Okay, here goes the debate...

First, as far as it being "consentual" for the animal. I personally believe that if a dog is trying to hump you to begin with that is pretty much telling me that he wants something. And that he needs something. And it isn't a doggy bisquit. The question, if you are going to go about this, that you should be asking yourself (if you have any doubts about "consent") is basicly... is the animal attempting to retreat or is he (sorry, can only speak for males because that is all I have experience with) going for it? Common sense will tell you if an animal (or a person) is enjoying something or not. You don't need words to know if a human is enjoying something... why would you need them for an animal? Seriously, I am not saying everyone needs to grab their dog and "do it" but to say that it is animal abuse or to say that there is no way to tell whether the animal truly wants it or if it is consentual or not is a little ridiculous to me. I can't even count the times I have seen an animal try to force themselves on a person humping their leg and other displays of affection. But, then, maybe that's just me.