Chronically weak/sore back
So, about the beginning of September, Zeus started acting funny about his back. When mounting, his hind end would almost collapse- squatting down almost like his back couldn't take weight on it. Then he would bring himself up, take a few steps, and be fine. It didn't happen every time. He would stomp his back feet at a walk, his hind left especially. Riding bareback, he would hollow out his back as far as he could. He dropped a ton of weight for no reason. I was stretching him out every day, and he did get a painful muscle spasm once while doing his back legs (not sure if that's related).
I stopped riding and called a chiropractor. She came out and adjusted him, saying that the left side of his hip was a little higher, and that he had a rib out. Fixed him right up and said we could start riding again in 2-3 days. At this point I was riding for 10 minutes once a week, in the lightest saddle I could find (trail Abetta). He kept up the squatting maybe once every 6 or so rides, and the stomping.
So, then I thought it was his hocks, maybe arthritis. I made an appointment to check it out. Vet said no, it was in his back. He did acupuncture and adjusted him again, then bute. Took him home and gave him a few days to rest. At this point I believe the collapsing was almost nonexistent. (Side note- whenever he did this, I would walk him forward a few steps and get right back off, so he didn't learn "if I do this, she'll get right back off", but I did NOT want to strain his back any further.) He was still off, so I decided to give him the winter off, rode maybe 2 times in 4 months. I started him on DMG and he did absolutely wonderful. He was getting down and back up a LOT more easily.
I really thought that the winter off would get rid of his soreness. But now that I'm bringing him back into work, it's pretty much the same. Still hollows his back while bareback. Still stomps his hinds at a walk. Does not collapse his legs. I took him off the DMG in March and it's a huge difference. I can definitely tell he's less comfortable while ridden. Just put him back on it yesterday. We're working hills and long and low on the lunge to build up his muscle.
The farrier was also out yesterday, and he would NOT stand when she had his back legs up. He has always stood 100% quiet every single time. He leans back and hops over, not just regular "I'm going to pull my leg away from you". And today, I was brushing him and he flinches, tenses, and moves away when I'm brushing over his back. He even tried to push me away! That has never happened, he's very respectful of my space.
I don't want to slap a bandaid on the problem, I want to know what would make him sore for this long and treat it. The vet is coming out to do vaccinations by the end of next week, I'm definitely bringing it up to him. I was thinking maybe magnesium deficiency, or I was reading Cinny'sWhinny's post about Cinny's Lyme disease and drew a lot of parallels between them. I just wondered if any of you had any ideas about it. Thank you so much!