Why do dogs sneeze

I'm just curious about why my dogs sneeze when they are playing with eachother.

Actually, it's mostly after they have had a very vocal growling match.

Any idea?

I think when they lift their lips up, it closes their nostrils a bit and then it feels like they have something in their noses... So they sneeze. My theory. :)

Certain breeds of dogs and cats have compressed nasal passages due to their conformation. Any of the dogs breed that snore (Pekingese, pugs, bulldogs, Lhasa Apsos, Shia Tzu etc.) share this problem.
Dogs do sneeze, however, generally from some irritation in the nose. Some dogs sneeze from excitement or nervousness that stimulates the nerves in the nasal passages. Many Akitas make “happy sneezes” after greeting a favorite person or playing.

Some dogs sneeze from excitement

Yup, that's what it sounds like to me. Definately from excitement.

I just thought it was curious, that's all.

My dad's sheltie sneezes when he gets excited. He'll only bark a little bit, but he'll sneeze up a storm.