Mystery lameness when horse changes rein at trot, HELP!

I have an 18 year old gelding that I’m bringing back into work after a couple months off due to lack of time. He has started displaying a mild hitch at the trot most noticeable when changing direction from right to left, but also intermittently noticeable when circling to the left. It is not evident when he is at liberty and he is very active and runs around and rears up and plays with the other horses. He does seem to work out of it a little but not 100%. I had a vet do a work-up on him and she injected his hocks and stifles. It is 3 weeks later and the hitch seems no better.

He has a history of arthritis in his fetlocks and hocks and a little bit stifles but has always been serviceably sound. He has lived out 24/7 for the past few years. He is barefoot behind. He does seem to be slightly sore in his back region and has been pinning his ears with grooming and being tacked up, but he has always been this way to some extent. He seems happy to work though and never objects to anything under saddle.

I spoke to the original vet and she recommended a chiropractic adjustment, which I’m going to go forward with, but I wanted to see if anybody has any other ideas. I’m worried it could be a soft tissue thing, but also was wondering if it could even be a dental issue.

Thanks

Getting a chiropractor and dental work done won’t do him any harm and will give you peace of mind.

Get a chiro out. Sounds like his hips could be out to me

I think chiro is a good idea. Also, a lot of the older horses do great with daily previcox