Making an 8 mile haul with no manger and no hay net, with horse tied with a velcro breakaway trailer tie. I felt the trailer shake and could not see a head on the trailer monitoring camera. My 17hh draft had pulled free of the velcro safety release tie and had wedged his head and neck under the chest bar.
If there is a way to get in trouble, a horse will find it, even in an empty trailer.