knightrider- I love that photo! You're gorgeous and looks amazing!!
Lots of dressage riders have been on since I've left
my how things change.
Presuming you've eliminated physical reasons. Do you know much about her history? I've known quite a few dressage horses to develop habits from their training life. I used to have to re-train dressage horses from other trainers and some were so mentally gone they had to change disciplines or came with funny habits. I had a mare who always had a running lip because the trainer she came from, though a GP rider always creates horses with strange mouth issues. Another horse I took lessons on came from her, I schooled PSG-I1 on that horse but he'd occasionally stick his tongue out of his mouth and we never had that totally solved but over time it got better. I've known a few with psychological and emotional damage and sometimes they're too far gone. Mares tend to hold onto those sort of wounds more than geldings. But I've also encountered a lot of dressage horses who might have shown a high level but they dont really understand their job. They've been made to do something and do movements but they don't really "understand." It's hard to explain.
And horses who are used to being pressured or have had knowledgeable but forceful riders can be more defensive. I rode a gelding who had been in training with an olympic dressage rider and he came back with all kinds of weird defenses. He and I got along really well, I never had a problem but he bucked off other riders and I heard would rear but I never saw or experienced it.I remember he always needed to feel like he was getting away with something. I always asked, I never told. I approached him as could you do this for me? I always had to accept "less" quality from him, in exchange for his willingness to comply. Couldnt make him do anything. I think other riders saw the talent and pushed him so much that he just wasnt willing to play that game anymore.
Ive also known horses who are emotionally sensitive and the wrong "ask" triggers it. I ride a mare who has never offered to go up on me but I've seen her go up on other riders because they didnt approach her right. I can put pressure on her but I do it in a way where she feels she has a voice. People dont talk about mental riding or how mental pressure impacts horses, some horses are emotionally sensitive respond very strongly to your mental approach with them and how you "phrase" the aids to them. When I ride I always start with my mental intent and emotion, then I position and then the aids.
I tried explaining once how to use energy to create or close off energy in the horse but I think that tends to be like trying to explain a color to a blind person. But the concept can help with emotionally sensitive horses. I rode a mare who if someone did not understand how to use their energy and mind to ride, she would just stand or back up until that mental connection was made, then she was lovely.
Though it could also be she's learned that rearing gets her her way, it's hard to say without seeing video or knowing her personally. But I do not think it's something that requires euthanasia. Have you done in hand work with her? How is she on the ground? Have you tried playing a game of where her line of discomfort is? At what point does she resist and to what kinds of questions? Like when I get on a new horse, I dont just jump in. I ask the horse "questions" How much to move laterally, how much to go forward, how much to rein back, how much to halt. I usually do turns on the forehand to feel the movement of the hind end and how much they understand crossing the inside hind to the outside rein.
I've worked with a few rearers, most I've been able to stop altogether but I had one who was a half arabian-warmblood and he was rearer. I was at his birth. He was broke by a cowboy. He scared me when he went up because he was mean, he could have killed me and not cared. He did it with everyone, Im not sure the reason or what happened to him. I thought I had it solved for a while and he was going pretty well, then I remember gathering the reins and he leaped up in the air twisting buck threw me into the wall and missed kicked my head in by a few cms. It was so close. My friend whose a very good cowboy type worked with him for a while and he never sorted through it either. Another trainer tried and no luck but he had a meanness in him.
I had another I developed who was a trakehner I rode as a 4 and 5yr old and he was sensitive but very straight forward and good. He went to a trainer who'd ridden PSG and fancies herself the only "correct" trainer but he came back from her rearing, bolting and super spooky. Im not sure what she did because when I was riding him, his amateur owner felt safe on him *Shrugs*
I had one the spinning solved the rearing. He used to go up on a loose rein because I closed my thighs and asked him to halt. When he learned to leg yield and if I didnt release in the right timing, he'd rear. The spinning fixed that with him and he stopped altogether.
My horse is a special case, he usually doesnt but sometimes he's like no way lady.
An example would be I was riding medium down a long side and asked to shoulder in, he dropped back and didnt want to push through his body. So I put both legs on and he went up. I laughed so hard because it was pretty funny, did a 10m circle and asked again and he was like oh right. Or another time we were doing an extended trot and I closed my hip angle and hand, held my core asking him to come back and he went up and bunny hopped forward
with him I've learned to just have a sense of humor and move on.
If you have video, you're free to PM me.