I do not think your dog has a hole in the esophagus--this means that food would travel outside the esophagus and into the surrounding tissue--this would cause a lot of secondary problems aside from gagging.
Small dogs are prone to collapsing trachea and stenotic trachea both of which can cause coughing sounds that sound like gagging. These little dogs should be walked on a traditional collar--a harness is used to prevent pressure on the trachea.
Heart disease--both congenital and acquired can cause coughing that can sound like gagging.
Developmental problems with the soft palate (roof of the mouth) can also lead to gagging.
There are other disease processes that can lead to gagging--if this is related to nausea.
I would get another veterinarian's opinion about this dog. He needs an examination, x-rays, and possibly bloodwork to see if this gagging problem is treatable.
Small dogs are prone to collapsing trachea and stenotic trachea both of which can cause coughing sounds that sound like gagging. These little dogs should be walked on a traditional collar--a harness is used to prevent pressure on the trachea.
Heart disease--both congenital and acquired can cause coughing that can sound like gagging.
Developmental problems with the soft palate (roof of the mouth) can also lead to gagging.
There are other disease processes that can lead to gagging--if this is related to nausea.
I would get another veterinarian's opinion about this dog. He needs an examination, x-rays, and possibly bloodwork to see if this gagging problem is treatable.