Antagonistic Effects of Atipamezole and Yohimbine on Sedation Induced by Medetomidine in Dogs

Abstract

Antagonizing effects of atipamezole (ATI) or yohimbine (YOH) on sedation by medetomidine (MED) were examined in 18 normal dogs. All dogs of three groups were given an intramuscular injection of MED (60μg/kg B.W.), then 40 min later, dogs of group I received ATI (240μg/kg B.W., i.m.), dogs of group II received YOH (110 μg/kg B.W, i.v.), and dogs of group III (control) received saline solution (0.1 ml/kg B.W. i.m.) .
After MED injection, mean times to sedation and recumbency in all dogs were 3.2 min and 7.2 min, respectively. Mean times from ATI, YOH and saline injections to stand were 9.2, 19.1 and 63.5 min, respectively. Mean times from the injections to walk in three groups were 9.2, 20.8 and 88.2 min, respectively. The changes in heart rates, respiratory rates, blood pressure, body temperature and blood glucose levels were not significantly different between groups I and II.
From these results, it is suggested that the administration of ATI or YOH reversed the MED-induced sedation rapidly, and that the effect of ATI revealed a more certain and smooth than YOH.