I had the vet out today, and the short story is that I still don’t have a firm answer and what I have is not excellent news.
First we lunged Simon in the round pen, and he looked sound both directions. Didn’t show any of the dropping behavior I described to her at the walk, trot or canter.
Next they flexed his hock/stifle/suspensory. He jogged out pretty well with the left, and slightly worse to the right but still not awful. She palpated his suspensory, which he was sensitive. Since nothing huge was showing up, I tacked up so I could show her the behavior under saddle.
One lap at the trot to the right and she immediately saw what I was feeling. I felt extremely validated that I wasn’t a crazy person making up problems for my horse. I trotted to the left, and then trot/cantered to the right again. When I was done, we discussed next steps.
Overall, the current diagnosis is upper hind suspensory. Most likely on the right, but potentially on both hind legs. We want to ultrasound obviously, but they didn’t have a portable machine so he will have to go to the clinic on Friday afternoon for that. She said it was a big red flag to her that he improved pretty drastically after his hock injections (though short term), because when you inject the hock the suspensory also gets some of that “good juice.”
Also, he is very sore in an area of his back. It’s behind the saddle, and almost looks a bit like a hunter’s bump. She was concerned about kissing spines, and wants to take some views of his back as well on Friday.
Right now I’m trying to keep myself together, but I am very worried. I’m quite aware that a suspensory, especially an upper one, can be a career ending injury. I can patiently wait through time off, but I don’t want him to be done. Not yet.