Join Date: Feb 2010
Location: Western Australia
My heart horse used to have issues with sleep deprivation. If his paddock situation was not letter perfect he simply would not lay down for REM sleep. While horses can lock their joints and nap while standing up, to get the most important REM sleep they MUST lay down.
I discovered it after a similar occurrence to yours. We had introduced a couple of new horses in to the paddock Rex was in a few days before the incident. I was standing next to him, giving him a wither scratch. Next second he had collapsed beside me. Hitting the ground brought him out of it, but he was clearly shaken up. I freaked out, thinking maybe he had a seizure or something sinister like that. I had the vet out to do a full work up and draw blood. The blood work showed something called "leucopenia" which is often the result of exhaustion.
After that we made sure that he was only turned out with horses that were lower than him in the pecking order or on his own. On the odd occasion that for whatever reason he had to spend a few days in a "less than ideal" turnout situation he would begin to buckle at the knees whenever he napped and we knew it was time to get him back where he felt most comfortable.
Trojan 09.11.02 - 26.10.10 // Kody 01.09.89-25.06.12 // Rex 05.11.95-21.12.12