Looks like you're right about that.... I found it banned in other disciplines.
It would be hard to establish parameters that are fair, for when it was OK to use a drug and when it's not. But the objective of NATRC (so they say:) is promoting good trail horses and good trail horsemanship. Well, if you have a good trail horse, but he has some problem that has to be treated to keep him a good trail horse, I find it hard to accept the ridgity of their rules. If a horse is on a drug per a vets reccommedation, and the rider has documentation of this, I think it should be acceptabe.
NATRC, has a rule that has always bothered me. They don't allow any type of leg protection. No type of boot, but then they will and do mark off if in going thru rocks a rock puts a nick on your horses leg. The reasoning is, the horse was not paying attention to where he was putting his foot. But, hell we go thru rocky creeks....how can they see rocks underwater.
IMO, good horsemanship is putting something on your horses legs to protect them from such things.
But I've learned, there are going to be rules in any organization you don't like, you just have to deal with it. If you know the rule going in, then don't complain, is what I tell myself:)
Becky