The use and assessment of ketamine-medetomidine-butorphanol combinations for field anaesthesia in wild European badgers (Meles meles)

OBJECTIVE: To evaluate the effectiveness of four ketamine-based anaesthetics in badgers using a quantitative anaesthesia assessment technique. STUDY DESIGN: Prospective randomized 'blinded' experimental trial. METHODS: The quality of induction, of anaesthesia (at 5-minute intervals) and of recovery were assessed in 93 badgers, given either one of three ketamine (K)-medetomidine (M)-butorphanol (B) combinations: group A - M K B at 20/40/80 microg kg(-1); group B - M K B at 20/40/60 microg kg(-1); and group C - M K B at 20/60/40 microg kg(-1), or ketamine (K) alone at 2 mg kg(-1) (group D). The assessor was ignorant of the combination administered. Physiological variables (heart and respiratory rates and rectal temperature) were measured at 5-minute intervals during anaesthesia. Gingival mucus membrane colour was also recorded. RESULTS: Induction to anaesthesia was most rapid with ketamine (2 mg kg(-1)) although induction quality did not differ between techniques. Ketamine used alone gave the poorest score for anaesthesia quality. Heart rate (HR) and scores for gingival mucus membrane colour were higher in animals anaesthetized with ketamine alone. Rectal temperature did not differ significantly between the techniques at any time during anaesthesia. Ketamine used alone produced the poorest quality of recovery. CONCLUSION AND CLINICAL RELEVANCE: The M-K-B combinations investigated overcame several side effects associated with ketamine anaesthesia, but at the expense of more variable induction times, lower HRs, and poorer mucus membrane coloration.