I am not saying that it is unconscionable to FORCE the dog into marriage. Quite the opposite. I am saying that while a man is entitled to marriage as a civil right, a dog is not. There is no reason why the government should grant the dog the privilege of getting married.
The man is out of luck, and needs to find a marriage partner who also is entitled to marriage by right.
Avi K, I have heard your solution proposed before, and I like it. Why does the government need to be involved in marriage in the first place? Let people get married on their own, and the benefit system can be dealt with completely separately.
Incest and polygamy are significantly stronger arguments for the “slippery slope” than bestiality. Critics, though, would probably say that they are illegal because there is a “legitimate state interest” in preventing both those things– incest, because it will create children with birth defects or abnormalities, and polygamy, because the government will have to provide health insurance benefits for multiple spouses.