I got my dog from a reputable breeder. Is this ethical? I sometimes feel guilty that I didn’t adopt a shelter dog instead. —Anonymous

There is much to be said for adopting a shelter dog, but taking on a pet you don’t want isn’t the way to do it. As a dog lover who worries about abandoned animals, however, you probably should contribute to organizations that may reduce their numbers.

—Adapted from ‘The Ethicist’ in The New York Times Magazine.