Effects of subarachnoid xylazine and medetomidine on haemodynamics and ECGin goats

The effects of subarachnoid administration of the alpha(2)-agonists xylazin e and medetomidine on haemodynamic parameters in six adult goats were evalu ated. Xylazine (0.05 mg/kg body wt) or medetomidine (0.01 mg/kg body wt) wa s 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 ce ntral venous pressure increased during this period. The ECG changes produce d by these drugs were bradycardia and increased PR and QT intervals. The st udy suggested that both alpha(2)-agonists depress haemodynamic parameters a nd produce comparable effects after subarachnoid administration.