Endoscopic ultrasonography (EUS) examinations were performed with a radial ultrasonographic gastrovideoscope in 14 healthy, anesthetized beagles in order to characterize the appearance of the canine esophagus.
Images were obtained at 3-cm intervals along the esophageal length to allow evaluation of the esophageal wall with the probe in direct contact with the esophageal wall and with a water-filled balloon as a standoff. Images were obtained both with (12 dogs) and without (10 dogs) the water-filled balloon. Median thickness of the esophageal wall was 2.19 mm (range, 1.03 to 5.62 mm) in the proximal third of the esophagus, 2.15 mm (range, 1.10 to 4.45 mm) in the middle third and 2.84 mm (range, 1.35 to 5.92 mm) in the distal third. Wall thickness differed significantly between proximal and distal thirds. Results were similar when the water-filled balloon was used. Esophageal wall layers appeared as five alternating hyperechoic and hypoechoic bands that could not be consistently identified in all dogs. All layers could be identified in 26 of 198 (13%) images, three layers could be identified in 67 of 198 (34%) images, and 105 of 198 (53%) images had no layers. Visual identification of layers in images obtained with and without the balloon did not differ significantly.
In conclusion, EUS appeared to be a useful technique for assessing esophageal wall integrity in dogs; however, complete evaluation of all layers could not be accomplished in all instances. Further studies with this technique in dogs are needed.
Source: Penelope A. Baloi et al., 2013. Endoscopic ultrasonographic evaluation of the esophagus in healthy dogs. AJVR online, July 2013. doi: 10.2460/ajvr.74.7.1005