Vets phoned and he has survived op.
He had a blood clot (infarction?) in his guts and they've managed to rub the intestines and get it cleaned but its caused some damage and his glands in his tum are up and there is also fluid around his liver (so the FIP word of course mentioned along with some other big vet words).
Fluids to be given for the moment and see how he does. No samples taken as too small but then as vet says it doesn't make much difference to how he and his litter mates are treated.
Vibes he survives the night,