Evaluation of Xylazine, Acepromazine and Medetomidine with Ketamine for General Anaesthesia in Rabbits
A randomized, prospective, blinded experimental study was conducted in 32 rabbits of either sex to compare the anaesthetic and physiological effects of ketamine with different pre-anaesthetics. Rabbits were randomly divided into 4 equal groups. Xylazine 6 mg/kg in animals of group xylazine-ketamine (XK), acepromazine 2 mg/kg in animals of group acepromazine-ketamine (AK), medetomidine 125 μg/kg in group medetomidine-ketamine 1 (MK1) or medetomidine 250 μg/kg in group medetomidine-ketamine 2 (MK2) were administered by intramuscular injection (IM). Five minutes later, ketamine 60 mg/kg was administered intramuscularly to all the groups. The rabbits were observed for the onset of weak time, down time, the time to loss of righting reflex, pedal reflexes and response to surgical stimuli. Heart rate, respiratory rate and rectal temperature and arterial oxygen saturation of haemoglobin (SpO2) were recorded up to 60 min. Weak time, down time and time to loss of righting reflex were the shortest in animals of group MK2 as compared to the other groups. Pedal reflexes remained intact in all the animals of XK group, but were abolished in 50% of the AK group, 75% of the MK1 group and 100% of animals in the MK2 group. Pain was evinced during surgery by all the animals in group XK, 5 animals in group AK and 4 animals in group MK1. The best analgesia was achieved in the animals of group MK2, where none of the animals showed pain on surgical stimulation. Heart rate and SpO2 decreased significantly (P<0.01) in the animals of groups XK, MK1 and MK2 but respiratory rate and rectal temperature decreased significantly (P<0.01) in all the groups. However, all the animals recovered from anaesthesia without complications. It was concluded that medetomidine 250 µg/kg and ketamine 60 mg/kg produced excellent anaesthesia to allow pain free surgery and may be considered suitable for anaesthesia in New Zealand White rabbits.