Antagonism of detomidine sedation in the horse using intravenous tolazoline or atipamezole.
BACKGROUND
The ability to shorten the duration of sedation would potentially improve safety and utility of detomidine.


OBJECTIVE
To determine the effects of tolazoline and atipamezole after detomidine sedation.


OBJECTIVE
Administration of tolazoline or atipamezole would not affect detomidine sedation.


METHODS
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.


RESULTS
Atipamezole and tolazoline administration incompletely antagonised the effects of detomidine, but the time course to recovery was shortened.


CONCLUSIONS
Single bolus administration of atipamezole or tolazoline produced partial reversal of detomidine sedation and may be useful for minimising detomidine sedation.
Hubbell
J A E
JA
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, 601 Tharp Street, Columbus, Ohio 43210, USA.
Muir
W W
WW
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006736:Horses / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000037:antagonists & inhibitors*; D007093:Imidazoles / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D007262:Infusions, Intravenous / Q000662:veterinary; D007700:Kinetics; D012449:Safety; D014043:Tolazoline / Q000494:pharmacology*; D014743:Videotape Recording
D006993:Hypnotics and Sedatives; D007093:Imidazoles; C050701:atipamezole; C041255:detomidine; D014043:Tolazoline