Actually he's pretty dang good. Two things to watch for if doing a head shot like this one again is the neck. While its true some people do have long and/or thick necks, when it comes to drawing you want to under-exaggerate them to get them to look right. Here the only place I would have worked on with the neck though as around the lower jaw area.I'm really bad at drawing people, and my Pat does looks kinda bad.
The other, the bane to most 3D modelers, is the ears. They are ALWAYS a pita to do, hence why you often see lots of ways to simply hide them. Sure its the whimps way out but its also a perfectly valid one too. In your case neither are all that bad either. All in all your Pat is really good but your horse, your horse is great!