Reverse sneezing is exactly what it sounds like: instead of forcefully expelling air through the nose, your dog will forcefully inhale through the nose. This will cause a lot of snorting and wheezing and can be pretty alarming the first time it happens. However, generally this is nothing to worry about and doesn’t have any negative effects on your pooch. Known clinically as paroxysmal respiration, reverse sneezing is completely harmless and there are no bad effects on your pet. Sometimes it may seem like your dog has something large caught in his or her throat, but that’s not the case. An “attack” might last a few seconds to a minute or two.
The cause of reverse sneezing is not known. However, the problem seems to be exacerbated by allergies and environmental irritants like smoke, potpourri, cologne, and pollen. Dogs with longer noses and narrower nasal passages tend to be more susceptible to attacks of reverse sneezing.
Diagnosis
Reverse sneezing is generally diagnosed by clinical signs and your pet’s medical history. Your veterinarian will attempt to rule out other conditions that cause snorting and abnormal breathing such as upper respiratory tract infections, nasal tumors or polyps, and more. He or she might also recommend allergy tests or x-rays.
Treatment
Generally there is no treatment required for reverse sneezing. In the event of an attack, you can stroke your dog’s neck to calm him or her down. Usually attacks end with a hearty exhale through the nose. If allergies are a contributing factor, your veterinarian might prescribe anti-histamines or nasal decongestants.
– See more at: http://www.pethealthnetwork.com/dog-health/reverse-sneezing-dogs