title: Effects of xylazine butorphanol on cecal arterial blood flow, cecal mechanical activity, and systemic hemodynamics in horses.
abstract: A chronic model with an ultrasonic transit time blood flow probe and strain gauge force transducers implanted on the cecum was used to evaluate cecal mechanical activity and cecal arterial blood flow in 4 conscious adult horses. Intravenous administration of xylazine (1.1 mg/kg of body weight) significantly decreased heart rate and cardiac output, but significantly increased diastolic pulmonary arterial pressure, mean pulmonary arterial pressure, carotid arterial pressure, and central venous pressure. Lateral cecal arterial blood flow after xylazine administration was decreased substantially more than was cardiac output, suggesting that xylazine caused constriction of the cecal vasculature. This effect of xylazine may have resulted from either a direct effect of xylazine on the cecal vasculature or from reflex vasoconstriction attributable to reduced cardiac output. Intravenous administration of butorphanol tartrate (0.1 mg/kg) did not significantly alter the hemodynamic responses to xylazine. Cecal mechanical activity, as measured by the motility index, was decreased for 120 minutes after administration of xylazine and for 150 minutes after administration of xylazine/butorphanol.
authors.affiliation: Section of Surgery, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square 19348.
authors.forename: J A
authors.initials: JA
authors.lastname: Rutkowski
authors.forename: S C
authors.initials: SC
authors.lastname: Eades
authors.forename: J N
authors.initials: JN
authors.lastname: Moore
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002077:Butorphanol / Q000494:pharmacology*; D002302:Cardiac Output / Q000187:drug effects; D002432:Cecum / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects*; D004338:Drug Combinations; D005769:Gastrointestinal Motility / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006736:Horses / Q000502:physiology*; D008638:Mesenteric Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects; D014463:Ultrasonography; D014991:Xylazine / Q000494:pharmacology*
chemical_list: D004338:Drug Combinations; D014991:Xylazine; D002077:Butorphanol