The Reverse Sneeze Explained

                             Dr. James St.Clair from Top Dog helps to clarify this puzzling sound.
Dogs tend to be resilient creatures, but when the pups we love make odd, wheezing-like sounds while reverse sneezing, it’s hard not to worry about what’s happening to them.   But please do not panic.
So What Exactly is a Reverse Sneeze? 
A reverse sneeze — also referred to as a “backward sneeze” — is characterized by the “sudden onset of a dog extending his head and neck and making rapid inspiration movements with the mouth closed, that results in noises coming from the nasal passages.”
Although the alarming episodes typically last only seconds, they can feel like a lifetime to some owners — especially if they’re witnessing it for the first time.
Why does it Happen?  We are not 100% certain but here are some ideas and my (Dr.L) own experience.
Dogs either sneeze normally or reverse sneeze depending on where the irritation occurs in their noses. “A reverse sneeze, like a regular sneeze, is a reflex, but instead of a rapid expulsion of air through the nostrils, it is a rapid inhalation.  It is loud, so people often think that their dogs are having an asthma attack. Dogs don’t have asthma attacks, so it’s usually suggestive of reverse sneezing.” In some cases, repetitive reverse sneezing could stem from irritation of the nasal and pharyngeal passages due to a chemical irritant or an allergic reaction. The culprit could also be a foreign material that’s stuck to the back of the nasal area, such as a blade of grass. If you suspect that your dog inhaled something foreign, contact Dr.L.   Remember that a reverse sneeze will occur with your dog’s mouth closed. A cough or a regular sneeze occurs with your dog’s mouth open.  I had the opportunity to examine a dog under fluoroscopy while doing my residency and observed a reverse sneeze from the “inside”.  It appeared that the epiglottis (a structure in the back of the mouth), was caught above the soft palate,(the soft part of the roof of the mouth) and the dog started to reverse sneeze. As soon as the dog swallowed, the reverse sneeze stopped.
Is there any Reason to be Concerned?  NOT USUALLY .
Just like a cough or a normal sneeze, a reverse sneeze is designed to expel whatever irritant has triggered it. Like a regular sneeze, the occasional reverse sneeze is considered perfectly normal.  In my experience, (Dr.L), normal, healthy dogs can do this at any time. 
Some dogs start reverse sneezing at a young age and continue to do so on occasion throughout adulthood without any problems. But if the reverse sneezing starts later in life, increases in frequency and severity, or is accompanied by other signs such as a bloody or mucus discharge from the nose, call Dr.L.
What can I do to Help my Dog?
You generally do not have to do anything for it to stop.  If you feel inclined to do something,  gently massage the throat area. You can also lift up your dog’s neck to make it straight while gently blowing into it’s nose. Ultimately, the reverse sneeze will subside on its own when your dogs swallows.
I hope this helps to clarify this puzzling sound.  Dr.L