I am not really sure if a dog laughs or not, however my dogs definitely do smile. I also am convinced that my dogs try to make me laugh. The reason that I think that they intentionally try and make me laugh is that when they do something cute and/or funny and I laugh as a reaction, they always seem to repeat the same behaviour that made me laugh immediately after the first time. Then they will keep doing the same thing. Sometimes when I am sad I believe that my Golden Retriever picks up on it because she will take a good long look at me and then start up her silly antics again as if she is trying to pull me out of my bad mood. Dogs are amazing!