We bought a lovely pony for DD in August and he has been a real peach. But when DD rode him today he was tossing his head and snatching the reins out of her hands. I put some side reins on him (well, baler twine) as a temporary measure, but he kept on tugging at the reins for pretty much the whole 30 minutes we were out which was unpleasant for DD.
Any suggestions on what is going on?