A life shared with pets brings many emotions. We feel love for our companions, certainly, and happiness at the thought that we're providing them with a safe, healthy life. But there's another emotion, less often acknowledged, that can be nearly as powerful: guilt. When we see our cats gazing wistfully out the window, or watch a goldfish swim lazy circles in a bowl, we can't help but wonder: are we doing the right thing, keeping these independent beings...