I answer that, Since the renewal of the world will be for man's sake it follows that it should be conformed to the renewal of man.
If the renewal of the world is for man's sake, then is it not possible that God will re-create the forms of our beloved pets and establish them in a state worthy of the renewal?
This, I believe, is the current teaching: that the pets get to heaven inasmuch as we need them there.
My theology, while too revolutionary to be orthodox, is much simpler and wholly scriptural: they already are in Heaven, because they never left it.