This is an interesting question about animals and heaven.
I also cannot imagine heaven without the dogs I have owned or taken care of. And for loved human beings, words cannot express my hope for them to be there.
Perhaps thinking of heaven in a different way from “somewhere we go when our bodies die” can be helpful. Perhaps we should think more of heaven as coming to earth and redeeming it. Bible scholar N.T. Wright has something to say about this in his book “Surprised by Hope”, chapter 6, section “The marriage of heaven and earth” which I quote here:
We thus arrive at the last and perhaps the greatest image of new creation, of cosmic renewal, in the whole Bible. This scene, set out in Revelation 21-22, is not well enough known or pondered (perhaps because, in order to earn the right to read it, one should really read the rest of the Revelation of St. John first, which proves too daunting for many). This time the image is that of marriage. The New Jerusalem comes down out of heaven like a bride adorned for her husband.
We notice right away how drastically different this is from all those would-be Christian scenarios in which the end of the story is the Christian going off to heaven as a soul, naked and unadorned, to meet its maker in fear and trembling. As in Philippians 3, it is not we who go to heaven, it is heaven that comes to earth; indeed, it is the church itself, the heavenly Jerusalem, that comes down to earth. This is the ultimate rejection of all types of Gnosticism, of every worldview that sees the final goal as the separation of the world from God, of the physical from the spiritual, of earth from heaven. It is the final answer to the Lord’s prayer, that God’s kingdom will come and his will be done on earth as in heaven. It is what Paul is talking about in Ephesians 1:10, that God’s design, and promise, was to sum up all things in Christ, things both in heaven and on earth. It is the final fulfillment, in richly symbolic imagery, of the promise of Genesis I, that the creation of male and female would together reflect God’s image in the world. And it is the final accomplishment of God’s great design, to defeat and abolish death forever - which can only mean the rescue of creation from its present plight of decay.
Heaven and earth, it seems, are not after all poles apart, needing to be separated forever when all the children of heaven have been rescued from this wicked earth. Nor are they simply different ways of looking at the same thing, as would be implied by some kinds of pantheism. No, they are different, radically different, but they are made for each other in the same way (Revelation is suggesting) as male and female. And when they finally come together, that will be cause for rejoicing in the same way that a wedding is: a creational sign that God’s project is going forward; that opposite poles within creation are made for union, not competition; that love and not hate have the last word in the universe; that fruitfulness and not sterility is God’s will for creation.
It’s not necessarily that I’m a universalist - it seems that Satan and his angels will be utterly destroyed - but I can imagine that heaven could contain redeemed versions of all of God’s good creatures. For an infinite God, there shouldn’t be an issue with space for a finite number of creatures . And perhaps we will only need Jesus to sustain us, or we will only need flora as food. Isaiah 65:25 says “The wolf and the lamb will feed together, and the lion will eat straw like the ox…” As for mosquitoes, I can imagine an extension to this principle as the human co-habiting with the mosquito . And no, I don’t know how a Tyrannosaurus Rex is going to eat vegetation with those teeth .