (see above).

How do I identify cats which are shedding FECV? | top
The most effective way to identify cats shedding FECV is PCR. From 40-60% of cats in large multiple cat environments shed virus in their feces at any given time. About 20% will shed virus persistently, while 20% will be immune and not shed virus. The remaining 60% will shed intermittently depending on their particular pattern of infection and re-infection. Unfortunately, this test is relatively expensive and the nature of the virus shedding pattern can only be determined following repeated monthly testing over a period of 6-12 months. Moreover, a positive fecal PCR only tells you if a cat is shedding FECV, and not whether is has FIP or will develop FIP in the future.

How can I cure my cat that has been diagnosed with FIP? | top
Virtually every cat with confirmed FIP dies. The use of immunosuppressive drugs such as corticosteroids or cyclophosphamide may slow disease progression, but does not alter the outcome. Many veterinarians are using immunostimulants of various types (immunoregulin, interferon, acemannan, etc.) to treat cats with FIP. This type of therapy is often very costly and also does not change the outcome of the disease. We recommend that people provide supportive therapy (rest, good nutrition, lack of stress) for as long as the cats are reasonably healthy. Once disease signs become debilitating and weight and appetite decline, the owner must be prepared for the reality that the cat is dying.

A cat in my house died of FIP and I have other cats. I am worried that they will get FIP. What do I do now? | top
There is not a lot you can do; by the time one cat is sick, the remaining cats have already been exposed to the same FECV. Fortunately, cats that have FIP do not usually shed the FIPV from their bodies. If they do shed virus, it is of the FECV type. If the cat that died is not a full-sib littermate of any of the remaining cats and this is a typical home with 2-6 cats, the chances of any other cats dying of FIP are very remote.

How do I lower the incidence of FIP in a large multiple cat household?
There are three ways that FIP losses can be decreased: 1.Decrease the severity of FECV infection, by better husbandry. Maintain as high a degree of general cleanliness as possible and clean litter boxes frequently. 2.In the case of pedigreed catteries, use breeders that have a higher genetic resistance to FIP. Toms that sire litters that develop FIP should not be used for breeding purposes. Although both toms and queens possess the same favorable or unfavorable genes, the tom has the greatest influence on the incidence, because he has the most offspring. 3.Reduce the numbers of cats, especially kittens, in the environment. Keep cats isolated into smaller groups. Simple isolation does not seem to be effective in reducing FECV infection, primarily due to the ease with which FECV is carried/tracked from one location to another on clothes, shoes, dust, cats’ fur, etc. Reducing the numbers of cats to 5 or less is the most important factor in controlling FIP. FECV infection maintains itself by constantly infecting and re-infecting the same cats. If the numbers of cats are high, there will never be a time when infected and recovered/susceptible cats do not coexist. When the numbers of cats drops to 5 or less, it is very difficult for the virus to sustain itself. We recognize that for cat breeders and animal shelters reducing numbers may not be feasible, and that the answer for future control of FIP is more research and effective vaccines.

If a cat died of FIP, how long should I wait before I get another cat? | top
People typically wait at least 1 month. Vacuum and clean the house as thoroughly as possible. Litter pans, bowls, scratching posts, should be cleaned with hot soap and water and rinsed in a 1:32 dilution of household bleach. Porous or fragile objects that cannot be properly cleaned should be discarded. Normal exposure to air and sunlight will usually destroy coronaviruses within 2 weeks. However, the virus can survive longer within dried litter and feces, hence the need for cleaning.

Did my cat get FIP from the cattery, shelter, or pound? | top
Two thirds to three-fourths of all cases of FIP occur in cats 3-18 months of age that originate from pedigreed catteries, shelters, and large multiple-pet cat homes. Therefore, if you get a new kitten from such an environment, and it is the only cat in your home, the chances are high that it had the infection at the time it was obtained. If you introduce a new cat into a household containing numerous other cats, it is virtually impossible to pinpoint the source of the infection.

How do we interpret FIP titers? | top
Good laboratories will test the serum at dilutions starting at 1:25. If it is negative at 1:25, you can assume that the cat is truly negative. If the titer is positive at 1:25, good laboratories will further dilute the serum until it no longer tests positive. The dilution at which the antibody is still barely detectable is called the endpoint titer. This will be expressed as a number like 1:400, 1:600, 1:3200, etc. Unfortunately, many laboratories do not titrate serum in this manner, and only report titers that are 1:400 or above as positive. Cats with lower titers will be reported as negative. Since there are many cases of FIP in cats with titers lower than 1:400, you should try to find a lab that dilutes down to 1:25. Our Veterinary Medical Teaching Hospital offers this test; contact the VMTH Immunology Lab (530) 752-7373. Rising titers are less informative than they would be for other diseases, because cats with FIP and FECV both cycle up and down in titer level. Very high titers (>1:16,000) are strongly suggestive of FIP. Remember: Cats must be showing clinical signs of FIP as described in the literature (see section 5: clinical observations) in addition to having a titer. Virtually all cats in multi-cat facilities test seropositive and even if exposed to FECV, most cats will not get FIP.

How can I prevent FIP in the future? | top
At this time there is no sure way to prevent FIP. Our best suggestions are to: 1) reduce cat numbers (ideally to 5 or less), 2) eliminate chronic carriers, and 3) try to get cats from homes with few cats, and/or with absolutely no recent history of FIP, and always pick the healthiest, most vigorous kittens, not the runt.

Should I vaccinate my cats? | top
The present vaccine is only about 50% efficacious at best, but only under special conditions. The cats must be at least 16 weeks of age and coronavirus antibody negative. The efficacy of the vaccine in very young cats and in antibody positive cats is negligible. Unfortunately, cats that are at highest risk for FIP (e.g., pedigreed cattery and shelter reared cats) are inevitably exposed to FECV long before 16 weeks of age. This means that vaccination is least effective in cats that are at highest risk, and most effective in cats at lowest risk (i.e., pet cats from homes with one or two animals).

Can members of my family get FIP? | top
No, it is not a human disease.

I’ve tested all of the cats in my home and they all have "0" titers (not low but actually 0 titers). How can I safely introduce a new cat? | top
The new cat must also have a "0" titer, i.e., negative at a serum dilution of 1:25 or less.

Used with permission from the Winn Feline Foundation www.winnfelinehealth.org

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