Anaesthetic effects of various ratios of ketamine and xylazine in rhesus monkeys (Macacca mulatta).

Intramuscular injection of selected ratios of ketamine and xylazine provided smooth anaesthetic induction, a wide safety margin, and no significant undersirable side effects. Induction and recovery times, duration of anaesthesia, and thermoregulatory ability can be affected by different combinations of ketamine and xylazine. The addition of xylazine to ketamine increases muscle relaxation, recovery time, and duration of anaesthesia, while generally decreasing induction time and thermoregulatory ability.