Equine veterinary journal

Antagonism of detomidine sedation in the horse using intravenous tolazoline or atipamezole.

PMID 16706278


The ability to shorten the duration of sedation would potentially improve safety and utility of detomidine. To determine the effects of tolazoline and atipamezole after detomidine sedation. Administration of tolazoline or atipamezole would not affect detomidine sedation. In a randomised, placebo-controlled, double-blind, descriptive study, detomidine (0.02 mg/kg bwt i.v.) was administered to 6 mature horses on 4 separate occasions. Twenty-five mins later, each horse received one of 4 treatments: Group 1 saline (0.9% i.v.) as a placebo control; Group 2 atipamezole (0.05 mg/kg bwt i.v.); Group 3 atipamezole (0.1 mg/kg bwt i.v.); and Group 4 tolazoline (4.0 mg/kg bwt i.v.). Sedation, muscle relaxation and ataxia were scored by 3 independent observers at 9 time points. Horses were led through an obstacle course at 7 time points. Course completion time was recorded and the ability of the horse to traverse the course was scored by 3 independent observers. Horses were videotaped before, during and after each trip through the obstacle course. Atipamezole and tolazoline administration incompletely antagonised the effects of detomidine, but the time course to recovery was shortened. Single bolus administration of atipamezole or tolazoline produced partial reversal of detomidine sedation and may be useful for minimising detomidine sedation.

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2-Benzylimidazoline, 99%