Effect of xylazine, detomidine, and a combination of xylazine and butorphanol on equine duodenal motility
Merritt, A.M.; Burrow, J.A.; Hartless, C.S.
American Journal of Veterinary Research 59(5): 619-623
1998
ISSN/ISBN: 0002-9645 PMID: 9582967 Document Number: 487810
Four healthy adult horses with an indwelling gastric cannula, with one horse also carrying 2 long-term indwelling bipolar electrodes sutured onto the duodenum and jejunum, were used in a study to evaluate the effect of some analgesic agents on equine duodenal motility. To ensure an empty stomach, solid food was withheld from horses for around 20 h before an experiment. Using video-endoscopic guidance, an 8-F catheter with 3 small, discrete pressure sensors was passed through the gastric cannula and directed into the proximal portion of the duodenum. Deflection of the recording pen, to which the catheter was attached, indicated a motile event in that section. Drugs (treatment) were given into the jugular vein in a randomized block design, 1 treatment/experiment, after a 1-h baseline recording. Treatments were: 2 ml of 0.9% NaCl, xylazine (XYL, 0.5 mg/kg body weight), detomidine (DET, 0.0125 mg/kg), or a xylazine/butorphanol combination (XYB, 0.5/0.05 mg/kg). Each horse received each treatment twice. All positive pressure peaks >5 mm of Hg recorded from the most proximal sensor on the catheter were counted in 15-min blocks. Each mean 15-min posttreatment value was compared with the baseline value for that specific treatment. There was no significant difference between baseline values. All treatments significantly reduced frequency of pressure peaks below their respective pretreatment values, but to variable degrees and durations. Comparatively, XYL had the least effect, with mild, though significant, reduction for only the first 30 min after treatment; DET and XYB caused a significant marked reduction for 1 h after treatment. It is suggested that the profound suppressive effect of a routine dose of detomidine or xylazine/butorphanol combination on equine duodenal motility must be considered when using these agents for management of colic.