Nice pictures, a couple of thoughts:
1. The head/neck of the other horse is a little distracting. Perhaps some cloning/cropping to eliminate? I like the main subject, but it appears just a tad over-exposed
2. A greatt picture except for the blown highlights. A reduction of probably 1 1/2-2 stops and then a levels tweak would have helped greatly.
3. I love the expression on this guy's face, unfortunately, with his friend behind him, it makes for a rather confusing image.
In cases like this with a large dynamic range, check your camera's settings against the daylight exposure rule, or maybe try bracketing. Overall, nice animal pictures!