I’ve had my boy for about a month and try to either ride or do ground work a few days a week. He’s very sweet and usually a pretty smooth ride. We have a few areas of his training that have been neglected (he struggles with the left lead etc) and he’s got sweet itch so towards the end of a ride he gets itchy and it shows. But generally he’s good. Last night we did a light hack out to our practice field and did some easy stick and ball at the walk and trot. After about an hour he just stopped. He would only turn right. Would not turn to the left at all. But he would stay next to my trainers horse and turn with her like he was being ponied. No pinning. No meanness. No stamping. No head tossing. Just a total refusal to do anything other than donuts to the right or follow the leader. Thoughts?

Edit1: “struggles” not in the sense that it’s off or he can’t do it. He just hard core defaults to right lead unless you ask in the middle of a turn to the left and make him pick up the left. My trainer tells me in his experience it’s not uncommon for argentine trained horses to be “right footed”

Edit2: he’s had a recent PPE including x rays.