There's nothing quite like a relationship with an aged pet--a dog or cat who has been at our side for years, forming an ineffable bond. Pampered pets, however, are a rarity among animals who have been domesticated. Farm animals, for example, are usually slaughtered before their first birthday. We never stop to think about it, but the typical images we see of cows, chickens, pigs, and the like are of young animals. What would we see if they were allowed...