Can an Animal be a Somebody?

Chris in Northampton, Massachusetts, and his mother are debating whether you can refer to your dog as somebody? Is it reasonable to say your pet is a someone rather than a something? Strictly speaking, dictionaries define the word someone as referring specifically to human beings. But Chris would argue that there’s an exception when it comes to our relationship with companion animals. Also, is it improper to use the relative pronoun who instead of that when referring to a pet? And does that usage change when you’re talking about wild animals? This is part of a complete episode.