Owwy

There is one problem with taking the horses out to pasture before daylight- you don't get a good look at them. I found an owwy on Beamer this afternoon after work- one of the reasons I didn't notice it  this morning when I put his halter on is that he always yawns just as I go to slip the noseband over. I did take some photos of him in the fog this morning, and downloaded them this afternoon before heading out to do chores. I was wondering what the heck as I looked through the photos of him going full tilt boogie:

Do you see it?

Warning- wound photo below.

Anyway, when I brought him in, this is what I found:

One tetanus shot later, and a vet appointment for tomorrow afternoon. We'll have to cut the big flap on the bottom off as it was much too late to try stitching.I cleaned it out as much as I could and put some Purification oil on it to hold until the vet can clean him up tomorrow. I fear this will alter his lovely profile a little.
Edited to add: After searching his pen for the culprit, the only thing I could find is a broken root with a sharp edge  right where he rolls. You know how they like to smoosh their face in the dust when they are rolling? Yeah.  I took my splitting maul to it and bust it into smithereens.