By Elias Ayala (MDiv & M.A.T.)
Unfortunately the Bible is silent on this topic and so anything I can provide will be by way of speculation. However, I think the speculation that will be expressed here can go a long way in answering the question.
While the Bible does not explicitly touch on our question, the Bible does have much to say in regards to the nature of man. Biblically understood, man is composed of body and soul. There is a physical and immaterial aspect to man. At death, these are separated. On the biblical view, death is not when someone ceases to exist, indeed, it is the separation of the body and the soul. The soul goes with God and the body is buried in the ground. The Bible explains: “…we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord” (2 Corinthians 5:8).
It seems that the biblical testimony is that one can be “absent” from the body and “be at home with the Lord”. This is a clear indication of conscious existence after death. However, in the case of animals, it is not at all clear what happens to them when they die. There seems to be strong indication that animals do not have souls in the sense that humans have souls. This is one of the key differences between the beasts and those created in the “image of God” (Genesis 1:26).
One important entailment of being created in the image of God is seen in our ability to reason and use logic. Human beings can contemplate ideas and even reflect upon one’s own existence. This is profoundly different than what we know about animals. Animals perceive and react to external stimuli, but it is the image bearer of God that asks “why”?
If animals lack an immaterial aspect to their natures (i.e. souls), then it seems as though there is no way for animals to survive death, since death for animals is unlike death for humans. While death for humans is the separation of body and soul; for animals, death would indeed be a ceasing of existence.
So it seems to be the case that believers who die and go to be with the Lord will most likely not see Spike the dog in heaven. However, that is not to say that there will NOT be animals in heaven. We need to remember that believers who go to heaven to be with the Lord will not be there forever. The Bible speaks of God creating a “New Heavens and New Earth” (Revelation 20:4). When we experience our bodily (physical) resurrection, we will dwell upon a physical earth that is united with heaven in which the dwelling place of God will be with men. In this new creation, there may very well be animals; although, not the very same animals that we had as pets on this earth.
Lastly, suppose there will be no animals at all in the New Creation. Let us remember that in this New Creation we will be perfectly united and have tangible physical presence with Jesus himself, and to that, we will find perfect fulfillment even better than any companionship one could have with an animal.