The cardiovascular and respiratory parameters of eight laboratory beagles were measured before and after the simultaneous injection of medetomidine (40 micrograms/kg bw) and ketamine (5 mg/bg bw). This combination produced a significant alteration in cardiovascular function. The heart rate, the stroke volume and cardiac output decreased while the systemic vascular resistance increased. These effects were attributed principally to the alpha 2 agonist compound combined with the moderate stimulatory effect of ketamine. The respiratory parameters were little affected by this protocol.