This is a beautiful shot! I love horses and feel you captured this horse beautifully.
I really love the strength of the horse. I really love the contrast the dark/light tones here. The white stripe and the white hair on the legs are beautiful contrast with the dark hair on the horse.
The wind!!!! The wind and the way that the hair is blowing is so beautiful! The posture/stand of the horse is perfect.
I like that my eyes go directly to the horse and nothing distracts me in the photo. It looks like a storm is coming and I think that the gloomy feel to this photo fits perfect with the strength of the horse and you captured the overall strength of nature beautifully.
As for the fence, I really like that its there. It does not distract me what so ever! Because of the strong points of the horse and nature my eyes go past the fence. The fence makes me feel like the horse is safe in some way. Protected and nurtured by humans. If the fence wasn't there it would make me think its a wild horse but no wild horse would stand that close to a human.
Overall a brilliant shot!