Feline Infectious Peritonitis (FIP): an in-depth look.
Please note: this section is intended for individuals who want to learn more and have a deeper understanding of feline coronavirus and FIP. Basic knowledge of veterinary/scientific terms is needed to fully comprehend this section which was created for information purposes ONLY.
If you are a veterinarian, veterinary student, vet tech or hold any other type of position in the veterinary field, please visit Dr. Diane D. Addie’s website catvirus.com.
If you are a pet parent with a sick cat, please consult a qualified veterinarian IMMEDIATELY.
The authors exclude all liability whatsoever for any loss or damage arising out of the use of this website or reliance upon its content and STRONGLY advises anybody with veterinary-related questions to consult a qualified veterinarian. No responsibility can be accepted.
Main source of infection: Feces
The main mode of FCoV transmission is indirect – uninfected cats coming into contact with the feces of infected cats, usually by sharing a litter tray and also by microscopic fomite transmission, for example on poop scoops. Thus good hygiene practices are the single best way of controlling FCoV infection. There should be an adequate number of litter trays for the number of cats in a household: preferably one per each cat plus one. Placing litter trays away from food areas is a must and covered or flushing litter trays are the best designs to minimize infectious particles of litter being blown about. Choosing a non-tracking cat litter (such as World’s Best) and using specialized mats which further reduce cat litter tracking is highly recommended. Litter trays should be de-clumped at least once daily and cleaned and disinfected with household bleach (1:32 bleach and water solution) at least once a week.
Prevent infection of uninfected cats by testing before introduction/mating
Cats can be kept FCoV free only by preventing them coming into contact with fecal matter from FCoV infected cats. One a cat is FCoV antibody negative, any new cat should be antibody tested BEFORE being introduced. FCoV antibody positive pedigree cats can still be mated but should only be mated with other FCoV seropositive cats and their kittens should be early weaned and isolated to prevent them becoming infected (please see below).
FCoV free households should introduce only FCoV seronegative cats. Seropositive cats should be quarantined and re-tested every 3-4 months until they become seronegative. For these measures to effective, it is essential that a reliable FCoV antibody test be used and that the first dilution used by the Laboratory is around 1:10. Laboratories using a cutoff of 1:100 will miss some cats shedding FCoV. Please consider sending the samples to reputable Laboratories and avoid some of the most commonly used test with dilutions of 1:400 and higher. Detection of virus in feces of healthy cats by RT- PCR may be used as an adjunct to FCoV serology.
Prevention of FCoV infection, and therefore FIP, in kittens
Kittens of FCoV antibody positive cats are protected by maternally derived antibody until it wanes, usually around 5-7 weeks of age, therefore it is possible to prevent infection of kittens by removing them from sources of infection.  Pregnant FCoV antibody positive queens should be isolated 1-3 weeks before kittening (3 weeks if they have concurrent feline herpesvirus infection). The queen and her kittens should be kept isolated from other cats in the house/cattery. At 5-7 weeks the kittens should be removed to a clean room (free of cats for over a week, well vacuumed and with a clean, disinfected litter tray). Kittens should be antibody tested when they are ten weeks of age or older and rehomed as soon as possible if seronegative. Antibody-positive kittens can be retested every 4-6 weeks until they are seronegative, then homed.
Vaccination of cats before first exposure to feline coronavirus
There are intrinsic challenges in creating a fully reliable vaccine for feline coronavirus (FCoV) when even natural infection does not convey lasting immunity. At time of writing, there is one intra-nasal FIP vaccine available. Felocell® FIP (formerly called Primucell® FIP) produced by Zoetis (formerly Pfizer Animal Health) is available since 1991 but not in all countries. It is a temperature sensitive mutant coronavirus which can only replicate in the cooler nares (and cannot replicate systematically). It is administered intra-nasally, the first doses being given at 16 weeks of age, or later and the second dose 3 weeks later.
The vaccine appears to be safe; however, many questions have been raised over its efficacy with different studies providing very different results. An independent study concluded that vaccination can protect cats with no or low FCoV antibody titers and that in some cats vaccine failure was probably due to pre-existing infection. 
Felocell® FIP will not prevent FIP in cats already viremic with FCoV. Nevertheless there are some situations in which the vaccine may be of value – if kittens have been reared under conditions to prevent exposure to FCoV, they could be vaccinated prior to introduction to a high-risk environment, and similarly if other seronegative (or low titer) cats are being introduced to a high-risk environment, these too may benefit from vaccination.
Vaccination against FCoV is generally not recommended by the American Association of Feline Practitioners (AAFP) Feline Vaccine Advisory Panel. More details can be found by reading the 2013 AAFP Feline Vaccination Advisory Panel Report published in the Journal of Feline Medicine and Surgery (2013), Volume 15, pp 785-808 available from www.sagepub.co.uk
DISCLAIMER: The use of this website is at your own risk. This website is for information purposes ONLY, and it is NOT meant to replace a consultation with a fully qualified veterinary surgeon (veterinarian). It is NOT intended to be used to diagnose or treat any cat. The creators share their personal experiences, recommendations of treatments, foods, medications, supplements, and products for informative and educational purposes exclusively. The information in this site cannot and should not be used as a basis for diagnosis or choice of treatment. Creators and contributors exclude all liability whatsoever for any loss or damage arising out of use of this site or reliance upon its contents. Furthermore, creators and contributors strongly advise all users to always seek the advice of a qualified veterinarian and to obtain professional advice on the correct regimen for your cat and his or her particular situation. NO responsibility can be accepted.