A shih tzu that displays a fit of coughing, sneezing or snorting and who may appear unable to breathe could actually have a very minor diagnosis of: Inspiratory Dyspnea. This is not Kennel Cough and should not be mistaken for it. This has to do with the physical structure of the shih tzu, and the incomplete closure of the nasopharnyx (above the soft palate). It is Inspiratory Dyspnea, commonly referred to as "reverse sneezing," or a type of air hunger.
Swallowing will help stop the attack.
So how can I help my shih tzu swallow during these attacks?
The easiest way to make a dog swallow is place your thumb or fingers over the nostril openings and rub the throat area, and slightly open the mouth. This should cause a relief almost immediately. It is important that you understand whether or not the "reverse sneeze" is the problem and not something more serious. If closing the nostrils and swallowing corrects it, this is probably what it is.
Always report the problem to your vet and tell him what you did when the attack occurs to be absolutely sure the "reverse sneeze" is the proper diagnosis for your particular shih tzu.
If it happens when you are not home, don't worry, they can and do recover without your assistance to help them swallow. If you do find this procedure helps your shih tzu, they may learn to run to you (when you are home)for help.
There are many serious health problems that can cause coughing, congestive heart failures, pulmonary disease, kennel cough etc., so make sure the cause of the cough is this inspiratory dyspnea and not something more serious by always reporting the problem to your vet for further evaluations.