i have a question i am looking at a horse who has a problem of throwing or should i say nodding its head while tacked up only. She does not do it in the stall or outside and she is fine in the showmanship classes. she also does not nod her head when you put a piece of nylon knee high around the top of her snout not over her nostrils. she does not seem to nod her head in the cold weather either. does anyone have an idea?