Pretty sure for those to be entry/exit wounds it’d need to have gone through bone. He wouldn’t be up and walking around if that were the case. The supposed “entry” wound is too ragged to be a bullet or pellet, gunshot entry wounds are the exact size/shape of the bullet.
Likely the canine teeth of some other animal that got a hold of his snout.
It’s a health textbook, of course it’s stuck in the 1950’s