I have a two horse straight load. I tie not only so they don't turn around in the trailer but also for my own safety when unloadin the horses. Kitty has been taught to load/unload herself by voice command so it's quite convenient. She will not move until you tell her to. However, Jesse is quite nervous in the trailer and will try and back out as soon as possible once the back doors open. Since he's so big, I took out the divider so he could have a little more space while traveling (he's the only one in there). The thing is, when I do that I can't put the butt rope up behind him so if he wasn't tied, he could just run out when the door's opened.
"You know, for as long as I can remember, I've had memories." ~Colin Mochrie