Pets are people, too.
My sister's dog Chewy may not know it, but he's a human. Maybe because he hasn't spent much time around other dogs he thinks he's just like us, but we can definitely sense his moods and feelings every day. He gets happy, angry, frustrated, sad and tired just like the rest of us! And I think it helps us relate to him and keep him happy by thinking of him in terms of how we would treat other people.
This might sound cheezy, but Chewy is just as much a "person" in our family as any of us.