Evaluation of three medetomidine-based protocols for chemical restraint and sedation for non-painful procedures in companion rats (Rattus norvegicus).

Three medetomidine-based protocols were evaluated for sedation in companion rats undergoing diagnostic procedures. Group Me received medetomidine at 150 μg/kg intramuscularly (IM); group Me-Bu received medetomidine 100 μg/kg IM and butorphanol 2 mg/kg IM, and group Me-Bu-Mi received medetomidine 50 μg/kg IM, butorphanol 2 mg/kg IM and midazolam 1 mg/kg IM. The righting reflex disappeared more quickly in the Me-Bu-Mi group, but recovery after atipamezole was longer. In group Me, a palpebral reflex was present throughout sedation in more rats than in the other two groups. Pulse and respiratory rates were higher when lower doses of medetomidine were used, although arterial haemoglobin O2 saturation was similar among groups. All protocols tested produced adequate sedation lasting 25 min.