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

Abstract

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-mduced 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. (Am J Vet Res 1996;57:529–534)