Choanal Atresia Choanal Atresia Choanal atresia is a devastating congenital defect which is relatively common in llamas and very uncommon in other animals and people.
Choanal atresia is the lack of a connection between the nose and the mouth .
Normally, the nasal passages lead back into the pharynx which connects to the opening of the trachea which then leads into the lungs. The area where the nasal passages meet the pharynx at the end of the hard palate is called the choanae. Atresia is the absence of a normal opening. Therefore, choanal atresia is the lack of a normal opening at the choanae. There normal opening is absent because the bone or membrane present during embryonic development fails to break down .