I have a 10 year old Quarter Horse mare. She is AMAZING on the ground and while riding around barrels. But, when I just want to pleasure ride her, or go on a trail ride she gets aggressive. Her biggest issue is loping. When I ask her to lope she pins her ears, shakes her head, swishes her tail, and she will occasionally buck. I have not loped her around the barrels yet, I just started working with her around them. Sometimes she does this when I ask her to just trot or turn. Is there any way to put a stop to this? She is just a completely different horse when under saddle. Thank you!