Well, I guess I have to take many of you to task here. Don't you know that rape is a crime of violence, not of sex? Did you sleep through your Women's Studies classes?
If a rapist is castrated or has his genitalia removed or chemically neutralized or whatever, he can just use a stick or broom or bottle or some other tool or implement to continue the violence.
In fact, in this news story, it said he sodomized the dog with a bottle before raping her.