What if someone who was in love with you in a past life, but never had you, reincarnated as your dog?
Imagine that. A soul that loves your soul, so it chooses to live the short life of a dog, so it could bask in your affection. The affection we show our dogs, after all, often surpasses the affection we're comfortable showing other human beings. So maybe it would receive the type of unrestrained love that we sometimes only show other animals.
What if two souls decide to incarnate together as a puppy and the child to whom the puppy was given?
Just something I like to think about, since I have four dogs myself (: