I am going to get a lot of TD, I know.
You are having a party for you, the dog is just an excuse, and he won't care anyway! It's not like he's going to say, 'Hey, thanks for the cake, what are you going to buy me next year!?'
If you really want to celebrate getting a great dog, donate the money you would spend on a useless celebration that is all about YOU, (Your dog will not care, remember or look forward to it as much as you, be honest) and donate the money to a shelter for dogs, or starving children.
I love my three dogs. But dogs are not human beings. Save an animal, write a protest letter to your Government about the high kill rate of abandoned dogs, and the low fines for animal cruelty.
Or, you could make a meat cake, have his rich doggy friends over, and have a nice birthday celebration. What a waste of money!