Always try to get someone to help you with loading a problem horse into a trailer. There is a very real safety risk involved in getting a horse into a trailer when he is not in the mood to do so. The horse is most likely to resist what you want him to do and hurt you in the process. Having a helper involved in the process of loading the horse into the trailer will allow you to complete the task much easily and reduce the risk of getting hurt.
Get your horse to relax and ease his tension by leading him around for about 30 minutes. An anxious horse will not let you lead him into the trailer, which is why you need to remove his anxiety and remind him that it is you who are in control, not him.
Once you have eased the horse’s tension, take him to the rear of the trailer and allow him to take his time to inspect and smell the trailer. You cannot expect the horse to step into the trailer until he is comfortable with it. Forcing the horse to do something against his will would only lead to him becoming a bigger problem than he already is.
Holding the lead line in your hand, enter the trailer yourself first and then start pulling the horse towards you. Be sure to pull the line slowly and gently. Give the horse a few seconds to register what you are asking him to do. Do not become impatient if the horse resists the pull at first. Give him time to relax. Talk to the horse in a soft voice, comforting and petting him. If he starts to enter the trailer and then steps out again, allow him to do this. He is likely to step inside the trailer completely eventually.
Your helper can help you with the loading by holding one end of a rope at the horse’s rear, while you grab the other end. Step inside the trailer and start pulling the lead line and the other hope that you are holding at the same time. Remember to be gentle as you do this.