10 year old Fox Terrier

Findings

There is an oval mass dorsal to the trachea in the cranial neck. It extends from C2 to C5. There is an irregular gas lucency through the mid-area of the mass, and the caudal aspect is also outlined by gas in the esophageal lumen.
On sagittal and transverse ultrasound images, the mass is homogeneous with an irregular gas pattern that is contiguous with the esophageal lumen. The mass is an expansion of the esophageal wall.