Join Date: May 2009
Location: Winnipeg, Manitoba, Canada
At first thought, I'd say it sounds like he was tying up. Horses that are tying up becoming extremely stiff, reluctant to move, stumble frequently, and can fall down if pushed due to inability to properly use the "paralyzed" muscles. This is a condition that can happen with out of shape horses worked to hard, or horses being fed to much grain. It is also part of a condition called PSSM which actually runs in stock breeds and will happen regardless of workout or grain.
Was he sweating profusely? That is another major symptom. I would call a vet but I don't think you need to rush one out unless he's still staggering around drunk. Typically in cases like this, there's not a lot the vet can do unless it starts happening constantly.
More details would be nice, I could be way off base, it just sounded very familer to how my Paint filly was acting when she tied up.
I hope God tells her to smash her computer with a sledgehammer.