Bit of an odd case. I'm thinking allergies? I'm working with a three year old that tosses its head. It does it standing tied, when being ponied, when in the pasture, bareback in a halter or while being ridden with any bit. Gives to bit and halter pressure very well, not teeth, not saddle fit, doesn't appear out or sore any where. Its not violent, and in many cases just seems like a boredom thing, but its annoying. When being ridden I've started on rein stopping every time the head tossing begins, which stops it right away, but yesterday I was ponying the horse and it was head tossing every so often with no pressure whatsoever, then it wrapped the lead over its nose while standing tied and was tossing then, and was tossing a bit as it was trotting out to pasture.
so, a quirk? Allergies? Something else?