Hi, I am writing this letter to you from Natal, South Africa. We've got a horse that has a new problem, which just suddenly occurred. He never had traveling problems, and has been to quite a few shows. Now, when he travels, he starts crawling up the side of the box, so badly that he was lying down and got stuck under the chain. Nothing happened to him while traveling, so we really don't know where this problem is coming from or how to deal with it. When he goes into a 3-birth box, without partitions, it seems to be a bit better, but otherwise it is quite a disaster. One of the other horses is walking while traveling. Can you help with these two problems?
Your problem sounds like a tough one. For whatever reason, it sounds like your horse has become claustrophobic (afraid of confined spaces). This is a perfectly normal reaction for a horse, whose survival is dependent upon the ability to flee. When we take away a horse's flight response, he becomes afraid of things that would not normally frighten him. I would start over with him as if he were an untrained horse. Starting with a larger box, allow him to go in as far as he is comfortable and eat some tasty food. You can even feed him twice a day in there, but make sure the box is hooked to a vehicle for security. Gradually put the food in further and further until he is eating his entire meal inside. While it would seem logical to leave windows and doors open to make him feel like there is more space, do not do it. Panicked horses will frequently try to escape through windows and doors, no matter how small. Once he is eating in the trailer, then start shutting the back door and let him eat for a week or so totally confined in the trailer. Then you can start taking small trips.
By then he should be fine. It takes a long time to overcome a bad experience with a horse, generally longer than it took for the undesirable behavior to appear. It is worth taking your time. If you want to expedite the procedure, do several sessions a day, with breaks in between and feed all of his rations in the trailer. Physiologically, horses cannot eat when they are frightened. They must relax in order to eat. It is one way to discern whether a horse is being obstinate for trailer loading or is truly frightened. If he is eating and refusing, he is just being stubborn. The frightened horse will not eat. If that is the case, you will just have to find where his comfort level is, put the food there and gradually move the food into the box. Using forceful tactics on a frightened horse never works; it just makes them more afraid. If the horse eats, but refuses to get in the box, that horse needs some training to learn that he must go where you ask him to go. Start on the ground, away from the box and teach him to move as you ask him. This is a whole other subject and it doesn't sound like your horse needs this right now. Good luck and let me know how it works out.