Here's what we know about feral hogs so far:
The original hog was either from Fukushima or Chernobyl plants.
It has the ability of quantum teleporation.
It spread it's radiactive seed among many wild hog populations around the world, leading to devastating attacks on humans.
The hogs are extra-dimensional warrior-race of conquerors and they came becasue they know humans are now able to face them in fair battle.