In my home, vegan take it or vegan leave it..
On a more serious note, I did listen to a radio interview once where a young woman was insisting that all animals could be vegan if only zoos would raise them from birth on plant products and not allow nursing or other animal products. They kept trying to explain to her that those who are not natural plant eaters, like cats, dogs and such, can't survive on a plant only diet, but she refused to be swayed insisting it was just because they didn't try.