We were hiking in Virginia a few weeks ago and a guy told us a story from his hog-hunting friend in eastern Arkansas:
Guy was walking along when a hog came out of nowhere, hit him hard from behind and flipped him onto his back. Hog turned on him, pinned him down, ripped up his right arm and would have done more. The man was able to get hold of his gun with his left hand and shoot the hog.
I haven't seen a feral hog, but I'm more scared of them than a bear.