PLEASE NOTE: This FAQ is dated 1995. There are no plans to update this reference. I believe the materials to still be useful to cat owners, but I recommend you do an Internet search, such as at on Feline Infectious Peritonitis to gather more current information. A good place to start is



The main author of this FAQ is Erin Miller []. However, this FAQ could never have been written without the information, editing, re-writing and general encouragement of Norman Auspitz [L13264%M9RSCS.GESNINET@GE1VM.SCHDY.GE.COM]. Also thanks to Lorraine Shelton [] for her advice and references.

The purpose of this FAQ is to answer frequently asked questions about Feline Infectious Peritonitis (FIP), which is one of the most difficult diseases in the feline community today. This FAQ is divided into two parts, the first is general information about the disease, and the second is about management of FIP in a multi-cat and cattery environment. The sources for this FAQ are listed at the end, as well as some additional recommended readings. Recently an excellent source of information on FIP has become available on the WWW as well. This article is much more technical and many cat owners may find it much more dense than this FAQ.



I want to point out first and foremost that I am not a veterinarian, nor even a person who has training in animal science such as a veterinary technician. I am a graduate student of physical anthropology, and an ailurophile. My goal with these FAQs is to take information from the medical literature and convey the parts that are most useful to the average cat owner and translate them into general terms that are easy to understand. I attempted to keep the FAQ as untechnical as possible, but unfortunately with such a complex disease that becomes very difficult. I hope this prooves to be of some usefulness. Also keep in mind that this disease is one of the most controversial subjects in feline health care. This is not a definitive guide to FIP, but only an attempt to compile the most current information. Ideally the reader of this FAQ should use this as a starting point when discussing FIP with their veterinarian. Vets and breeders will hold a wide variety of opinions on this disease, some of which may be based on current information, some of which may be based on hearsay and anecdotal evidence. You can only do your best to become as educated as possible and make your decisions on the course of treatment or preventive care. Always remember, your cats is YOUR responsibility, and no one, not your vet, not a breeder, not a friend-who-knows-everything-there-is-to-know-about-cats, nor the writer of an internet FAQ can force you do take an action that you don’t feel comfortable with. Do what you think is best for your cat. Period.



To begin and unfortunately in sum: There is NO effective treatment, there is NO diagnostic test, there is NO way to positively identify asymptomatic carriers (cats which shed the virus, but do not themselves show outward signs of illness), the incubation time is UNKNOWN, NO one is 100% sure of how it is spread between cats, and there is NO proven effective way to control its spread in a multi-cat household or cattery. So what is known? Read on.

PART I: General Information about FIP

I’ve heard FIP is like AIDS. Can I catch AIDS or anything else from it?

    • People often use the “it’s like AIDS” phrase to describe a number of illnesses in the animal (and human) community with the idea that most people know so much about AIDS that this analogy is useful. Unfortunately most people don’t know much about AIDS and the resulting effect is to scare people out of their wits and have them dump their cats or dogs at the nearest pound because they are so deathly afraid of catching AIDS from them. The ONLY similarity between FIP, FIV (Feline Immunodeficiency Virus) and FeLV (Feline Leukemia Virus) to HIV (which is believed to cause AIDS) is in their genetic makeup. All are RNA (as opposed to DNA) viruses, and FeLV and FIV (and HIV) are what are known as “retroviruses.” FIP is a type of “coronavirus” which makes it even less similar to HIV. To make it clear:


    • . See the


     for more information on retroviruses.


So what *is* FIP?

    • FIP is not caused by a retrovirus but by a type of coronavirus. One of the reasons FIP is such a problem for vets is because there may be no way to differentiate an FIP virus from certain other viruses. Current thinking is that FIP is caused by a mutation of the Feline Enteric Coronavirus (FECV). FECV is very common, and an FECV infection can have symptoms ranging from none, to flu-like with or without diarrhea. These are most common in kittens, but can occur in cats of any age. If the immune system is not functioning properly, a mutant FECV can become a more systemic infection that we call FIP. All FIP tests appear to react the same way to every type of coronavirus. So, if your cat had FECV as a kitten, it may cause the same reaction in the current test as true FIP (more on the tests below).

For the purpose of this FAQ, however, I am going to continue referring to an “FIP Virus” or “FIPV.” Just keep in mind that in fact, there may not be a difference between FIPV and FECV per se, just a difference in the way a cat’s immune system responds.

What are the symptoms of FIP?

    • FIP usually appears in one of two forms: Effusive (wet) and Non-Effusive (dry). It should not be thought, however, that there are two different FIP diseases. The results of the infection are a continuum on a scale, with the ‘wet version’ being one end, the ‘dry version’ being in the middle, and a ‘carrier’ being the other end (a carrier is where the cat has successfully fought off the disease but may still be able to expose other cats to the virus). The way this happens is when a cat is exposed to FIPV, if its immune system gives a poor response, the wet form will develop. If it gives a better response, the dry form will develop. In the best responses, the cat will not develop either form of FIP, although it may be a carrier of the FIP virus.


    • Wet


    • The wet form is more common, and more rapid in progression than the dry form. It is characterized by the abdomen and/or chest progressively but painlessly distending with fluid. If this occurs in the chest, respiratory distress can occur due to compression of the lungs and release of fluid into the airways. The lining of the affected cavity will be covered with white, fibrin-containing areas (fibrin is a protein that is the center of a blood clot), often on the liver and spleen. Certain types of lymph nodes may be enlarged. Other signs include jaundice; mild anemia; and gastrointestinal, ocular (e.g. eye ulcers or severe conjunctivitis), and neurological signs may also occur.


    • Dry


    The dry form is more rare (but appears to be becoming more common), and more slow in progression, often making diagnosis difficult. There is minimal fluid build-up, although weight loss, depression, anemia, and fever are almost always present. Signs of kidney failure, liver failure, pancreatic disease, neurologic disease or ocular disease may be seen in various combinations. Often the organs in question develop a characteristic pyogranulomatous inflammation (this is a chronic inflammation resulting in a thickening of the tissue and local accumulation of white blood cells). Unfortunately biopsy of these lesions is the only definitive way to diagnose this form of FIP and is usually done in the form of a post-mortem diagnosis.

What are the differences between FIP and FECV?

    • FIP is a disease. Normally the disease/virus relationship is simple, but this is not the case with FIP. FIP may be caused by many things, perhaps an isolated FIP virus (FIPV), perhaps a mutation of FECV, or perhaps there are multiples viruses which can all lead the the same disease complex known as FIP. There is little question, however, that the

most common

    •  cause of FIP is via FECV.


    • For the most part, FECV is limited largely to the intestines and is dealt with quite well by the cat’s immune system. However, as recent studies seem to indicate, FECV can mutate into FIP and, if the cat’s immune system is not operating properly, this mutant FECV stops being just an infection of the intestine and becomes the more systemic infection we call FIP.


    Thus, wherever you have FECV you could have FIP! Some cats never get FIP, but can continue to shed the FECV virus (now thought to be spread via the feces). The good news, however, is that since it seems that the dry form is becoming more prevalent, that cats are gradually becoming more able to resist FIP infection in general.

Is my cat at high risk?

    • If it comes in regular contact with other cats (i.e.: an indoor/outdoor cat), the answer is


     The lowest risk groups are indoor only, single-cat households. The higher the number of cats, the more risk of FIP. The higher the number of cats, the higher the titer test results (more on titers below). Single-cat households are generally free of all coronaviruses. FIP occurs in greatest incidence in cats between six months and two years old, although infections are high up to five years old. Of course the most susceptible group to catching FIPV are kittens because under the age of 16 weeks their immune system is very bad in general. Studies also show that poor nutrition, high stress levels or poor husbandry increase the likelihood of getting FIP. Outside exposure, exchanging of animals, especially kittens and young cats, highly inbred cats, and cats in actively breeding households increase the risk. Males and females are equally affected.

How is it transmitted?

    • Wouldn’t we all like to know! Seriously, there seems to be two schools of thought. One group (from Cornell-based publications and seminars) states that the spread is not known with certainty, but is believed to be by ingestion or inhalation of the virus. The other school of thought (from Dr. Pedersen and the UC, Davis based publications) believes that transmission is most prevalent when cats have close contact with other infected cats or their feces/urine. Both schools seem to feel that feces may play a large role in the method of transmission.


    Some studies suggest that viruses that can cause FIP can survive on dry surfaces (food/water bowls, litter boxes, human clothing, etc.) and can survive at room temperature probably up to 2 or 3 weeks. If this is the case, then the two schools of thought on methods of transmission may not be so far apart, especially given that litter can contain dust to which small particles of feces can adhere. Thus the virus can possibly be spread via litter dust on shoes or clothing or etc. making it behave as if it were an airborne virus!

If the virus can last so long on dry surfaces, what happens if I unknowingly come in contact with a cat with FIP? Can I give it to my cats?

    Most household soaps, detergents and disinfecting agents will kill the virus. Make sure you wash any part thoroughly that has come in contact with the cat (don’t forget your pants if the cat rubbed up against you). Bleach in a 1:32 solution is suggested for decontamination purposes.

Is there a test?

    • There is a test which will look for the presence of coronavirus antibodies in your cat’s blood. If your cat has been exposed to a coronavirus, ANY coronavirus, its immune system will build up antibodies to it, and the titer tests for the level of those antibodies in the blood. But it does not distinguish between antibodies made specifically against FIP, or FECV, or any other coronavirus. A positive titer means only that your cat has created antibodies (therefore been exposed to) SOME form of coronavirus. The higher the titer, the more antibodies the cat has created.


    • As if there were not


    •  problems with the coronavirus test, there is no uniformity between different labs. One cannot compare results from one lab to another. Some labs just specify positive or negative if the results are above or below a given titer (often these labs do not even specify the titer). There are no standards for setting up a lab, there is no regulatory body that oversees them, and no requirement for validation of test results. It is also possible for a cat which has received the vaccine (more below) to have enough antibodies to appear on the titer test. To top it all off, false positives occur in up to 30% of the tests. In sum:


    • There are some clinical indicators which your vet may discuss with you if s/he suspects that a cat has FIP, particularly if it is showing likely symptoms. Some blood tests can help your vet pinpoint FIP as a cause for your cat’s condition, this includes looking for a high amount of gamma globulin proteins and a low amount of albumin proteins in the blood.


    There has also been talk of a polymerase chain reaction (PCR) test, in the hopes that it can tell the difference between FIP and other coronaviruses. Significant scientific studies have yet to be concluded on this method. However, given that the most common way of a cat coming down with FIP is via the mutation of FECV, this test may have little or no value in the great majority of cases.

What about the vaccine?

    • There is a vaccine available, but it is controversial and some vets do not recommend it, although others highly encourage it. The manufacturer’s tests state that it has an efficacy rate (protection rate in this case) of 69%. Cornell Feline Health Center then did a study which said the vaccine failed to show any protection, and that it accelerated the disease in 52.5% of exposed cats. However, this study used a different challenge virus strain and the route of administration was different than the manufacturer’s tests. The ‘real-life’ significance of this has not yet been determined, neither Cornell nor the manufacture has received reports from the field of abnormally high numbers of cats which get the disease as a result of the vaccine. However, this study has caused a lot of people to swear-off the vaccine.

It really is between an individual cat owner and their vet to determine the whether or not to vaccinate based on the best information available at the time.

So are these the only test results?

    • Well, Cornell concluded from the above that vaccine efficacy in a laboratory setting is highly dependent on the challenge. It offers protection at low challenge doses, none at higher doses. The problem is, no one knows what the “real world” dose level is.

Another problem is that there are actually two strains of FIPV. Just as there are many different flu strains or cold strains which cause you to get sick several different times with the flu or a cold, because each time you catch a different strain for which you aren’t already immune. Type I strain of FIP is believed to be the most prevalent in the “real world” but it is the most difficult to reproduce in a laboratory. Type II is easier to reproduce, but not as prevalent outside. It is not known how effective a vaccine against one type will be against the other type.

So, while some of the studies have found the current vaccine effective against the Type II strain of FIP, there is no evidence either way as to if it will work against the Type I strain.

So that is Cornell’s opinion, are there any other points of view?

    The consensus arrived at the seminar sponsored by the Winn Foundation on FIP/FECV is that the enhanced disease effect is a laboratory phenomenon, especially since that study by Cornell only used seropositive cats in the first place.

What is a seropositive cat?

    • Some cats test positive on the coronavirus titer test, some do not. Those which have never been exposed to ANY form of coronavirus are called “seronegative.” Those which have been exposed to some form of coronavirus are called “seropositive.” The Winn Foundation-sponsored research felt the Cornell study was flawed because it used cats which had already been exposed to some form of coronavirus (were “seropositive”) and then attempted to test the vaccine.


    This is not to be confused with the terms “FIP negative” and “FIP positive” which are used by many labs to indicate that the coronavirus titer is less than (negative) or more than (positive) some predefined threshold level.

Have there been any more recent studies?

    • Yes. In another, recent study cats were tested in the same manner as in the vaccine manufacturer’s tests. At the end of an 8-week period, 30% of cats vaccinated, and 60% of the controls demonstrated FIP-positive conditions from tissue examinations. This demonstrates a 50% “preventable percentage.”


    Another recent field trial ran for 16 months using 500 cats in a no-kill shelter with endemic FIP. The fact that this is a shelter makes it a different makeup than a cattery (and some multi-cat households) because the average age of a cat was approximately 2 years old, and there were no kittens under 16 weeks old. However ALL cats tested were seronegative prior to exposure in the shelter. During the time of the study, 0.8% of the vaccinated cats died and 3.25% of controls died of FIP. [This is statistically significant at p=.048, which means that there is a 95.2% probability that this result is not random] So, for seronegative cats over the age of 16 weeks, this study shows a 75% efficacy rate. Vaccination after exposure (after a cat is already seropositive) is not likely to be helpful in preventing the disease.

So what does this all mean?

    • In sum, if you know your cats are seronegative, and they are older than 16 weeks, the vaccine is recommended by both the Cornell Feline Health Center and the consensus reached at the Winn Foundation sponsored FIP/FECV seminar. If your cat is already seropositive, there is not much evidence that the vaccine will help.

The vaccine will be more of a help when

      • the manufacturers demonstrate its effectiveness against the Type I strain of FIP
      • it is shown to be effective in seropositive cats, and
      • it could be shown to be safe and effective for kittens under the age of 16 weeks.

However, it appears that there is work being done to develop a FECV vaccine. Preventing FECV infections in the first place, and thus preventing FECV from mutating into FIP, might turn out to be another technique in trying to protect against FIP.

My vet believes that my cat has FIP, what is the best thing to do?

    Usually by the time the vet is able to pinpoint FIP as the cause of your cat’s condition, the cat is pretty far along. So long as your cat is in pretty good shape, not in any pain or discomfort, there is no reason to euthanize it. Even if your cat is happy and healthy, however, you MUST make sure you keep it indoors and away from other cats. If you feel that this will be too great a compromise on its quality of life, it is better to euthanize it. Since the cause of transmission is not known, by allowing your FIP+ cat outside, you could cause numerous other cats to become ill, and even further spread the disease. But please keep your cat’s welfare foremost in your mind. When its systems begin to fail, when it is in obvious discomfort, you are only making things worse by delaying the inevitable. Keep him or her as happy and as comfortable for as long as possible, that is unfortunately the only solution at this point.


PART II: Multi-Cat Household/Cattery Management

I have a lot of cats, what can I do to keep the risk of FIP down?

    • Limit the number of new cats and isolate each for at least one month, preferably two. I know it sounds like a long period of time, but consider the alternatives! You could lose every cat in your household. During the one month’s time period, make sure you watch carefully for signs of illness. You should give the coronavirus titer test at the beginning and the end of the quarantine period, and the titer should decrease over that time period.


    • Scoop the litter box daily, discard the rest of the litter weekly and disinfect the boxes with a 1:32 solution of bleach. The area around the boxes should be swept and disinfected, there should be at least one box for every two cats in the household. Again, weekly discarding of the scoopable litter may seem like a waste, but so far the ONLY thing the sources agree upon with regard to transmission is that it is definitely transmitted through the feces, if nothing else. In the words of one breeder: “It cost me approximately $3,000 in veterinary and laboratory services to diagnose the incidence of FIP in my cattery, test and retest (and retest) all of my cats. Believe me it is FAR less expensive to discard the litter” (Polli, p. 81). If your cats have long hair and fecal matter tends to stick to the britches, this hair should be kept clipped short.


    Change food and water daily, disinfect the bowls weekly. Do not mix the bowls all around the house, keep the same set of bowls with the same cats, and keep the same set of litter boxes with the same cats.

What if one of my cats if pregnant?

    • It is suggested that queens be completely isolated from other cats (isolated in its own room, not its own cage within a room). This room should be empty for one week prior to placing the queen there, and should be disinfected with a 1:32 solution of bleach. The queen should be placed in the isolation room 10-14 days prior to delivery. All bowls and litter boxes should be used exclusively for that room, and not interchanged with any others. You should disinfect your hands when entering and leaving the isolation room. If possible, you should even try to have separate clothing, such as a smock and slippers which are restricted to the isolation room to decrease risk.


    • If the queen is not seronegative, you may want to consider an early weaning program. The queen should be removed from the kittens at age 4-6 weeks and never returned. During the first 4-6 weeks of a kitten’s life, it gets its antibodies from their mother, therefore they are immune to anything she may be shedding. After that time period, they start making their own antibodies. If the queen is a carrier of coronaviruses, she can shed FECV to the kittens, and they are most likely to become infected during that time period. Regardless of whether the kittens are weaned early and isolated from the mother, they should be kept isolated from all other cats in the household. In addition to minimizing the risk of the kittens developing FIP, the risk of exposure to other viruses and diseases will be reduced.


    Kittens should be raised in complete isolation from the queen and all other cats/kittens in the household until they leave the cattery. If the kitten is to be kept in the cattery, it should be isolated for 16 weeks, and then the FIP vaccination series should be completed before allowing the kittens to interact with the other cats.

Is there any evidence for this?

    A 1992 study found the following: 400 kittens were divided into 41 household with various FIP histories. In one group the kittens were allowed to freely associate with all the cats. In a second group the kittens were isolated only with their mother. In the third group, the kittens were isolated by themselves starting at age 2-6 weeks. Only in this last group did all of the kittens remain seronegative for any/all coronaviruses.

That sounds absolutely ridiculous! Who would go through all that?

    Nobody says a breeder HAS to do any of this. These are merely the precautions currently recommended by the Cornell Feline Health Center and the recommendations which came out of the Winn Foundation sponsored Seminar on FIP/FECV. It is an option kitten buyers can use in determining which breeder to select if they so choose, but it is by no mean mandatory.




  • Polli, Leigh. “Highlights from The Winn Feline Foundation International FIP/FECV Workshop.” Cat Fanciers Almanac, 11(8), December 1994.
  • Richards, James R. DVM. “Management of Coronavirus Infections in Catteries and Multicat Households.” Comprehensive Seminar for Cat Breeders Cornell University School of Continuing Education and Summer Sessions.
  • Siegal, Mordecai (ed.) Cornell Book of Cats: Comprehensive Medical Reference for Every Cat and Kitten. New York: Villard Books, 1991.

Additional Readings:


  • Addie, D.D. and Jarret, O. “A Study of Naturally Occuring Feline Coronavirus Infections in Kittens.” Vet Record Feb. 15, 1992.
  • Barlough, J. E. and Stoddart, C.A. “Feline Infections Peritonitis.” Cornell Feline Health Center Information Bulletin 6, 8/84.
  • Olsen, C, and Scott, F.W. “Feline Peritonitis Vaccination – Past and Present.” Feline Health Record Topics for Veterinarians 6(20), Spring 1991.
  • Scott, F.W., Corapi, W.V., and Olsen, C.W. “Evaluation of the Safety and Efficacy of Primucell FIP Vaccine.” Perspectives on Cats, Fall 1992
  • Richards, J.R. “FIP: The Challenge Continues.” Cat Fancy 36(5): May 1993.Papers in Feline Practice Volume 23, Number 3. May/June 1995 
  • Addie D.D., Jarett O. Control of Feline Coronavirus Infections in Breeding Catteries by Serotesting, Isolation, and Early Weaning. Feline Practice 23(3), 92-95, 1995.
  • Addie D.D., Toth S., Murray G.D., Jarett O. The Risk of Typical and Antibody Ehhanced Feline Infectious Peritonitis Among Cats From Feline Coronavirus Endemic Households. Feline Practice 23(3), 24-26, 1995.
  • Fehr D., Holznagel L., Bolla S., Lutz H., Hauser B., Herrewegh A.A.P.M., Horzinek M.C. Evaluation of the Safety and Efficacy of a Modified Live FIPV Vaccine Under Field Conditions. Feline Practice 23(3), 83-88, 1995.
  • Gerber J.D. Overview of the Development of a Modified Live Temperature- Sensitive FIP Virus Vaccine. Feline Practice 23(3), 62-66, 1995.
  • Herrewegh A.A.P.M., Egberink H.F., Horzinek M.C., Rottier P.J.M., de Groot R.J. Polymerase Chain Reaction (PCR) for the Diagnosis of Naturally Occurring Feline Coronavirus Infections. Feline Practice 23(3), 56-60, 1995.
  • Hickman A., Morris J.G., Rogers Q.R., Pedersen N.C. Eliniation of Feline Coronavirus Infection From a Large Experimental Specific Pathogen-Free Cat Breeding Colony by Serologic Testing and Isolation. Feline Practice 23(3), 96-102, 1995.
  • Horzinek M.C., Herrewegh A., de Groot R.J. Persepectives on Feline Coronavirus Evolution. Feline Practice 23(3), 34-39, 1995.
  • Hoskins J.D., Taylor H.W., Lomax T.L. Independent Evaluation of a Modified Live Feline Infectious Peritonitis Vaccine Under Experimental Conditions (Louisiana Experience). Feline Practice 23(3), 72-73, 1995.
  • Hoskins J.D., Henk W.G., Storz J., Kearney M.T. The Potential Use of a Modified Live FIPV Vaccine to Prevent Experimental FECV Infection. Feline Practice 23(3), 89-90, 1995.
  • Kass P.H., Dent T. The Epidemiology of Feline Infectious Peritonitis in Catteries. Feline Practice 23(3), 27-32, 1995.
  • McArdle F., Tennant B., Bennett M., Kelly D.F., Gaskell C.J., Gaskell R.M. Independent Evaluation of a Modified Live FIPV Vaccine Under Experimental Conditions (University of Liverpool Experience) Feline Practice 23(3), 67-71, 1995.
  • Pedersen N.C. An Overview of Feline Enteric Coronavirus and Infectious Peritonitis Virus Infections. Feline Practice 23(3), 7-20, 1995.
  • Pedersen N.C. The History and Interpretation of Feline Coronavirus Serology. Feline Practice 23(3), 46-51, 1995.
  • Pedersen N.C., Addie D., Wolf A. Recommendations From Working Groups of the International Feline Enteric Coronavirus and Feline Infectious Peritonitis Workshop. Feline Practice 23(3), 108-111, 1995.
  • Postorino Reeves N. Vaccination Against Naturally Occurring FIP in a Single Large Cat Shelter. Feline Practice 23(3), 81-82, 1995.
  • Richards J.R. Problems in the Interpretation of Feline Coronavirus Serology (Specificity vs. Sensitivity of Test Procedures). Feline Practice 23(3), 52-55, 1995.
  • Scott F.W., Corapi W.V., Olsen C.W. Independent Evaluation of a Modified Live FIPV Vaccine Under Experimental Conditions (Cornell Experience). Feline Practice 23(3), 74-76, 1995.
  • Scott F.W., Olsen C.W., Corapi W.V. Antibody-Dependent Enhancement of Feline Infectious Peritonitis Virus Infection. Feline Practice 23(3), 77-80, 1995.
  • Vennema H., Poland A., Hawkins K.F., Pedersen N.C. A Comparison of the Genomes of FECVs and FIPVs and What They Tell Us About the Relationships Between Feline Coronaviruses and their Evolution. Feline Practice 23(3), 40-44, 1995.
  • Weiss R.C. Treatment of Feline Infectious Peritonitis With Immunomodulating Agents and Antiviral Drugs: A Review. Feline Practice 23(3), 103-106, 1995.
  • Wolf J. The Impact of Feline Infectious Peritonitis on Catteries. Feline Practice 23(3), 21-23, 1995.

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