Horses that “Cast” Themselves

Have you ever walked through the barn, or maybe you just put your horse away in a freshly bedded stall, and suddenly you hear mad thrashing and banging around from the stall? Then when you look in the stall you see your horse flat on his back against the stall wall with his feet up in the air banging and scraping the wall as he tries to right himself to get up but cannot. Your horse has tried to roll and is now “cast” meaning he is stuck and unable to roll back to the side he started from and get his legs underneath him.