You punish in the middle of an act so the message is that the act is bad but stopping is good. The horse was tugged on the mouth and tried to escape, she should have smacked it yes but not once it had come down and not on the head especially not with a crop. Because you have seen worse does not make this right and I feel quite sad that you think we are over reacting. I've been on a rearer but I didn't smack it on the head once it had come down. The way I see it the only acceptable time to smack a horse on the head is if it is biting you and then you do it as the horse is either going for you or has hold of you.