The truth is, the Bible doesn't really say whether or not our dogs will be in Heaven. I tend to think that they will, but in light of the lack of Biblical support for that belief, I'm willing to admit that it may just be sentimentality on my part.
On the other hand, it doesn't say they won't, either.
Some people will say, "Well, if you have to have your dog there for it to be Heaven for you, then God will arrange for your dog to be there".
I hear that one a lot, but I really can't imagine where it comes from. Heaven isn't about us. It's about God and His glory. It's true that Heaven will be a place of happiness and bliss, but that's because we'll be in God's presence and this blanket of sin will finally be lifted off of us, not because we'll have a cosmic genie to cater to our every need.
Nothing would make me happier than to see all the dogs I've loved in Heaven, but I think it's best to just leave that one up to God.