I was recently at my first show with my horse, and for the first few hours she was fine, but all of a sudden she would rear and freak out. She would stop as soon as I pulled the lead rope loose. She did it a total of four times and I decided to just hold the lead rope and not tie her up at all. Every time she did it I got really scared that she was gonna get hurt. If anyone has any ideas on how to prevent her from doing this, that would be great. Thanks