I'm late coming in here and know your back out there again but good luck to the finish. The same thing happened to my son with a bull a couple of years ago. Knocked him flat and didn't move for about 15 seconds and then was up and running for as far away as he could see him, never found a spot of blood with that one either.
Sounds like one of the tougher areas to be hunting them in for sure. And you got some of the nastiest weather in the last month to do it in.
Good luck again.