Analgesic Efficacy and Safety of Buprenorphine in Chinchillas (Chinchilla lanigera).

Buprenorphine is routinely used in chinchillas at reported doses of 0.01 to 0.1 mg/kg IM or SC. However, these dose recommendations are based on anecdotal reports or extrapolation from studies in other species. Therefore, the purpose of this study was to evaluate the analgesic efficacy and safety of subcutaneously administered buprenorphine in chinchillas. Using a randomized, blind, controlled, complete crossover design, we evaluated buprenorphine at a single dose of 0.05, 0.1 or 0.2 mg/kg SC (experiment A) and 0.2 mg/kg SC (experiment B). Analgesic efficacy was determined by measuring limb withdrawal latencies in response to a thermal noxious stimulus (Hargreaves method) at 0, 3, 6, 12, and 24 h (experiment A) and at 0, 1, 2, 4, and 8 h (experiment B). In a third experiment, food intake and fecal output were monitored after repeated administration of buprenorphine (0.2 mg/kg SC every 6 h for 3 doses). Buprenorphine at 0.2 mg/kg SC, but not at 0.05 or 0.1 mg/kg SC, significantly increased limb withdrawal latencies for less than 4 h. Self-limiting reduction in food intake and fecal output occurred after administration at the 0.2-mg/kg dose in animals undergoing algesiometry. In chinchillas not undergoing algesiometry, the administration of 3 doses at 0.2 mg/kg SC every 6 h did not reduce food intake but significantly decreased fecal output for the first 24 h. Additional studies are needed to evaluate buprenorphine in different algesiometry models and to establish its pharmacokinetic profile in chinchillas.