They don't mutilate,,,they remove them. If they are not breeding males, which they don't need to be, they DON"T NEED THEM! It also makes for a happier dog. He has none of the problems of having to deal with intact females in heat and also he will be healthier dog.
Being a male myself, I find that hard to accept. Nearly all of the neutered males that I have seen are fat and lazy. Like they have no hope and nothing to live for.