Thanks all.
Doddsy I gave the vet all the poison info as you suggested. Thanks for the suggestion.
AndyL I do not think is is Distemper, no rash, no discharge and his shit is normal, but will definately keep an eye on the others in case they exhibit any of those symptoms! Sorry about your stinker, nine is a respectable age. This fellow is only three so I am quite upset that his rabbiting career may be cut short!
Took him off to the vet this morning who agreed it does look like a case of poisoning, he was worse than last night so they're keeping him in for fluid therapy, anti-inf