Here’s a great article about the honking noise that dogs make sometimes. I’ve seen this in many dogs over the years and never knew exactly what it was.
Reverse sneezing in dogs is a disconcerting event in which a dog makes an alarming respiratory sound, similar to a honking noise. This weird noise understandably leads pet owners to think that their dog is having trouble breathing or is choking and in grave danger. These episodes are followed by a warp-speed drive to the ER where we generally assess a happy dog wagging his or her tail and giving us the look of, “Not sure what all the fuss is about, but boy, that sure was a fun car ride!”