Effects of xylazole alone and in combination with ketamine on the metabolic and neurohumoral responses in healthy dogs

Objective To evaluate the effects of xylazole (an analogue of xylazine), also known as Jingsongling, alone and in combination with ketamine, on metabolic and neurohumoral responses in healthy dogs. Study design Prospective randomized experimental study. Animals Twelve healthy mongrel dogs (7 male, 5 female, aged 13-20 months, weighing 12.8-15.4 kg). Methods Each dog received one of two treatments: xylazole 4 mg kg-1 (group X n = 6); or xylazole 4 mg kg-1 plus ketamine 10 mg kg-1 (group XK; n = 6) intramuscularly. Pulse rate (PR), mean arterial pressure (MAP), respiratory rate (f(R)), and rectal temperature (RT) were recorded before and from 5 to 100 minutes after drug administration. Venous blood samples were taken before and at intervals from 0.5 to 24 hours after drug administration for determination of plasma concentrations of norepinephrine, epinephrine, beta-endorphin, cortisol, insulin, and glucose. Statistical analyses employed anova for repeated measures for changes with time and anova for comparison between treatments. Results In both treatment groups. PR, f(R) and RT decreased. MAP increased transiently. At some time points PR, MAP and RT were significantly lower in group X than group XK. Plasma norepinephrine, epinephrine, and insulin concentrations decreased, and beta-endorphin and glucose concentrations increased with both treatments. Higher values of plasma norepinephrine, epinephrine, beta-endorphin, and glucose concentrations were observed in the XK group compared with the X group. Conclusions and clinical relevance This study demonstrates that xylazole administered alone or in combination with ketamine in healthy dogs results in physiological, metabolic and neurohumoral responses similar to those seen after xylazine. Compared with xylazole alone, the combination of xylazole and ketamine reduced some of the responses.