I see that he is a bit back at the knee, and maybe a tad "bench kneed", from the front angle.
I am intrigued that other people picked up on his facial expression being one of possible abnormaility or discomfort. My initial impression was of a horse that is in pain, somehow, with the flaired nostril and the kind of tight jaw. I can not put my finger on it, but that was my first impression , of a hrose not relaxed or comfortable, but rather "enduring" something. and I had that impression before reading anything written by others. Could he be in any pain? it's very odd that I had that impression, but I am not alone.