Was just going to post is it grass sickness or atypical myopathy. Then realised he had died so read through the last few posts! So sorry to hear your news & that there was nothing the vet could do. I have heard of 3 horses dying this way now ( different parts of the country) but all have been...
The RSPCA are not doing anything according to site on FB! They don't think the horses are in any danger? The water has risen again in the last 24hrs if it rises again they will all drown as there will be no where for them to go. Very sad situation :(