I have a 7 yr old mustang mare that gets VERY excited on rides outside of the corral whenever she sees another horse in the distance or heaven forbid close. She raises her head, snorts, holds her tail straight up and goes completely out of control. This happens whether or not I am leading her or riding her. I have tried the "calm-down" cue to get her to lower her head but she pays no attention. When I turn her in tight circles she gets even more excited and starts rearing, head tossing, backing up, and bucking. I have also tried correcting quick snaps with the lead rope or reins. Nothing seems to break her intense concentration on wanting to go to that other horse and it's all I can do to get her back home. I have heard she needs exposure training, but what does this entail and how do I get her under control? Thank you!