What I see is something with his back right leg. If you look at both of the pics his right leg seems to be postioned normal but to me the back left leg is stretched back in the first picture and then he seems to no be baring wieght on it in the second one. Maybe he has something wrong with that hip or has something wrong somewhere around the bottom of his leg. Just a thought. I have only had my horse for a little while but I sure have learned what looks normal and what does not.