I think the perspective is interesting, but it may be a little unbalanced. Typically, the space is given to where the subject is facing or heading, and you've done the opposite. While I appreciate work with broken rules, I'm not sure if this one works out that well...it may be because the background at the um..."ass end" is so bright and distracting from the subject.
Maybe this composition would work better if the horse anchored one end of the picture, serving a piece of a larger whole. Try using different backgrounds, ones that make it seem the horse did not belong in that position (on the canvas) without the backdrop and vice versa. Perhaps some very subtle action on the left side, clearly subservient to the horse, which it is "observing".
I don't know....just some thoughts. It's a good experimental piece.