Well, I had not heard of it. A neighbor asked the question this past week; the context of the question was this: She had been told, as a child, that when animals die they go to "the rainbow bridge" in heaven and wait for their masters; supposedly to be reunited when the owner passes. May seem innocent enough to soothe a child but I got the impression that this was comforting for her to this day. I was a bit unnerved in that the assumption is made that the masters "are" going to heaven.

Although in pains me to do so, I'll leave off the evangelical aspect for a moment and focus on animals. Though I'd never heard of the rainbow bridge, I did have this question posed to me by a Christian before; He was an animal lover and was concerned about their place in heaven. My answer to him was that God has promised "His Children" abundant life here and something far better afterwards. The following scriptures enter into such a conversation:

He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things? Romans 8:32

The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid; and the calf and the young lion and the fatling together; and a little child shall lead them. Isaiah 11:6

I am confident that our God wants us to be joyful now and then enjoy something far greater on the other side.
Now to the most important thing; we must be sure that we are right with God, that is; we must "know" that we have eternal life.

These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.1 John 5:13

For whosoever shall call upon the name of the Lord shall be saved. Romans 10:13

Many individuals have pets that are like family. We must be careful that they don't become idols. I enjoy birds, specifically, purple martins but, it is essential that we yield to God and let His will be done in regard to the realm of heaven. Remember, He has our best interest at heart.