Comparison of intramuscular alfaxalone with medetomidine-ketamine for inducing anaesthesia in Trachemys scripta spp. undergoing sterilization

Objective To compare the effect of two anaesthetic protocols on heart rate (HR), time to muscle relaxation and tracheal intubation and time to surgical plane of anaesthesia, in Trachemys scripta spp. undergoing oophorectomy.Study design Prospective randomized clinical study.Animals A total of 43 healthy female turtles.Methods Morphine (1.5 mg kg(-1)) was injected subcutaneously 2 hours before anaesthesia induction. The turtles were randomly administered either medetomidine (0.2 mg kg(-1)) and ketamine (10 mg kg(-1)) (group MK; n = 23) or alfaxalone (20 mg kg(-1)) (group A; n = 20) intramuscularly followed by bupivacaine (2 mg kg(-1)) administered subcutaneously along the incision site. Anaesthesia was maintained with isoflurane delivered in oxygen (100%). HR and the anaesthetic depth score (ADS) were recorded every 5 minutes from induction to recovery. A Friedman test followed by Wilcoxon tests with Bonferroni adjustment were used to compare these non-parametric data (HR and ADS) between groups and over time. Time to muscle relaxation of neck and limbs (T-MR), tracheal tube insertion (T-TTI) and stage of surgical anaesthesia (T-ADS=3) were recorded and compared between groups using a Welch's t test after logarithmic transformation.Results Median values of T-MR, T-TTI and T-ADS=3 were 4, 9.5 and 25 minutes in group A, respectively, and 14, 20 and 35 minutes in group MK (T-MR, T-TTI p = 0.0001; T-ADS=3 p = 0.001). Plane of anaesthesia was significantly deeper in group A than in group MK for the first 20 minutes (p < 0.01). HR at 10 and 15 minutes post injection was significantly lower in group MK (28 beats minute(-1)) than in group A (36 and 34 beats minute(-1)) (p < 0.02).Conclusions and clinical relevance After intramuscular injection in Trachemys scripta spp., tracheal intubation, muscle relaxation and a surgical plane of anaesthesia developed faster with alfaxalone than medetomidine-ketamine.