CS Lewis remarked in a few different places that dogs and cats pick up a certain amount of humanity from associating with us, and the best of them pick up a lot from being in a good human family. In Screwtape he has the demons noting angrily that everyone who associates with a certain Christian household acquires the "stink" of holiness after awhile. It's not difficult to suppose that those humans who are faith-filled can somehow spread their reflected holiness to the animals they love. As the unbelieving husband is sanctified by the believing wife, per Paul (1 Cor 7) might not our animals be imbued with our love so that they can enjoy eternity with us?
One of my favorite C.S. Lewis quotations (from _The Great Divorce_ and discovered on a FR thread) where he describes a woman in heaven surrounded by children, angels, birds and beasts:
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What are all these animals? A cat - two cats - dozens of cats. And all those dogs ... why, I cant count them. And the birds. And the horses.
They are her beasts.
Did she keep a sort of zoo? I mean, this is a bit too much.
Every beast and bird that came near her had its place in her love. In her they became themselves. And now the abundance of life she has in Christ from the Father flows over into them.