Someone made a point in regards to the cat in an earlier post ( can't recall who it was).

So I went back and re-watched the episode. The more I think about it the more I am convinced that the cat was symbollically supposed to be Christopher re-incarnated. He stares at Christopher's picture, and one can easily make an argument that it could be Adrianna because of this. However he could be staring at himself, remembering when. But what really makes me lean towards it being Chris is the fact that the Cat totally annoyed Paulie. Just like Chris used to. The Cat got under Paulie's skin. Just like Chris used to. Tony loved the Cat. Just as he loved Chris. And when Paulie is sitting all alone outside of Satriale's, there's the Cat sitting right there also. Just like Chris and Paulie used to do.

I'm convinced that the Cat was symbolic of Christopher.