What about a dog necessarily means that it lacks understanding of what it’s doing? Why can a dog not know what sex is? My dog can know what a bath is and that he wants one. So what about sex is something that dogs are incapable of understanding?

I don’t think it ALWAYS physically harms the dog just because it’s smaller. But let’s just talk about large dogs then. What if the human doesn’t care about being physically harmed by the dog? Or what if it just doesn’t physically harm the human? What about that situation would be harmful then?

I agree that you can’t personally help what you’re attracted to, but that acting on those things can be bad.