First info on Shaggy: a six year old paso fino gelding redish in color, we feed him two flakes alfalfa for two feedings a day and he is in a "pasture" (nothing I believe he would want to eat is in it) with 2 other horses, and another horse in a "pasture" next to his - all two other horses are older than him. He is allergic to flies, but it only is bad on his face so we only have him wear a fly mask, with ears so the flies don't bite them either. Not liking them ear takes them off and basically destroys them.
Here are a couple images of the wound. (Links)
Shaggy - Full Face, left Side - please ignore person, focus is the horse
Shaggy - Close up of wound, left side - thumb for size reference
The white stuff on his face is not part of the wound, but Swat ointment for wounds and sores. I have yet to take a picture of it before I put the ointment on. I also know that wounds on horses take awhile to heal, so please do not remind me on this.
My parents believe that he has received this wound by rubbing one of the fly masks that we recently put on him because he was trying to get it off and got it caught on something. The wound is on the spot that the edge of the fly mask lands.