I've ridden a couple Arabians (all of them just a little....shall we be nice and say "off"? Lol good thing I love the breed), and they all do this head-toss thing where they pull on the reins. None of them have issues with their teeth, so that's not it. I know not all Arabs do this, but I'm wondering if it's just theses particular horses, or if it's a common behavior in Arabs. Or it could just be me as a rider! But I've only noticed it in the Arabs.