My Beagle has a 'backward sneeze' almost every day. He begins to heave and appears to be choking. It scared me the first time it happened so I went to the Internet to look for answers. It was a huge relief to find that this behavior is not an emergency, so I could relax. There are several videos on the internet showing different breeds having a 'backward sneeze'.
There are a few things you can do if this happens to your dog. The only thing new that I have to offer that seems to help a little:
When the 'sneeze' seems almost over, allow you dog to lick a small amount of butter or margarine from your fingertip.
If you do nothing, the event will stop with none the worse for your dog.