The one I knew with the broken jaw also did it in the pasture and there was a human witness. Horse was turned out in a one acre paddock with one other known to get along with it. Four board fencing, good repair, lovely weather. Horses in their usual pairs in adjacent paddocks.
Apparently, horse had its head and neck stuck through the fence between the boards and sort of wrapped around a fence post trying to get that one perfect sprig of grass in the next paddock. Need I say grass was identical in all aspects and amount in all paddocks.
Anyway, it’s turn out buddy came over to see if there was something it was missing out on, got too close, horse pulled its head up suddenly forgetting about the boards, cracked it’s head and then panicked and spun into the fencepost smacking the side of the head on it breaking the jaw and 3 boards plus knocking the fencepost half out of the ground. If the groom hadn’t seen it, never would have known why it picked a fight with the fence.
My own mare, for some inexplicable reason, chose to roll in a bare spot right next to the fence on ground sloping into the fence. She got cast up against the fence post believe it or not, took 4 stitches on her shoulder just above the forearm. Fence was unharmed and we spent quite awhile trying to figure out how she cut herself so bad, never found a thing.
Poor Bear, I bet he hurts pretty bad since he did perk up a bit with the heavier drugs. They are bagging him aren’t they?