Dogs with severe tracheal flattening exhibit lower degrees of left lateralization of the cervical esophagus.

Herein, we investigated the positional relationship between the cervical esophagus and trachea using computed tomography (CT) images in dogs with tracheal flattening. From these CT images, the ratio of the tracheal diameters in the short (vertical) and long (horizontal) axes of the tracheal ring (S/L ratio) and the vertebra-trachea-esophagus (VTE) angle were measured at the point from the 3rd cervical (C3) to the 3rd thoracic vertebra (T3) levels. The VTE angle in dogs with tracheal flattening with an S/L ratio under 0.24 tended to be smaller than the angles at the level from C4 to T2 in dogs with an S/L ratio over 0.25. The positional relationship between the esophagus and trachea seems to be possibly related to tracheal cross-sectional shape.