I'm embarrassed to say that when I was younger I always celebrated my dog's birthday. One year I put on a birthday party, inviting three friends and their dogs. I bought a can of Chum dog food (the one that comes out of the can in a solid lump,) and upturned it on a plate with a candle in it. For a present I bought the dog a jumper and a set of little vinyl boots. Yes, yes, I know - but I was young and foolish. I don't do these things anymore...well aside from a Christmas present...