Who is your best friend? No doubt, she's someone you love and trust, with whom you share a strong connection, who provides you with warmth and caring. But unconditional positive regard? Nah. For that you might have to invest in a relationship with a friend who has a claw, a paw or a feather. Studies show that taking care of a living thing is also a great way to exercise your compassion muscle. See how much you know about the positive effects of owning a pet.