The Bible does not say what happens to animals when they die. What we do know is animals have a special place not only in man’s past and present, but also in his future. God cares for them and not one dies without His noticing (Matthew 6:26, 10:29). God created animals and saw that they were good (Genesis 1:20-25), brought them to Adam to see what he would call them (Genesis 2:19-20), and assigned man the responsibility of taking care of them (Genesis 1:28).
But animals are not created in the same class as man. That’s why we do not know if the animals in heaven would include those that have died on earth. Man will be in heaven because he is created in the image of God (Genesis 1:26-28, 2:7).
We do know that everything God has given us on earth helps us understand and receive what He has in store for us in heaven. Every opportunity for love and care we have shown for God’s creation will be rewarded with greater opportunities to give and receive love. There will be no grief or sorrow in heaven. Every need will be met, and we will be filled with overflowing joy.
We don’t know if our pet will be in heaven, but God knows. And that’s what is important, because His plans are always best, and He desires to do for us more than we could ask or think (Ephesians 3:20).