Originally Posted by Allison Finch
Actually, all you have to do is make sure your trailer is fully braced/blocked so that the back of the trailer doesn't sink down with the horse's weight in it. I have blocks that fit securely under the rear of the trainer and I have all four wheels chocked.
While I usually do my trailer training in a gooseneck, I sometimes have to train in a clients personal trailer when they are not there to hitch up.
Plus, it depends on the trailer anyway. Your small trailer would be the type that could possibly have the front end come off the ground with the weight of the horse in the back of it. It's not going to "flip over" but it sure could scare your horse (and you!). Make sure your wheels are blocked up so the trailer can't roll and make sure the underside of the trailer (in the back) is blocked so it can't sink down when the horse steps on it.
However if you had a larger heavier trailer, like a 4-horse gooseneck, that trailer isn't going to budge when you load a horse in the back. However, still definitely block the wheels so it can't roll. I've practiced loading lots of big horses into the back of large trailer and I've never had one budge. It's the smaller lighter trailers you have to be careful with.