Dr. Addie - How to prevent FCoV transmission

See also What's new in FCoV/FIP research for the latest information on how long cats shed FCoV, and the use of the virus detecting tests called RT-PCR.

FCoV is a very contagious virus, infecting nearly all cats who encounter it. The major source of infection is the faeces of infected cats, and uninfected cats become infected by sharing litter trays with infected cats. The second major route of infection is the unintentional exposure of uninfected cats to tiny particles of infected faeces on people’s shoes or clothing, hands, poop scoops, etc. The infected cat likely swallows the virus when grooming, or when particles of faeces contaminate their food.

FCoV is occasionally shed in the saliva, early in infection, so sharing food bowls or inhaling sneezed droplets could possibly allow infection to occur. Close contact with infected cats, for example in mutual grooming, might, rarely, result in infection.

Feline coronavirus almost never crosses the placenta to the unborn kitten. Most kittens which become infected do so after protective antibody they receive in their mother’s milk has waned, usually when they are 5-7 weeks old.

FCoV is mainly shed in the faeces, and is only shed in the saliva very rarely. At present, there is no evidence that FCoV is present in the tears or urine.

If your cat uses a litter tray, then make sure it is declumped as often as possible and use dedicated poop scoops for each cat pen or tray. Better still, if possible, let the cat out to go to the toilet naturally outside (I am aware that this is not always possible or desirable where there is a lot of traffic). If you have several cats, make sure that you have enough litter trays, preferably one for each cat, and get covered or even self-cleaning litter trays. Site the litter tray away from food areas so that microscopic faecal particles cannot be blown onto the cat's food. Use a non-tracking cat litter, to minimise spread of microscopic particles around the house. Once or twice a week, clean your litter tray with domestic bleach (sodium hypochlorite). Do stick to bleach disinfectants, as pine based ones are toxic to cats. Vacuum as often as possible to reduce the number of contaminated cat litter particles.

We have been assessing the activity of various cat litters against feline coronavirus in the laboratory and are pleased to announce our results. Please bear in mind that cat litter can't wholly prevent virus spreading from one cat to another by microscopic particles on shoes, poop scoops, etc. The virus will, to some extent, be protected by faecal material. We have not yet assessed how litters which track less affect viral transmission.

CAT LITTER	LITTER TYPE	Anti-virus Rating

Ever Clean® Less Track	Fuller’s Earth	*****
LitterPurrfect (San Diego, imported by Costco UK)	Fuller’s Earth	*****
Tesco Value	Fuller’s Earth	*****
Cat Country USA	Compressed wheat grass	*****
Sophisticat	Fuller’s Earth	****
Pets at Home	Wood pellets	***
Catsan	Softwood granules	**
Snowflake	Wood pellets	**
Litter Pearls (Crystal Clear Pet Products)	Silica gel	*
Nutrina Nature	Chicken feed	*
Tesco Premium		*
Cat Country UK	Compressed wheat grass	*
Cat Country Europe	Compressed wheat grass	*

Key:
***** killed all the FCoV
**** killed quite a lot of FCoV
*** and ** killed some FCoV
* didn’t kill any FCoV

In natural circumstances, cats go outside to defaecate and bury their faeces, in which case the virus lasts hours to days (it survives slightly longer in freezing conditions). However, in domesticating the cat we have introduced litter trays: FCoV may survive for several days and possibly up to 7 weeks in dried up faeces in cat litter.

If you have lost a cat to FIP, wait around a month before obtaining another cat. However, if you have other cats already, remember they may be shedding FCoV, so wait until their antibody titres have reduced to zero before obtaining a new cat. Of course, don’t forget to test the new cat for FCoV antibodies too.

FCoV infection can be eliminated from a cattery, but it is a long and sometimes expensive process. Households of less than 10 cats will often spontaneously and naturally become FCoV free, but in households of more than 10 cats, it can keep passing from one cat to another (see fig 1.) and maintaining the infection in this way.

Table 1 shows an example of a household of cats who lived with Carol, Ann and Simon Hicks, who successfully eliminated FCoV infection. Cats were tested for antibodies and their faeces were tested by RT-PCR regularly. Cats who had stopped shedding FCoV and whose antibody titres were declining to below 40 were separated from the other cats. Fortunately, Carol was leaving home and was able to take 4 negative cats with her to her new home, but other cat lovers have successfully managed to keep infected and uninfected cats apart within one house). By August 1997, 17 months after the FCoV infection had been detected, only Sooty was still infected. Ann moved Sooty to the bedroom in complete isolation from the other cats. By January 1998, it was becoming clear that Sooty was a FCoV carrier and since she was miserable isolated in her bedroom, it seemed likely she would have to be euthanased. Fortunately, the Hicks agreed to give her to me (my own two cats had died a few months previously and I had no cats). Sooty still lives with me, seven years on, and is now FCoV free. She was a healthy FCoV carrier for many years.

Table 1. A household of cats from which FCoV was successfully eradicated by isolating cats which had eliminated FCoV infection from those who were still shedding virus. The shaded boxes indicate when a cat was moved to another household.

The numbers are the cat’s antibody titre.
+ = positive RT-PCR result of faeces or rectal swabs
- = negative RT-PCR result of faeces or rectal swabs
N/D = not done

At present, identifying carrier cats is a lengthy process (see What's new in FCoV/FIP research). We still need to find some test which will identify lifelong carriers sooner so that we can keep them apart from other cats, or to find a way to stop them shedding FCoV..... but these are the subjects of my future research.

Once your cats are FCoV free, take care not to re-introduce the virus. Test all new cats or kittens for FCoV antibodies using a reliable antibody test, such as the immunofluorescent antibody test from the University of Glasgow (see link to Companion Animal Diagnostics). There appear to be many antibody tests available which have no correlation with the Glasgow University gold standard test and using them will not only give you worthless results, but may endanger your cats’ lives. Only cats with an antibody titre of zero should be allowed to come into a FCoV-free cattery.

Make sure that you only take your queen to stud cats with antibody titre zero and that only antibody titre zero queens visit your stud cat (see the Coronavirus tested stud and queen register). When you go on holiday, for preference, get somebody to come to your home and feed your cats rather than putting them in a cattery.

Quarantining your cat after risky sex, a visit to the cattery or cat show, or stay at the vets. If you decide to mate your negative cat to a cat with FCoV antibodies, or your cat has been at a show, cattery or had to stay in your vet’s kennels, then place your cat in quarantine at home for 2 weeks and test him or her for FCoV antibodies, making sure (s)he is negative again before re-introducing him or her to your other cats.

Can I visit my friend, whose cats have FCoV?
It is extremely unlikely that you could bring the virus home to your cats on your person, unless you actually had infected cat faeces on you.

I’ve heard about canine coronavirus – can my dog infect my cats?
The short answer to this question is probably no. Type II feline coronavirus is actually a mixture of the type I, or wholly feline, coronavirus, and canine coronavirus (CCV). Therefore it is likely that CCVs can infect cats, since it must have been present in a cat with FCoV for the type II strains to arise. However, CCV doesn’t harm cats and in my research we tested any dogs within survey households and only once found a dog with antibodies to coronavirus.

In the UK, 84% of cats are shows have antibodies to FCoV. Since, on average, one in three cats with antibodies to FCoV sheds virus, it would be likely that 28% of cats at shows is shedding FCoV at any one time. FCoV is mainly shed in the faeces, so cats at shows should not share a litter tray or poop scoop with cats from other households. Judges and veterinary surgeons should disinfect their hands and the table between handling of each cat: remember that some cats in early infection shed FCoV briefly in their saliva.

Obviously it is wisest to mate only cats with an antibody titre of zero to other FCoV free cats and cats with antibodies to other cats with antibodies, hence the FCoV tested stud register to help breeders to find each other. However, sometimes cat breeders have reasons for wanting to do a risky mating (of their cats!!!). In this circumstance, it is best to do a controlled mating, that is where the queen and tom do not get to live together for a day or two (so, importantly for FCoV transmission, do NOT share a litter tray) but are only put together for the duration of the actual mating. Clearly, the cat who was previously negative should be tested for antibodies 14 days after the mating to find out whether he or she became infected in spite of the precautions.