The effects of diazepam or lidocaine on the propofol induction dose and certain cardiovascular parameters were documented in this randomized, blinded study. Dogs received 0.9% saline (0.1 mL/kg intravenously [IV]), lidocaine (2 mg/kg IV), or diazepam (0.25 mg/kg IV) prior to propofol IV until loss of jaw tone was achieved (up to a maximum of 8 mg/kg). Propofol was followed by 0.3 mg/kg atracurium IV. Direct arterial blood pressures and heart rates were recorded before premedication, induction, and intubation. No statistically significant differences were found among the groups for cardiovascular measurements or for the propofol dose required for intubation.