We don't give our golden retrievers a comfortable life and then kill and eat them. They don't want to die for that. Why do we treat pigs and cows differently?

We don't give our golden retrievers a comfortable life and then kill and eat them. They don't want to die for that. Why do we treat pigs and cows differently? Pigs have even scored higher than dogs on some intelligence tests. I found Melanie Joy's book on the related human history and psychology helpful here: Why We Love Dogs, Eat Pigs and Wear Cows.