Hi Terrie,
So sorry to hear that Dukee and Vinnie are struggling. FIP is scary, but it is so hard to diagnose that even if his FCoV titre comes back high, you can't know for sure that it has mutated into FIP. A blood panel which includes an albumin/globulin ratio can help to diagnose, but a necropsy when his time comes is the only sure way to know. And even if that came back positive, your remaining unrelated kitties only have a 5-10% chance of having the virus mutate into FIP. We lost one in August to suspected wet FIP (unfortunately no necropsy was performed), but none of her siblings have developed it, knock on wood. I am not sure what your vet means by "treat them all as if they have FIP". With 10 kitties, it is likely that the corona virus has been present in your house for a long time, just as it is in most shelters and breeding facilities. You can try to minimize stress on them, have good cleaning practices, and feed them the best diet you can afford to try to minimize the chance of it mutating, but not much else that I know of. Those are all things that are good for any cat anyway... (The only thing that I would do special is to avoid bringing any new cats in at this time, especially any young kittens.) It is pretty much a matter of odds, and please know that they are very much in your favor.
Prayers for you, Dukee and Vinnie,
Beth
