Dana, people who tell you that animals have no souls do not understand the
nature of the Universe. The Universe is, in and of itself, sentient and
alive. Everything that is alive is part of it, everything participates in
what we call "soul," or "spirit." It would be impossible for an animal to
be born without a soul, though perhaps, a severe accident to animal or
human may cause fracturing of soul and body.
I do not believe, personally, in the concept of heaven as taught generally, but rather, in other planes or dimensions of existence that souls move to between reincarnations. Loved pets are there as well as ancestors.
Dan the mystic