Animals, any animal, may develop a prejudice for a number of reasons; in OP's example of the 'naturally racist' dog, it could even be something simple, like the dog thinking anyone not Caucasian is not part of his family, or something. My aunt breeds bull mastiffs, and has taken a few in as rescues; one had been abused so horribly that in addition to a hefty vet bill right out of the gate, the dog was terrified of men and men's shoes. Turns out the former owner (a man) used to kick the dog frequently when he would beat it. That dog fell in love with my aunt, but would growl at and cower from my uncle, who would *never* hurt an animal. That poor dog couldn't be retrained, so my aunt kept it, and she was the only one the dog trusted; the dog never warmed up to any male. It just demonstrates that a dog tries to figure out how the world works as best it can; some are afraid of men, others of Blacks, others with a red bandana...whatever that animal has put together in its head as being the key to staying safe, being loved, and doing 'right' by its pack-family. So no animal is really 'being racist', not in a real sense, like some humans. It may never make sense to us, but on some level, it makes sense to them.