Now we do have laws with regard to animals, based on the fact that they cannot show consent -- we can't be cruel to them, even if we do eat them. I think a case can be made that actual bestiality should be against the law. OTOH -- to take a relatively benign example -- some cartoon joke playing off the urban myth that Catherine the Great did it with a horse... Well, no animals were harmed in the making of the picture.
Torture is a touchier subject.... If someone is actually being tortured I could question their sanity... OTOH, there are other people who do physically grueling things that involve a lot of pain -- and some of them enjoy that. Think of the "Runner's high" some athletes get.
I think though that if you hit a level of mutilation that is permanently and seriously disfiguring or maiming, the victim has crossed a line where their sanity can be questions. And if insane, again, they are not capable of consent.
But again illustrated depictions have to be allowed -- heck much religious art is based on the depiction of people undergoing severe torture.