Scavenger after death is my guess.
Neck on cow is stretched out like it had been pulled from the lower part of the throat near the shoulder after she was already down. Blood above the nose is probably where the flap was on the ground before the dog/cat grabbed what he had and left. It doesn't look like it came from the nose itself.
Throat area is very vascular, and there's little blood below the throat. This leads me to believe that the cow had already died and the heart wasn't pumping.
