My friends horse had what vets thought was a stroke last year. He had just jumped at Hikkers and they reckon he was soo run down, exhausted and had also picked up a virus being stabled there. She rang me in pieces one morning as he looked like he had been poisoned or sedated? He used to whinney at everyone so we reckoned it was thieves shutting him up . Bloods revealed nothing, took him to Liphook where he was so tough and go, quiet, dozey, lethargic. Nothing like himself at all. They think it was a stroke/a horsey meningitis as his brain swelled. It was ages for him to be normal, I rung her to say he had neighed at me cuz it was that much of a breakthrough!
Shes competing him BE at the mo ..
Unilateral ataxia (incoordination), paralysis, loss of muscle tone, particularly obvious in the face and in the gait. I've see at least two older horses who seemed to have had strokes - although one vet told me it's impossible in horses I don't see how that could be. In each case there was no sign of trauma and only one side of the horse was afected. Both recovered somewhat, the one to the point of being safe to ride again.
I've seen similar signs from neck injuries. One horse pulled back in a halter and noticably damaged the nerves on one side of her face, one hit his neck and over a couple of days developed severe ataxia, although it was bilateral. Another horse had neck "stiffness" and gait changes.