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Feline Infectious Peritonitis FAQ
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 www.google.com on Feline Infectious Peritonitis
to gather more current information. A good place to start is
The main author of this FAQ is Erin Miller [email@example.com]. 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 [Lorraine_Shelton_at_HYL101@ccmailgw.mcgawpark.baxter.com]
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?
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: THERE IS
ABSOLUTELY NO WAY TO CATCH AIDS FROM A CAT, NO MATTER WHAT FELINE
DISEASE THAT ANIMAL MAY HAVE. See the FeLV FAQ 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.
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.
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 YES! 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
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 enough 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: DO NOT PLACE MUCH CREDENCE IN THE TITER TEST,
AND UNDER NO CIRCUMSTANCES SHOULD A CAT BE EUTHANIZED BASED SOLELY ON
THE RESULTS OF THE TITER TEST.
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
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
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,
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
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
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
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
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
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,
This article is Copyright (c) 1995 by [ firstname.lastname@example.org]
reserved, please ask about redistribution.
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