Gastrointestinal motility disorders affect the nerves and muscles of the esophagus, stomach, and/or the intestines, causing digestive disturbances. Congenital idiopathic megaesophagus (CIM) is an esophageal motility disorder of dogs wherein contractility is reduced and leads to an enlargement of the esophagus. Affected puppies regurgitate after eating and survivors are susceptible to life-threatening complications. The highest incidences of CIM occur in the Great Dane and German Shepherd Dog breeds. Gastric dilatation-volvulus (GDV or bloat) is characterized by dilatation and twisting of the stomach, cutting off blood and oxygen to the organs. Based on a previous study for CIM in Great Danes, the investigators will 1) study a narrow region of chromosome 6, shown to be a major risk factor for CIM; 2) seek additional genomic regions that contribute to CIM, and 3) determine association between CIM and GDV based on shared genetic risk factors that impact gastrointestinal motility. The investigators hope to establish a pattern of transmission and develop a genetic test to reduce the incidence of CIM, and potentially GDV, in Great Danes.