Reverse sneezing in dogs

A normal sneeze expels air through the nasal cavity.

Its far more alarming to hear your dog reverse sneeze or backward sneeze. It sounds like the dog is struggling to breath.  It will be breathing in rapidly, making a loud snorting gagging sound. This lasts for a short time, meanwhile the dog is bringing air into his body to help remove an irritant that is far up in the respiratory tract behind the nose.

This is not uncommon for dogs and said to be more common in breeds with short muzzles.

Backward sneezing is not harmful and your dog will appear normal before and after a reverse sneeze.
Most dogs never get treated for this condition. If your dog reverse sneezes often you may want to check with your dog's Veterinarian for possible causes.