Our old, now gelding, used
to rear when you tried to worm him. Well he went up and hit his head on
the run in, awful sound! Any ways, he has never reared to
avoid the wormer since that, no matter where we are.
I've been reading about hitting the horse over the head
versus not hitting him if he rears. I had a horse that would rear, but not
often. Usually when something startled him or he just was having a bad day.
One day I was riding him on a narrow tree lined trail when a deer popped out
of the bushes. He reared and hit his head on a tree branch. At the same time,
my helmet hit the branches and made a terrible sound. He never ever reared
again after that. So I guess a boink on the head really does
work.