Start by testing your breeding queen(s). Knowing the FCoV antibody titer and virus shedding status of your breeding queen is absolutely essential.

Importance of testing the queen for FCoV antibodies:
Some breeders are reluctant to blood test a pregnant queen for FCoV antibodies because it may stress her. Some will have tested the queen prior to mating, although bear in mind than an uninfected queen could become infected at stud, so her status may have changed by the time she kittens. It is not a good idea to stress the queen immediately after kittening, as she may then reject the kittens, so the best time to antibody test is 2-4 weeks after giving birth.

Knowing the queen’s antibody status is very useful for the following reasons:
If the queen has an antibody titer of zero (by an immunofluorescent antibody test at a reputable laboratory), then she is not shedding the virus, and is safe to leave her with her kittens as long as you wish, no need to early wean! Though isolation of the queen and kittens together is essential unless all your other cats are also FCoV antibody titer zero.
The lower the queen’s antibody titer, the fewer protective antibodies the kittens will receive in their mother’s milk, so you may want to consider testing her feces to see if she is shedding virus and if she is, to err on the early side of weaning the kittens (i.e., 4 or 5 weeks of age rather than 5-6 weeks).
The higher the queen’s FCoV antibody titer, the more protective antibodies the kittens will receive in their mother’s milk, but also the chances of her shedding FCoV are higher. Around one in three cats with FCoV antibodies is shedding the virus at any given time; the higher the FCoV antibody titer, the greater the probability of virus excretion.

Should you test the kittens?
It is inadvisable to FCoV antibody test kittens younger than ten weeks old: kittens under ten weeks of age may be infected, but some are too young to have produced antibodies of their own. Most kittens can make antibodies by ten weeks of age, so 10-16 weeks is the best time to test. Very young kittens may give a positive result not because they are infected, but because they have antibodies from their mother’s milk.

Stud cats and FCoV: stud cats should be tested every year for FCoV antibodies along with their routine FeLV and FIV blood tests.

There is some evidence that susceptibility to developing FIP has a hereditary component, so if your stud has fathered many kittens who have developed FIP, you may want to think seriously about neutering him and keeping him as a pet or rehoming him.

The FCoV antibody positive stud cat:
If your cat has been an active stud cat for many years, the chances are high that he will have antibodies against FCoV. If he has been exposed to FCoV for more than two years, it is unlikely that he will develop FIP now, except perhaps when he gets into old age and his immune system begins to wane, or some other thing suppresses his immune system. If he is a young stud and has only recently been infected with FCoV, then minimize the stress and optimize his nutrition to keep his chances of developing FIP to a minimum.
It is important in this cat to distinguish between the two phenomena:

The FCoV antibody positive stud cat has been exposed to the virus but may not be actively infected (i.e., he may not currently be excreting virus in his feces). About one cat in three with FCoV antibodies shed the virus at any given time, although the higher the antibody titer, the greatest the chances that the cat is shedding the virus (you can find out if he is shedding the virus by sending a fecal sample to a veterinary laboratory for FCoV RT-PCR).
The FCoV RT-PCR positive stud cat is quite definitely actively infected and is excreting virus in his feces, although in a few weeks or a month, it is very likely that he will stop doing so.

Your choices are between carrying on as before, with all the attendant risks, or beginning regular testing and introducing controlled mating and hygiene precautions to prevent re-infection of your stud cat once he stops shedding the virus. A small number of cats become FCoV carriers – shedding virus for all their lives. In that case, your choices would be between stop using him as a stud or controlled mating only.

The important thing is HONESTY if he is an open stud, please DO NOT be a source of infection for another cat breeder. If you explain your situation openly and honestly, it is surprising how understanding people will be, and more people will come to you to use your stud because you are trustworthy and knowledgeable about FCoV and FIP.

The FCoV antibody negative stud cat
An FCoV free stud is something to be very proud of! If your whole household is FCoV free, then the only risks of him becoming infected are:
by mating him with an FCoV infected queen;
by introducing into your house an untested, or improperly tested, FCoV-infected cat;
by taking him to a cat show.

Controlled mating
A relatively safe way of mating an FCoV infected cat to an FCoV free cat is by controlled mating – that is where the calling queen is left with the stud cat only for a few hours until mating takes place and importantly the uninfected cat does not get in contact with the litter tray of the infected cat.
If it is the stud cat who is infected and the queen who is negative, the queen would NOT be put into his pen, which is likely full of virus, instead both cats would be put into an area which had previously been thoroughly scrubbed, disinfected and preferable steam cleaned. If the queen is positive and the stud is negative, she can be put into his pen, as long as she doesn’t defecate there.
If your cats are long-haired, trim their trousers, to reduce the chances of feces getting trapped on them. Please keep in mind FCoV can cause diarrhea, which makes it more likely for the fur to get contaminated by feces.

We are counting on you.
All of us at EndFIP® want to impart worldwide awareness and understanding of FCoV and respect for the seriousness of FCoV infection, and we need your help by getting more informed and shared your knowledge with other breeders on how to prevent FCoV infection of kittens. If you are thinking that it can’t be done or that it will be a very time consuming and costly process, please know that it can be achieved and your expenses of FCoV eradication will be rewarded and recouped in the following ways:
You will not have to replace kittens who have died of FIP.
Your kittens will not develop diarrhea at 5-7 weeks of age, so fewer veterinary bills
Your kittens will be evenly sized, and you will almost never have runty kittens.
You will not be accused or sued/prosecuted for selling a kitten who later develops FIP.

In addition to all of the above, you will have the pleasure of knowing you produced strong and healthy kittens and your cattery will be recognized as one of the few FCoV free catteries found worldwide which is something to be extremely proud of and something many people will consider when thinking about buying a pedigree cat. Pet guardians are becoming much more knowledgeable about FCoV and FIP, and it is only a question of time before they will demand proof the kittens are FCoV free before purchasing. The time to ignore and disregard FCoV infection is coming to an end.

Do you want to learn in an easy and fun way how to prevent the virus which causes feline infectious peritonitis (FIP) from infecting your cats, watch this video.