Sedative effects of medetomidine in pigeons (Columba livia)

The sedative effects of medetomidine administered alone or in combination with ketamine or midazolam were evaluated in 20 adult pigeons (Columba livia). Six to 12 pigeons were randomly assigned to each of 5 treatment groups. Medetomidine administered alone (80, 150, or 200 mug/kg IM) caused effects ranging from ataxia to sternal recumbency, but the righting reflex was always retained. The level of sedation resulting from medetomidine (80 mug/kg IM) in combination with either ketamine (5 mg/kg IM) or midazolam (0.5 mg/kg IM) was variable; birds exhibited signs ranging from mild to heavy sedation. Heavy sedation was defined as loss of the righting reflex and profound muscle relaxation. Medetomidine-ketamine resulted in heavy sedation in 3 of 9 birds, whereas 5 of 12 birds were heavily sedated with medetomidine-midazolam. Atipamizole (0.5 mg/kg IM) was administered to reverse the effects of medeton-tidine. The length of time (mean SD) from atipamizole injection until loss of ataxia and return of full responsiveness ranged from 10 +/- 4.0 to 17 +/- 5.0 minutes with medetomidine alone. Birds sedated with medetomidine-ketamine recovered within 20 +/- 12.0 minutes, and those sedated with medetomidine-midazolam recovered within 38 +/- 11.0 minutes. Atipamizole was given 30 minutes after administration of medetomidine alone and medetomidine-ketamine, whereas birds given medetomidine-midazolam received atipamizole 50 minutes after administration. Medetomidine used alone or in combination with ketamine or midazolam cannot be recommended for sedation of pigeons at the dosages described in this study. Used alone, medetomidine was inadequate for restraint, and when administered with ketamine or midazolam, sedative effects were unpredictable.