My horse is a 25 OTTB that whenever I trot he shakes his head all around. Up and down, side to side, just all over the place. It is not his tack nothing is to tight or to loose. Ive tried giving him a long rein and a short rein and neither helps. He even does it while I a lunging him. He does it in the cross ties to sometimes. He will sometimes do it at the walk alot at the trot and sometimes a little at the canter.
Answer on How to get him to stop doing this?
Have you had his teeth checked? It could be that.
It could be an allergy issue as well. My horse has allergies, so certain times of the year he head tosses.
There are so many possible reasons for head tossing! It could even be his eyes, some horses have sensitive eyes so that when light hits them at a certain angle they head toss.
Of as the other person said it could be a behavioral problem.
My horse had a horrible head tossing problem when I got him, (he still does a little when his nose is all runny) but basically I got a ring martingale like this one http://www.horseloverz.com/TORY-LEATHER-… which gave me a lot more control over where his head was going. Also I started going in little circles every time he head tossed, until he stopped, and then back out on the rail. Head toss start again, little circles again, head stop, back on the rail.
For me that seemed to help.