10 year old Maltese Terrier

Findings

On radiographs, there is generalized cardiac enlargement. The trachea is elevated and is parallel to the spine. The left atrium is enlarged, causing a triangular area of soft tissue opacity on lateral radiographs and double density sign on the d/v. The vessels appear normal. There is no evidence of heart failure at this time. There is a small amount of air in the cervical and thoracic esophagus. The trachea appears normal.
A fluoroscopic study of the trachea was performed, during which the dog was induced to cough with tracheal pressure.

On fluoroscopy, the terminal portion of the trachea and both main stem bronchi collapse during coughing.