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

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-pathogenfree 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 micrograms/kg of body weight; medetomidine, 80 micrograms/kg; xylazine, 2 mg/kg; butorphanol, 200 micrograms/kg; ketamine, 10 mg/kg; and atipamezole, 240 micrograms/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.