Evaluation of the effect of hyoscine-N-butyl bromide on the cardiovascular actions of detomidine in the horse

Twenty one adult horses, males and females, were pretreated with 0.14 mg/kg of hyoscine-N-butylbromide intravenously and injected 5 minutes later with 0.02 mg/kg, iv of detomidine (group A, n = 9) or saline (group B, n = 12). Mean arterial pressure measurements and electrocardiography were performed during 65 minutes. After hyoscine injection the heart rate was increased by 43% and 65% in A and B groups, respectively. Heart rate remained increased after injection of detomidine, returning to baseline values after 15 minutes. No increase in the mean arterial pressure (MAP) was noticed after hyoscine but the MAP was increased by 62% after detomidine, returning to basal measurements until the end of observation time. No additional increase was noted in the group B horses. Hyoscine shortened PR and QT intervals in both groups, but after detomidine, PR and QT intervals enlarged significantly at the end of the experiment. The second degree atrioventricular block occurred in 3 horses after 40 minutes only in group B. It was concluded that hyoscine prevented detomidine induced bradycardia and may be an useful drug combination against the bradycardia induced by this alpha-2 agonist, in horses.

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Bibliographic Details
Main Authors: VALADÃO,Carlos Augusto Araújo, TEIXEIRA NETO,Francisco José, MARQUES,José Antônio
Format: Digital revista
Language:English
Published: Faculdade de Medicina Veterinária e Zootecnia / Universidade de São Paulo 2000
Online Access:http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1413-95962000000500011
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