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Abstract

Objective—To determine blood flow patterns in the common carotid artery and external jugular vein in cows before and after sedation achieved by administration of xylazine hydrochloride.

Animals—30 clinically normal Swiss Braunvieh cows.

Procedure—A 5.0-MHz sector transducer was used to examine the common carotid artery and external jugular vein before and after cows were sedated by administration of xylazine. Several variables were calculated, including diameter of the blood vessels, blood flow velocity, and flow-time volume.

Results—The common carotid artery before sedation had a maximum systolic velocity of 89 ± 8.5 cm/s, maximum diastolic velocity of 36 ± 6.0 cm/s, mean velocity of 35 ± 5.4 cm/s, and flow-time volume of 28.2 ± 3.48 cm³/s. In all cows, sedation achieved by administration of xylazine resulted in a significant decrease in velocity of arterial blood flow and flowtime volume. The external jugular vein before sedation had a maximum velocity of 65 ± 8.3 cm/s, maximum velocity of retrograde venous blood flow of 20 ± 6.6 cm/s, and flow-time volume of 29.7 ± 5.42 cm³/s. These values decreased significantly after cows were sedated by administration of xylazine.

Conclusions and Clinical Relevance—Doppler ultrasonography is particularly suitable for evaluation of blood flow patterns in the common carotid artery and external jugular vein of healthy cows. The results reported here provide a basis for use in examination of cows with cardiac and blood vessel disease. (Am J Vet Res 2005;66:962–965)

Summary

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.

To determine reproducibility and reliability of the results, 10 cows were examined by ultrasonography 10 times within 2 weeks. The interassay coefficients of variation determined from these examinations varied from 3.0 to 12.3%; most of the coefficients of variation ranged from 5 to 10%. The smallest coefficients of variation were determined for diameter of the common carotid artery, and the largest were for diameter of the external jugular vein.

Description of the ultrasonographic appearance of the structures of the ventral neck region in healthy cattle represents the basis for use of diagnostic ultrasonography in cattle with suspected diseases involving this area. The technique is noninvasive and can be performed on cattle in standing position.