Effects of subarachnoid xylazine and medetomidine on haemodynamics and ECG in goats.

The effects of subarachnoid administration of the alpha 2-agonists xylazine and medetomidine on haemodynamic parameters in six adult goats were evaluated. Xylazine (0.05 mg/kg body wt) or medetomidine (0.01 mg/kg body wt) was administrated in the lumbosacral subarachnoid space. Mean arterial blood pressure and central venous pressure and electrocardiograms were monitored up to 120 min post-injection. Xylazine and medetomidine produced significant and comparable decreases in mean arterial blood pressure in the post-injection period. However, mean central venous pressure increased during this period. The ECG changes produced by these drugs were bradycardia and increased PR and QT intervals. The study suggested that both alpha 2-agonists depress haemodynamic parameters and produce comparable effects after subarachnoid administration.