This is my first post here on horse forums and I apologize in advance it is quite long.
A QUICK BACKGROUND:
We picked up a young horse late 2018. A lady I have known for some time was a breeder going out of business and she could no longer take care of the horses. She needed to essentially "get rid" of some horses. It was not a good situation.
The horse in question was well-bred but unstarted and only 3 1/2. He was living in a field but we both loved him from the minute we saw him. We knew it was a big risk but figured at the very least he'd have a good home, we'd get him a good start and we could see from there.
A couple of months before we took him from the breeder he was moved to an all-weather paddock with a different horse who after a week of being out together beat him up VERY badly. The biggest hit looked like it was to his hock. After a week or so we did an x-ray to make sure everything was ok and luckily everything looked fine. The vet cleared him to start his training a couple of months later.
He came back to us after being started and we gave him about 4+ months off to grow. He is a big boy! At about the start of his 4-year-old season, he did some light walking and trotting with us but seemed to have this "hitch" in his RH. He'd start off a bit short in the trot but work out of it. But then coming down to a walk would take 3 very short steps and then be fine. We had vets and a trainer look him over. Both thought it was likely some weakness in his stifle and he needed lots of hill work and correct training to strengthen his stifles. We decided to send him to a lovely trainer who would do it right. Getting him hacking out and work on strengthening while not doing too much while he's still growing.
To end it here, after almost a year of many vet visits and bills, x-rays of his hocks and neck, a fluoroscope of his entire hind end, ultrasounds, bute trials, and eventually nerve blocking. Even a treatment earlier on for EMP (which did improve coordination and energy), the vet concluded that he likely has a soft tissue injury to his RH stifle (cruciate ligaments, etc). All other structures (joint capsule, meniscus and collateral ligaments) are showing up fine. It seems if he doesn't move around the lameness worsens (we trialed by keeping him in for a couple days during bad weather vs. when he has turnout for most the day).
Looking back with a critical eye at his starting videos he did look slightly shorter on is RH in the trot. As he's continued to grow it's become more pronounced.
It's been a tiring roller-coaster and this news has come as quite a blow to us. The vet thinks at most he will be a pleasure horse and is not hopeful that injecting will do any help. We don't want to give him away in fear he will get passed around or pushed into an athletic career by masking his lameness.
Has anyone had any issues similar to this? What did you do with your horse? Is there anything else we can do? Do we try to give him a year off and see if anything change or is it time for the retirement barn? We want to do the best by him and give him as best a life as possible moving forward.
Thank-You to anyone who made it through this long post. If you need clarification on anything ask away :) Any advice is greatly welcomed!
TL;DR - Young horse we picked up out of a field is now showing strong signs of RH soft tissue damage. We don't know what to do as far as a way forward. Any advice is greatly appreciated.