Cardiorespiratory Effects of the Intravenous Administration of Tiletamine‐Zolazepam to Dogs

The anesthetic, hemodynamic, and respiratory effects of an intravenously administered 1:1 combination of tiletamine and zolazepam were evaluated in dogs. Each dog received tiletamine‐zolazepam (6.6, 13.2, 19.8 mg/kg) on two occasions, once when awake and a second time with residual isoflurane anesthesia while instrumented for the recording of hemodynamic data. Tiletamine‐zolazepam administered to conscious dogs resulted in good, rapid induction of anesthesia. Time to sternal recumbency (recovery) was dose‐dependent. Character of recovery tended to be better with the lower dose. Tiletamine‐zolazepam caused significant increases in heart rate after all doses and significant increases in cardiac output after the two larger doses. All doses caused significant decreases in arterial blood pressure at 1 minute. Arterial blood pressures returned to baseline and then increased significantly above baseline values. The rate of development of left ventricular pressure was significantly decreased 1 minute after the two higher doses, returned to normal, and then was significantly increased above baseline for all doses. Peripheral vascular resistance increased transiently 1 minute after the 6.6 mg/kg dose. Peripheral vascular resistance decreased significantly after the 13.2 and 19.8 mg/kg doses. Minute ventilation was significantly decreased only after the 19.8 mg/kg dose.