I agree, and I would love to believe that my 'lil babies will see a better rebirth based on their affection for my family.
The Theravada position on this seems a little ambivalent. On the one hand, you have the stories in the Commentaries (eg the toad who was reborn as a deva, the Paleilai monkey and pachyderm, Eravana's promotion to the Heaven of the 33).
Yet, I'm told that the Kathavatthu says that these stories are not to be taken literally, but as allegories. The objection was something along the lines that the heavens have no place for menageries, or something like that.