Our new mare is super handy. I can do anything around the farm with her with ease, and she is super calm. I can take her on the trail alone just fine and she is calm and attentive. Due to a little too much sugar (I'm guessing, as the grass here is MUCH more lush than the grass she was on at her old farm. We bought her two weeks ago), she has been a little spazzy a few times on the trail, but always listened and never bolted or tried to rush.
However, bring another horse onto the trail and apparently she loses her mind. We began in the middle of 3 horses with no problem. Calm, loose rein, same ol' same ol'. We came to a hill and the horse ahead of us trotted on up it. She is barefoot and the hill is gravel, so I wanted her to take it easy so as not to hurt her hooves. The moment I began sitting back she started to go faster, so I took up light contact (she's in a basic curb) and told her "easy".. nope. The farther away the other horse got, the more she tried to get up the hill faster. Eventually she broke into a canter that was actually at a trotting speed. I pulled her off to the side in a flat grassy spot once we got there, and the other horse was by now out of sight. This is when she lost it. She began to suck back, toss her head, and eventually paw the ground violently when I would not let her go forward. All this time I had VERY light rein contact, but enough for her to know that I was not allowing her to go forward. When she began to hop on her front feet and slam her foot into the gravel, I spun her around (which she did frantically, trying to get back to facing the other horse), and I decided to tell her to walk on. She jigged super excitedly the rest of the way up the hill, and only calmed down and walked/stopped once we reached the other horse.
I wanted to make sure this wasn't a fixation with that particular horse, so I did several tests the rest of the ride, and she did the same thing, acting as if she was going to flip over backwards, any time the other two would get even too far ahead of her for her own liking (not just out of sight or moving faster than a walk). If the other horses passed her and I held her back, she started again. When going in front of the pack, she was fine.
I have another trainer coming Monday to help me work her through this. We plan to have other horses pass her repeatedly while we work on her standing still/not breaking gait/not sucking backwards and upwards. I imagine we will practice this holding her on the ground as well as mounted.
What do you think is the issue here, and how would you go about fixing it? I am not scared of her by any means, though I am 7 months pregnant and can't afford a horse flipping over backwards on me, hence the other trainer coming to help.
Sorry for the long-winded post. :) Thanks in advance!