Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for Izzie.
As you may already know, reverse sneezing, is considered a normal reflex to an irritant in the posterior (the nasopharynx). Any nasal, pharyngeal, or sinus irritation can result in a reverse sneeze.
When a dog only occasionally reverse sneezes, then I don't worry about it too much. I'll often suggest that owners give over the counter Benadryl (Diphenhydramine) for episodes such as Izzie is having. The dose would be 1 mg per pound of body weight twice a day with sedation a possible side effect.
When (or if) the condition becomes chronic (because is doesn't in most patients), then the following are possible explanations:
1. Nasal mites but may be difficult to find.
Treatment is fairly easy, though, with Ivermectin given every week for three doses. I'll often treat my patients for these mites before pursuing any additional testing.
2. Foreign bodies such as a blade of grass or foxtail. Often sedation with rhinoscopy is needed to detect such a problem.
3. Allergies or rhinitis/sinusitis which may be more challenging to diagnose without additional testing but response to medication can often help to rule them in or out.
4. Polyps or masses which are best diagnosed with an MRI and possible rhinoscopy and resultant biopsy.
6. Lower airway diseases can result in secretions that are coughed up; these may irritate the nasopharynx resulting in a reverse sneeze.
At this point, if she were my patient, I'd give her Benadryl as I mentioned which may be all she needs to stop this behavior.
I hope this helps. Deb