We're sorry to hear about Sadi, and know the pain you are feeling, as we've been there all too often ourselves.
And, thank you very much for writing. Many people are asking the same questions?
From everything we've learned and studied, there will be more animals than we can count in heaven. There is nothing in the Bible that says that animals don't understand salvation, and don't communicate with the Holy Spirit in ways we don't understand; in fact, we know that God spoke with a donkey, with a great fish, and with birds, and who knows how many other animals that we are not told about. So, we're sure that Sadi will be in heaven, too, and perhaps even your other dog in a new glorified body that is free of the torment of this world that you saw as being so negative.
We also believe that all of the food animals will be there, too. It's the humans that will be held accountable for the horrible things that were done to them.
All of us have fallen short of the glory of God. What counts now. is how we live before God, and turn away from our formerly sinful ways.
We hope this helps.
In the Love of the Lord,
Frank and Mary