Anesthesia induced in pigs by use of a combination of medetomidine, butorphanol, and ketamine and its reversal by administration of atipamezole

Abstract

Objective - To develop an IM administrable anesthetic combination for pigs. Design - Use of a combination of atropine, medetomidine, butorphanol, and ketamine (MB-K) was evaluated as an anesthetic regimen and compared with that of a combination of atropine, xylazine, butorphanol, and ketamine (XB-K). Cardiorespiratory effects of MB-K combination and use of atipamezole as a means of reversing anesthesia induced by MB-K were examined. Animals - 18 castrated, mixed-breed, specific-pathogen free pigs, aged 8 to 15 (mean, 12.1) weeks and weighing 14.5 to 26.0 (mean, 19.6) kg, were studied. Procedure - Dosages of drugs used in this study were atropine, 25 μg/kg of body weight; medetomidine, 80 μg/kg; xylazine, 2 mg/kg; butorphanol, 200 μg/kg; ketamine, 10 mg/kg; and atipamezole, 240 μg/kg. Results - MB-K combination proved to be more effective than XB-K combination as an anesthetic combination. After quick and smooth induction by IM administration, MB-K-induced anesthesia was sustained for 98.8 ± 22.5 minutes (mean ± SD, 47.4 ± 16.5 minutes by XB-K) with accompanying muscular relaxation (91 ± 18 minutes) and loss of pedal (82 ± 24 minutes) and laryngeal (75 ± 19 minutes) reflexes. Loss of these reflexes was of significantly longer duration than the loss induced by XB-K, enabled tracheal intubation, and, thus, supported major surgery for at least 30 minutes after induction. Recovery from MB-K-induced anesthesia was smooth. MB-K combination had a slight stimulative effect on cardiovascular status, and a significant depressant effect on blood gas and acid-base status, but these effects were within biologically acceptable limits. Oxygen consumption of pigs under MB-K-induced anesthesia decreased significantly. MB-K-induced anesthesia could be effectively and quickly reversed by IM or IV administration of atipamezole. Conclusions - The combination of medetomidine, butorphanol, and ketamine induces excellent surgical anesthesia in pigs, and results in moderate cardiorespiratory effects. A great advantage of the anesthetic regimen is that it can be effectively and quickly reversed by atipamezole. Clinical Relevance - Medetomidine, butorphanol, and ketamine-induced anesthesia is available for short-term major surgery in pigs.