Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Veterinarians in practice are constantly encountered with young dogs presented with a history of persistent dysphagia and/or regurgitation since weaning. Persistent dysphagia and regurgitation implies the continual inability to swallow solid foods and the pass the formed bolus normally through the esophagus to the stomach; where it is digested enzymatically and physically to a liquified state, allowing the passage through the pyloric sphincter into the duodenum.
Carlisle, William T. and Egger, E. L.
"Differential Diagnosis of Persistent Dysphagia and Regurgitation in the Young,"
Iowa State University Veterinarian: Vol. 42
, Article 5.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol42/iss1/5