If instead of stepping forward the horse tries to back up, go with him. Continue tapping his hip or, if need be, ask him to do a hips over so that he doesn't back out of your control. Begin from where he stopped, asking him to approach the trailer again.
If he tries to push between you and the trailer and you can't easily prevent that from happening, step back to let him pass. Don't risk getting stepped on or having the horse hurt himself on the trailer.
Using the cues and timing you have taught him, you'll eventually end up at the trailer door again, with the horse's nose facing into the trailer. That's good. Pet him there and begin again.
Have the horse step one foot onto the trailer, leave it there, and step it off on cue at least 25 times. When he can do that in a relaxed way, leaving his foot on the trailer until you ask him to step off, then you're ready for the second front foot.
Ask him to step the first foot onto the trailer, and then ask him to go forward again. When he has two front feet on the trailer, pet him, allow him to stand, and then ask him to back off the trailer.
Do that at least 25 times. You may have to do it 200 times, varying the amount of time the horse stands in the trailer, until he'll wait for your signal to back off. You are teaching the horse to be patient in the trailer and to back off calmly, so don't rush through this step.
Three Feet On
When you feel that the horse is ready, ask him to step his two front feet into the trailer, then ask him to go forward again. Stop tapping the moment that a hind foot moves forward. It may take lots of little steps before the horse is ready to put a third foot in the trailer.
Control each step and do not allow the horse to step fully into the trailer. It's important to go through this three-feet-on step because this is the time that the horse learns how to step down as he's backing off.
Ask the horse to step forward until he raises one hind foot and rests it on the trailer floor. If he tries to back off, raise your whip and ask him to step forward again. Allow him to stand for just a moment and ask him to back. When he seems confident about this step, you can allow him to bring all four feet into the trailer. Don't let him rush forward to the front.
Stepping down is the scariest part for the horse because he doesn't know where the ground is. Allow him to take his time. He may try to step down and then step up again. Just pet him and guide him. Ask him to back off the trailer a moment before he tries it on his own. That way he'll learn to wait for your signal.
Finishing Touches
Now it's a matter of practice to get the horse comfortable getting in and out of the trailer, waiting patiently in there, and becoming familiar with all the trailer noises. Practice loading and unloading. Sometimes ask for one foot, sometimes for three or four. Mix it up so the horse learns to be confident with your signals.
Do not tie the horse in the trailer. Begin to move around, swinging the doors, opening the windows, dropping the butt bar against the wall, and so forth. If the horse comes rushing out, don't make a big deal about it. Instead, immediately ask him to step into the trailer again. Then raise the lead rope to ask him to come out before he tries it on his own.
After he's comfortable getting into the trailer, staying there, and coming out on cue, then it's time to think about closing him in. Prior to then, you should have made plenty of noise, rocked the trailer side to side, and opened and closed the doors frequently, though without fastening them closed.
Once the doors are closed, you can tie the horse's head, though only if he's been taught to give to pressure. As a little test, ask yourself if there's any chance he might pull back if he were tied outside of the trailer and got startled. If the answer is yes, don't tie him inside the trailer. If you do tie him, remember to untie him before you open the back doors.
When the horse has been in and out of the trailer about 200 times and is standing quietly inside the trailer with the doors closed, you're ready for his first ride. Fire up the truck and ease forward about 20 feet. Stop the truck and turn it off. You've just finished your first haul.
Assuming the horse is standing quietly, leave him alone for a minute or two before untying him and then opening the back doors. Pet him and tell him what a great future awaits down the road-and pat yourself on the back for a job well done.
