Ultrasonographic examination of the ventral neck region in cows.

The position, dimensions, and structure of the thyroid gland, the portion of the esophagus in the neck, the cervical lymph nodes, and the major blood vessels of the neck were determined via ultrasonography in cattle. The left and right ventral neck regions of 30 healthy Swiss Braunvieh cows were examined ultrasonographically, using 3.5- and 5.0-MHz linear transducers and a 3.5-MHz convex transducer. The external jugular vein was situated directly beneath the skin in the upper and middle parts of the neck and 2.7 to 6.6 cm from the body surface in the lower part of the neck. In contrast, the common carotid artery was located further from the body surface along the entire ventral neck region; depending on the measuring point, this distance varied from 2.6 to 10.9 cm. The external jugular vein narrowed from caudad to craniad. The diameter of the common carotid artery remained fairly constant along its course in the ventral part of the neck and varied from 0.9 to 1.4 cm. The thyroid gland was identified via ultrasonography caudodorsal to the larynx. It appeared as an echogenic spindle-shaped structure with finely granular echogenic pattern. The esophagus appeared as a band-shaped structure in longitudinal section, and it could be followed to the thoracic inlet. Its width increased from craniad to caudad, and mean +/- SD diameter was 2.9 +/- 0.23 cm. The medulla, hilus, cortex, and capsule of the cervical lymph nodes could be clearly differentiated via ultrasonography. Mean length and width of the left cervical lymph node were 3.0 +/- 0.45 and 1.8 +/- 0.23 cm, respectively.