The preanesthetic properties of
medetomidine, a novel alpha 2-adrenergic agonist, were compared to the preanesthetic properties of
acepromazine, zylazine and
meperidine prior to
halothane anesthesia. The
premedications were given to 23 randomly selected laboratory beagles in doses with
sedative effects equal to the 10 micrograms/kg used in the
medetomidine group. These dogs also received 0.04 mg/kg of
atropine prior to the preanesthetic. A group of 7 dogs with a high
medetomidine dose (40 micrograms/kg) was included in the study. Cardiopulmonary and respiratory parameters were recorded
at 10 min intervals during surgical stimulus. Dogs receiving 40 micrograms/kg of
medetomidine showed
bradycardia, but higher blood pressures than dogs in the other groups. Adequate
oxygen saturations and perfusion were recorded in all groups. The low 10 micrograms/kg dose of medetomididine had a
halothane sparing effect comparable to the other
premedications, while the 40 micrograms/kg of
medetomidine group showed a clear decrease in
halothane consumption. The
sedative effect of 10 micrograms/kg of
medetomidine was in some instances inadequate for proper manipulation of the dogs, but 40 micrograms/kg produced excessive sedation.
Atropine was found to counteract the
medetomidine induced
bradycardia.