One of us at Sarsenstone is an epidemiologist, a researcher
who specializes in disease prevention and control, so we can't resist
talking a little about how to prevent and control feline infectious peritonitis,
FIP. We also encourage you to ask your veterinarian any questions you may
have about FIP.
When you look at cattery ads and websites, you often see "We guarantee
our kittens free of feline leukemia and FIV." Sometimes you see guarantees
that kittens are free of ringworm and FIP, as well.
It is reasonable for a breeder to claim that her kittens are free of
feline leukemia and FIV. There are good screening tests for those diseases.
The tests are not perfect. No test is. But they are very, very good, about
as good as screening tests can get. If a breeder tests all new cats for feline
leukemia and FIV and does not allow the new cats to join her other cats
until she is sure they are negative for those diseases, and if she never
allows her cats to wander outdoors, she can be confident, and so can you,
that her kittens are leukemia and FIV-free.
Ringworm is more problematic. A breeder can reduce the risk of ringworm,
but cannot absolutely guarantee her kittens will be ringworm-free. The Wood's
lamp test for ringworm is only partially effective, and new breeding cats
may carry ringworm asymptomatically and go on to infect the kittens in
a cattery. Ringworm is particularly likely to break out if the cattery is
located where the weather is usually both warm and damp.
In this article, however, I am mostly going to talk about FIP. FIP should
not be confused with FIV. They are two entirely different diseases. There
is a good test for FIV, but there is no valid screening test for FIP and
no cure for the disease. FIP is nearly always fatal once symptoms have appeared,
so this is a huge concern.
Let me say it again.
Although some breeders advertise that they have tested their cats
for FIP or that their catteries are "FIP negative," those claims are meaningless.
There is no laboratory test that can guarantee that any cat is free of
FIP. There are several tests that have been developed for
FIP, but so far none has proved to be even a moderately good screening test.
In fact, the situation is so miserable that breeders can test every cat
and get negative results even in the middle of an FIP epidemic in
the cattery.* On the other hand, cats can have high coronavirus titers (the
coronavirus titer is one of the "tests" for FIP) when they don't have FIP
at all but instead are only fighting a harmless coronavirus, something that
could easily happen after a cat changes homes and encounters new but harmless
family "bugs." FIP testing is a complex area of veterinary medicine and not
all vets adequately keep up with developments in that area. Due to occasional
veterinary misinterpretation of "FIP tests," some cats have been euthanized
who had temporarily high but harmless coronavirus titers, cats who otherwise
might have lived long healthy lives.
So how can you tell whether the risk of FIP is low in a cattery?
Well, mainly by how clean it is, how happy the cats are, and how uncrowded
the cattery is. Having an uncrowded cattery with happy, unstressed cats
is very, very important. Breeders can use good cattery management to reduce
the risk of FIP. A cattery that is at low risk for FIP is one that has
only a few felines, especially young felines, on the premises at any given
time. The fewer, the better. There are reputable breeders who breed more
than a few litters per year and have excellent reasons for doing so, but
the fact is, the more adult cats are housed together and the more litters
are bred on the same premises in a given year, the higher the risk of FIP.**
The bug that causes FIP is one type of coronavirus from a family
of hundreds of harmless coronaviruses. The harmless coronaviruses, the
ones that do not cause FIP, are common as dirt, and research has shown
that in a multi-cat home they are nearly always present. Unfortunately, it
appears that at any given moment a harmless coronavirus may mutate into a
dangerous FIP virus. Currently, it is not possible to eliminate all types
of coronaviruses. That would be like trying to keep every mote of dust out
of a home, just not practical. FIP can therefore develop in any cat in any
home. In one published case, a pet cat living strictly indoors by himself
for eleven years developed FIP.
Fortunately, FIP does not often develop in adult cats. FIP most
often strikes at age 6 to 8 months, and it strikes somewhat often in kittens
up to 1 1/2 years old. Kittens are much more likely to develop FIP than
adults because kittens have immature immune systems (especially when they
are less than a year old). No one knows for certain why the big older kittens
develop FIP more often than the young babies, but it may be that FIP is
a complex disease that takes a long time to develop. It starts in very
young kittens, but the first symptoms are not seen until the kitten is
much older.
According to one recent estimate, even very well run catteries and
shelters may have something like 2 percent of their kittens develop FIP,
and virtually all of them that do will die of the disease. To put it another
way, it's virtually impossible to rescue cats or breed cats for any length
of time without eventually encountering FIP. Cases tend to occur in clusters.
That is, the cattery or shelter may go for several years without a single
case of FIP, then begin to have cases occur regularly, and finally FIP stops
appearing for another few years.
Whether or not a kitten gets FIP seems to depend primarily on
two things: (1) stress and (2) genetics.
To put it another way, the development of FIP depends on the strength
of the feline immune system. Stress impairs the immune system in most animals
and in humans. Very young cats under stress are more vulnerable to FIP
than other cats. Veterinary researchers have noticed that FIP frequently
strikes after a stressful event, such as changing homes, declaw surgery,
or after a period when the cat's beloved owner was out of town.
Cats that have inherited weak immune systems are also vulnerable
to FIP. In fact, researchers estimate that genetic factors account for
about 50 percent of the risk of FIP. Although the amount of inbreeding
in a cat's pedigree did not seem to predict FIP in one study, that may
be because of the study's limitations. In epidemiologic studies, the ability
to detect the cause of a disease will in part depend on how much variation
in exposure there is in the population studied. In plain English, if you
study a group of pedigreed cats, all of whom are actually fairly
inbred, they may not be different enough from each other for researchers
to detect a significant genetic difference in their risk of FIP. It can
appear as if genes don't matter when in fact they do.
This kind of research limitation is particularly likely if a
genetic predisposition to FIP is the result of dozens of genes (polygenes).
Experimental evidence points to the importance of genes
in designing the feline immune system and thereby affecting vulnerability
to FIP. In one study, for example, the ability of each cat to produce
interferon gamma seemed to determine whether the cat did or did not come
down with FIP symptoms and die. Interferon gamma is one of the tools the
immune system needs to fight certain types of disease.
At Sarsenstone Cattery, we think the evidence is strong enough
to take seriously. We have always had an extraordinarily low incidence of
FIP in our cats. In fact, we have never had a case of FIP occur in cats
or kittens living with us, including no unexplained deaths of cats or kittens,
and we only once in the history of our cattery have ever had a kitten develop
FIP after leaving us. That particular kitten developed FIP about 8 months
after he left, at age 11 months old. He was from the only litter we've ever
produced that had somewhat closely related parents. The mother of the kitten
was the half niece of the father; that is, the maternal grandmother of
the kitten was the half sister of the kitten's father. Perhaps that was
just bad luck, just random chance. Or perhaps it was the shared genes the
parents had that caused their kitten, just the one kitten out of a litter
of five, to have a weaker immune system and be more vulnerable to FIP than
our other kittens.
We will never know for sure. We neutered the father of the kitten;
he never sired another litter. The mother of the kitten had many litters
with other studs and never had any other offspring come down with FIP.
But it is just one more reason, out of hundreds of other reasons,
to avoid breeding closely related cats and, indeed, to actively search for
and import fresh bloodlines to expand the gene pool of our cattery and
of the breed as a whole.
For those of you who are looking for a purebred kitten or cat
to join your family, the bottom line is simple. If a breeder breeds long
enough, sooner or later that breeder will encounter a case of FIP in the
cattery. It's not a question of if; it's a question of when.
Good breeders can't completely prevent FIP. There is no such thing as an
"FIP-negative cattery." But breeders can make FIP a rare event via wise cattery
management.
Remember: There is no reliable test for FIP. However, you can
evaluate risk by looking at cattery conditions. Breeders with multiple
litters perpetually present and large numbers of cats crowded together
have a high-risk situation. A breeder with very few adult cats,
who raises only a few litters per year, and who keeps the premises immaculate
and the cats well fed and uncrowded and happy, has the lowest possible
risk of FIP. §
For more
information about FIP, we encourage you to visit the SOCKFIP website (click logo below),
where you can learn about the latest research at the University of
California at Davis and the war the cat fancy is waging against FIP. You may also want to consult
the excellent
article by Dr. Susan Little, a veterinarian who specializes in cats
and who also had breeding experience when she was younger. She knows more
than most vets about the theory and practical issues surrounding prevention
of FIP .
