Reversal of medetomidine sedation by atipamezole in dogs

Atipamezole reversed the sedative effect of medetomidine in twelve laboratory beagles. The dogs were sedated with medetomidine doses of 20, 40 and 80 micrograms/kg body wt i.m. Atipamezole was injected (i.m.) 20 min later at dose rates two, four, six and ten times higher (in micrograms/kg) than the preceding medetomidine dose. Placebo treatment was included in the study. The deeply sedated dogs showed signs of arousal in 3-7 min and took their first steps 4-12 min after atipamezole injection. The dose-related reversal effect of atipamezole proved to be optimal with doses which were four, six or ten times higher than the preceding medetomidine dose. Drowsiness was found 0.5-1 h after atipamezole injection in 41% of the cases. No adverse effects nor cases of over-alertness or excitement were found.