I don't know specifically if pets will be in heaven, but I do know what the bible says about all creation in general:
"For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,
Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.
For we know that the whole creation groaneth and travaileth in pain together until now.
And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body." - Romans 8:20-23
Vs. 20-21 talks about the deliverance of 'the creature". Most places in the bible the word "creature" refers to non-human entities (whether animals of spiritual beings as in Ezekiel 1:20).
But although there are some places that do refer "creature" to human (Mark 16:15, II Cor. 5:17), I do not believe it is the case in the above passage, because of the statement in bold, "Not only they" refers back to the creatures delivered from the bonds of corruption. This is not to say that they will be delivered from sin (since animals don't sin), but from the curse of death associated with sin. "But ourselves also" are in addition to the creature and refers to those who have that firstfruits of the Spirit, i.e. saved humans.
The animal creatures referred here will be experience the same redemption of the body, from death that is the bondage of corruption, just as humans will, as the whole creation groaneth.
Ergo, animals will be resurrected.