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)