usually as I understand it here from my horse friends, the typical horse training is to remove the stimulous from the animal as soon as the desired result is achieved (i.e. pressure on the reins until the head falls into position). The people I've talked aren't really confident in clicker training and horses(yes, I know I've seen clicker trained horse videos), since the typical training involves body language and respect.
I think what you hear of/think of as far as breaking a horse is actually fairly uncommon - my friend just broke hers and said she was able get in the saddle on the first try and even ride her a little - no problem. Apparently some horses are just like that, I think more often then not, actually.
I do know that as far as working on problem behaviors the same principle applies, so that "never give up" and "end on a good note" are also utilized.
I think another thing to remember is that horses are so large - if a person gets physical with them, it isn't the same as if someone were to hit a dog. My other friend works with young horses getting them ready (socializing them with handling and "scary" things) for showing and riding and eventually they'll be raced; she had an incident the other day with a young colt just over 1 year old(just starting to have his testicles drop and feel his hormones), he pinned her against the fence and then kicked her out of the blue, there was no other way to get him to stop and gain some respect but to get physical with him. I think it's kind of like the prong collar - it looks worse then it is. When you think about it, there isn't much that a person could do on their own to a horse that wouldn't rival what another horse would do.

I can only please one person per day. Today is not your day, tomorrow doesn't look good either.
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"You didn't know of the magical powers of the break stick? It's up there with genies and Harry Potter as far as magic levels go." SisMorphine 01/07/07