Join Date: Jul 2010
Location: East Central Illinois
The best and safest way to retrain him is to train him to not fear a human sized door. Do you have any at your barn? I used to lead my horses randomly into the building that I kept my hay and extra tack when I was teaching lessons. It was the typical 34" wide and 6 ft tall human door and the building was dark even with the lights on.
You could start by using a long lead rope, walking though and waiting then ask your horse to walk through it from the inside to the outside, at first, and then, the other way.
I own a 4-horse slant load and the entrance is narrow.
Using a regular door, your horse isn't gonna feel trapped bc they is an exit. He will show some fear. Just keep repeating every day until it's no big deal. Then, the trailer should also be no big deal, too. =D