If animals can't make an informed choice about sex with humans, then they can't make an informed choice about vivisection, either. Some animals can arguably make a choice about fetching the ball, but only "arguably," because if they were actually intelligent, they'd be aware that failure to fetch the bell, lick your feet, curl up in your lap, remain in the proximity of your property, et cetera, is likely to result in their imprisonment, surgical mutilation, and state execution without trial. They're under duress, it's Stockholm Syndrome, they're underage, they're food-dependent, et cetera.
We've decided that animal rights are subordinate to our own, since we torture them for cosmetic purposes (or humanely kill them for food), ergo banning sex with them in order to protect them is ridiculous. We could make the argument of protein requirements and the naturalness of the food chain, and if so, continue hunting and/or farming them, but if we permit anything else--execution without trial for sleeping on a city street; elective reproductive surgery without informed consent; enslavement and the wanton breaking-up of families--we might as well also permit bestiality, unless our argument is that we prohibit bestiality to protect ourselves, not the animals. If we're allowed to own and protect them because we know better, why don't we know better about that? Or should we be asking Hillary who and where we're allowed to screw?
The various herbivore-people aren't free of this analysis, for they consume microscopic animals which dwell on plants. They also destroy and rearrange animal habitats in order to farm to feed themselves (even if, as they claim, it's less-so than omnivores do), and, worst of all, they violate the rights of plants, which grow and respond to stimuli and reproduce also. If you can't beat dolphins because they're sacred, what makes spinach any less so? Did Yahweh give souls only to humans? Okay, then beat baby seals all day long. Did Yahweh give souls to humans and dolphins, but not yellowfin tuna? To bacteria? To sequoia? To romaine? Whose rights do you violate, and when?
One of the questions we need to ask ourselves is, "To what extent does anything else matter?" And if the dog's perspective matters, keeping it as a social comfort companion and permanently surgically altering its sex organs is far worse than keeping it as a social comfort companion and occasionally letting it knot Meth Debby, or, if we're combating meth or championing women, Farmer Frank.
Deathlord Yaldabaoth believes in torturing and sacrificing animals as a show of piety and glory, and following in his footsteps, we've developed this sort of satanically puritanical world where we may shave and then boil dogs alive for "science" in order to achieve preliminary results for whether or not a new kind of burn-relief cream will work on pigs, then humans, but we may not bring them to orgasm--except when the orgasm is performed without enjoyment on a drugged animal in order to produce future test subjects for the menthol-scented broilers. We're not allowed to kick them in public or leave them in the car, but we're allowed to lock them in a cage for 72 hours with a bowl of water while we drive to Tahoe for Labor Day.
Dealing with bestiality--more specifically, punishing the people who slashgasm mares, or restricting the people who pay Meth Debby to suck off rottweilers in highdef--will, if it's ever done, give rise to a lot of extremely unpleasant questions in our society. Degrees will still offer protection--concentration camp veterinarians will still be able to "neuter" and "spay" and "put to sleep" their victims, while people without the right degree who drown extra kittens will be prosecuted and/or looked upon as the scum of the earth. The preliminary sickness that we've permitted into our slave system will provide its best evidence to the zoos. After all, if Dr. Nguyen can execute and carve dogs at whim (and, in the human world, if Dr. Chabra can put Grandma to sleep when her medication gets too expensive), why can't Farmer Frank bugger his ol' tick hound now and then?
We've seen this before, with the many busy tentacles of the Catholic church and its work to protect the vulnerable worldwide. How retroactively ironic it will seem, in a hundred years, that the animal-loving petwardens created the world where animals could not only be house slaves and lab workers, but eventually, publicly- and legally-protected as expendable sex slaves. Their genitals are already the property of their owners; we've made it clear that cutting those off is completely acceptable.
If we end up enforcing bestiality laws, the only people we're protecting is ourselves, which is really sick and perverted, because it implies we want it and would be interested in it if only it were legal, ergo we need it to be illegal in order to keep us outta the barn. What do you say? Oh yeah--gross, dude.