Evaluation of the analgesic effect of pentazocine on chlorpromazine-ketamine anesthesia in rabbits (Oryctolagus cuniculus)

Abstract

This study compared the quality of anesthesia produced by chlorpromazine-ketamine and chlorpromazine-pentazocine-ketamine in five healthy New Zealand White rabbits (6 to 12 months old and body weight 2.0 ± 0.3 kg, mean ±SD) using a crossover experimental design. Rabbits were premedicated with chlorpromazine intramuscularly (IM) at 10 mg/kg, and anesthesia was induced 30 minutes later with ketamine IM at 50 mg/kg (C-K). Two weeks later, the rabbits were similarly treated but received pentazocine IM (10 mg/kg) immediately after immediately after (C-P-K). Heart and respiratory rates (HR RR) and rectal temperature (RT) were recorded before induction and then at ten-minute intervals for two hours. The time to loss of the righting reflex, onset and duration of analgesia and recumbency and time to stand were calculated. Data are presented as the means ± SDs and were analyzed by Student’s t test and analysis of variance for repeated measures. A P value ≤ 0.05 was considered to indicate statistical significance. Compared with the C-K protocol, the C-P-K protocol resulted in a significantly longer duration of recumbency (118.6 ± 8.19 min; p = 0.0008) and a duration of analgesia (70.8 ± 13.08 min; p = 0.0001) (75.6 ± 15.11 min and 12.4 ± 13.57 min, respectively). Both protocols resulted in comparable recovery times. Compared with the C-K protocol, the C-P-K protocol resulted in significantly greater reductions in HR, RR and RT. However, with the exception of RT with the C-P-K protocol, these values were within the physiological limits for rabbits under anesthesia. In conclusion, the C-P-K protocol resulted in longer anesthetic and analgesic durations and may be useful for painful procedures of moderate duration in rabbits.