Start practicing weeks before you must transport your horse.,
Associate the trailer with good things and keep it as un-scary as possible.,
Get the trailer rolling.,
Practice long drives.,
Don’t act any different on days you are going somewhere.
Lead your horse over to the trailer and let him sniff around it. When he’s comfortable sniffing the outside, put him back in his paddock. The next day, open the ramp and let him sniff the trailer again. Allow him to sniff the inside. The next day, show the horse some grain inside the trailer. If the horse steps inside, give him the grain, pat him, and lead him back out. If he doesn’t, keep showing him the grain until he steps even just a little bit onto the ramp. Keep working over the next week(s) with grain or hay or a carrot as a reward until your horse is comfortable just standing inside the trailer.
Remember that although treats can be a motivator for horses, horses are prey animals and won’t care about food while extremely nervous. It may take you relaxing in the trailer and being a confident leader while asking the horse to load for the horse to do it.
Make sure that you practice with loading on a sunny, cool day with no distractions. Make sure there are no dogs barking, or other horses neighing.
If you can, roll the trailer out into an empty field and practice there.
, Open all the windows and vents, perhaps relax in it yourself for a while (in clear view of your horse), then ask your horse to load.
, Once your horse is comfortable standing in the trailer with the ramp open and closed, hitch up the trailer and take it for a short drive around the field. Just drive around the perimeter once or twice-depending on the size of the field- to get the horse used to the movement of the trailer. Once he’s comfortable with the movement, take him out on the road for a couple of minutes.
, Every once and a while-maybe once a week-take your horse for a longish drive in the trailer. Maybe you can go grab some lunch at that place that’s hard to get to. (Make sure you let the horse out to stretch his legs a couple of times.) Then take him straight home. That way, he won’t always associate the trailer with work.
, Have things loaded beforehand and don’t get stressed or rushed. If you do, your horse will know something is going on and will get jittery. If you’re ready ahead of time, he’ll probably think this is just one of your joyrides and that he doesn’t have to work much.