Equi, he's short striding and hunching up ever so slightly in the back. Plus, the parked out stance tells me there's something wrong. A horse should never just randomly park out like that.
It may be several issues, but I'm pretty sure his stifles are sore and he may have a kidney problem.
Couldn't respond before the thread was closed about not seeing his hind end looking wonky - I have had horses for a while, but only one mare ever gave me trouble when it came to being unsound through her rear, and she hid her lameness well. She was a gaited mare, and two different vets told me that was the reason she moved like she did, but it just looked wrong and I had a bad feeling so I had one more vet assess and sure enough, she had ligament problems in her back end. That is the only horse I've ever seen sore up in her rear! Maybe I have just been blessed with healthy and sound horses. :) Can you explain to me how he looks "wonky"? I'd really like to be able to recognize it. Thanks!