I’m so sorry you’re going through this. I was in a similar situation last year-- new-ish to horse ownership with a dangerous horse. I had a thread about it here: Help with medical causes for bucking/bolting/anxiety . The vet hospital’s conclusion was EDM (a neurological disease that is not well understood.)
My gelding was dangerous under saddle and iffy on the ground, and went through multiple trainers. He exhibited the blind panic that others have mentioned. Like with your mare, there were circumstances where things were better and where they were worse. One of the trainers I sent him to-- the one who had the most hope for him, initially-- was always looking for positives. “Well, when we ride outside, as long as there’s no traffic and it’s not windy, he’s not too bad…”. But “not too bad” under very restricted conditions isn’t the same as “safe”.
When I posted here, I had a mix of suggestions for medical investigation and recommendations to euthanize. Like you, I didn’t want to make a euthanasia decision based on what a bunch of “internet strangers” were saying, even if there were a lot of them saying it, but reading over the responses helped me approach the conversation with my instructor and vets.
Ultimately, these were the questions I asked:
(1) Does there exist a person who could safely handle this horse, and is that hypothetical person likely to want this horse? Even if there is someone with the skillset and barn setup for this kind of horse, they probably don’t want to put up with this behavior unless she’s spectacularly talented in some way.
(2) If you send her to a retirement barn or rescue, can you trust that the people there will be safe around him? Given that the experienced barn staff at my barn were nervous around my guy, I thought that the answer was no. There are a lot of inexperienced people out there who think that they will be the ones to fix a horse, and I didn’t want it on my conscience if he hurt someone.
(3) I outright asked my vet whether they would support me in euthanasia. She hadn’t brought it up before, and neither had my instructor or the trainers I had sent him to; but when I asked about it, it turned out that they were supportive. Some people, I think, are reluctant to bring up the idea of euthanasia for behavioral reasons.
Even after all that, I needed the complete vet workup (orthopedic, ophthalmologic, and neurologic) before I could make the decision. He displayed no instability or gait irregularities or other signs or a neurologic disorder, but ultimately, that’s what the vet hospital’s conclusion was. (He had a bad episode while there, which helped.) I don’t think that I could have been at peace with the decision without the complete vet exam.
This next bit is probably not helpful, but I’m including it just in case it is. In processing my emotions about this, both during and after the decision, I was angry and sad about the entire situation. I still am. It wasn’t just the grief of losing my friend, but it was the sense that all of this had been a waste: a waste of my health and a waste of his life. Normally in a bad situation, I can find some silver lining, but here there was nothing. I mourn for him every day-- he injured me, and I’m still recovering; but it was the one single life he had, and now it’s gone, and for what? No matter how I tried, I couldn’t find any meaning in it.
Then, after many months, I realized that maybe he didn’t come into my life for my sake, but I came into his life so that I could help him. I could have sold him, and I think that a lot of people would have. But I’m certain that I made the right decision for him. That was the gift I could give him. It wasn’t how I had imagined our time together, but it was what he needed.
Good luck.
