Answer Thursday! Kovu here is demonstrating a reverse sneeze! This can be a scary thing, especially when it happens suddenly, but it is actually harmless and should resolve on its own in a few minutes. Often we don't know the cause of reverse sneezes, especially for those dogs that do it regularly, but some possibilities can be excitement, eating or drinking, exercise intolerance, pulling on a leash, mites, pollen, foreign bodies caught in the throat, perfumes, viruses, household chemicals, alle