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Effects of repeated anaesthesia with ketamine/medetomidine and of pre-anaesthetic administration of buprenorphine in rats

Hedenqvist, P., Roughan, J. V., Flecknell, P. A.
Laboratory animals 2000 v.34 no.2 pp. 207-211
rats, anesthesia, ketamine, medetomidine, analgesics, narcotics, preoperative care, duration, mortality, combination drug therapy, dosage
Two groups of rats were anaesthetized at weekly intervals for 6 weeks with either ketamine/medetomidine alone (60 mg/0.4 mg/kg i.p.) or ketamine/medetomidine (45 mg/0.3 mg/kg i.p.) one hour following buprenorphine (0.05 mg/kg s.c.). Animals that received buprenorphine had longer periods of surgical anaesthesia (P = 0.04) and a greater depression of both mean pedal withdrawal score (P < 0.01) and mean respiratory rate (P = 0.014). Mean total duration of anaesthesia was also greater in the buprenorphine group on day 1. Sleep times reduced with successive doses of anaesthetic in the buprenorphine group (P = 0.024). Two animals in the buprenorphine group died. Repeated anaesthesia with ketamine/medetomidine alone was not associated with anaesthetic mortality. These results indicate that although buprenorphine has a clear anaesthetic-sparing effect, its use with ketamine/medetomidine may be associated with an increased risk of anaesthetic-related mortality.