Just as a note, smacking the horse between the eyes isn't likely to work to stun it. The brain is up higher, just below the ears. (If you draw an "x" between the ears and the opposite eyes, the brain's centered in the middle.)
Had an obnoxious gelding who bit a chunk out of my mare's nether regions. When he came back for seconds, she kicked him so hard in the head that she put a dent in his skull between the eyes. He will have a dent (it is at least an inch deep) there for the rest of his life.
Gave him a bloody nose and I assume quite a headache, but he was fine, except for the dent.
If she'd gotten him about two inches higher he probably would have been dead.
Didn't stop him from being a butt, either.
-- Leva