Comparison of the Cardiovascular Effects of Two Medetomidine Doses Combined with Tiletamine-Zolazepam for the Immobilization of Red Deer Hinds (Cervus elaphus)

Wild animal immobilization often requires high doses of α2-adrenoceptor agonists. Despite their desired sedative and analgetic effects, well-recognized cardiovascular side effects, such as hypertension and bradycardia, remain a major concern. We compared two medetomidine doses on intra-arterial blood pressure and heart rate in 13 captive, female red deer (Cervus elaphus) immobilized during winter. Each animal was randomly assigned to receive either 80 μg/kg (group L) or 100 μg/kg (group H) medetomidine, combined with 3 mg/kg tiletamine-zolazepam administered intramuscularly. Changes in cardiovascular variables over time and differences between the groups were analyzed using linear mixed-effect models. Induction time was faster in group L compared with group H; recovery time did not differ between groups. Initially, the arterial blood pressure was higher in group H compared with group L, but differences between groups diminished during anesthesia. Moreover, the decline in arterial blood pressure in group H was more rapid. Heart rate was significantly lower in group L, but bradycardia was not observed. The higher medetomidine dose did not reduce induction time, and initial hypertension was reduced by administering the lower dose. Therefore, although the sample size was small and, thus, the significance of results might be limited, we suggest using 80 μg/kg instead of 100 μg/kg medetomidine when combined with 3 mg/kg tiletamine-zolazepam for the immobilization of female red deer.