A controversial question is whether it is God's plan for animals to be in heaven or not. Many Christians believe that heaven just would not be heaven without animals. Certainly I believe that the Creator of millions of different species of animals, birds, insects and fish is a God who loves variety and prizes His creation. I cannot believe that Heaven will only be populated by angels and saints. From a careful study of the Bible I have become convinced that Heaven will be richer in vegetation and animal life than the most paradise-like part of earth could ever be. Where people get the idea of harps and clouds from, I don't know. God has a far greater plan than we can imagine.
"This plan, which God will complete when the time is right, is to bring all creation together, everything in heaven and on earth, with Christ as head." Ephesians 1:10
"Wolves and sheep will live together in peace, and leopards will lie down with young goats, calves and lion cubs will feed together, and little children will take care of them. Cows and bears will eat together, and their calves and cubs will lie down in peace. Lions will eat straw as cattle do . . . The land will be as full of knowledge of the Lord as the seas are full of water." Isaiah 11:6-9
"Search in the Lord's book of living creatures and read what it says. Not one of these creatures will be missing and not one will be without its mate. The Lord has commanded it to be so; He Himself will bring them together. It is the Lord who will divide the land among them and give each of them a share. They will live in the land age after age, and it will belong to them for ever." Isaiah 34:16, 17
When the revealed Word of God teaches us that God's eternal plan is for "all creation" to be brought together under Christ then it includes all wildlife too. When God says "everything", He means everything - animals included.
When He says that they will live for "age after age", "forever", this means eternal life. Only one place will last forever, and that is Heaven.
That great book of worship in the Bible - the Psalms - reveals that all God's creation have contact with God (Psalm 93). All God's creatures praise Him (Psalm 145:10). It is only mankind who needs forgiving and saving and teaching as to how to worship (Psalm 36 & 51), the animal kingdom worships God continually and naturally.
"Praise Him, hills and mountains, fruit trees and forests; all animals, tame and wild, reptiles and birds." Psalm 148:9, 10
"Be glad, earth and sky! Roar sea and every creature in you: be glad fields and everything in you! The trees in the woods will shout for joy." Psalm 96:11, 12
The last book of the Bible presents the final climax of the ages when all creation faces the Creator. First the four living creatures (the animal-like angels around God's throne as described in Ezekiel) praise God, then the twenty-four elders, then the redeemed people of God, then the angels (Revelation 4:6 - 5:12), until finally the great scene is described when all living beings present their worship to Almighty God.
"And then I heard every creature in heaven, on earth, in the world below, and in the sea - all living beings in the universe - and they were singing: 'To Him who sits on the throne and to the Lamb, be praise and honour, glory and might, forever and ever'."
In the light of these Scriptures, I firmly believe that our loving almighty Creator intends all His creatures to enjoy heaven with Him forever. The only part of creation that will be missing from Heaven, according to the Bible, are those sinful human beings who neglect the great salvation that God has revealed in the Bible and provided through Christ. So while all the animal victims of scientific experiments will be in Heaven, the same cannot be said for all the hardhearted vivisectionists and ivory poachers.