Tiletamine-Zolazepam for Total Intravenous Anesthesia in Sheep

Total intravenous anesthesia (TIVA) is an alternative to inhalant anesthesia when inhalant anesthesia is unavailable or contraindicated. This study investigated the anesthetic efficacy of tiletamine-zolazepam (TZ) through continuous rate infusion in sheep undergoing a 120-minute noninvasive imaging procedure. We hypothesized that the TZ continuous rate infusion would provide effective general anesthesia for imaging. Six male Dorset sheep were sedated with 4-6 mg/kg TZ intramuscularly, intubated, and maintained on 5-15 mg/kg/h TZ intravenous continuous rate infusion. Measured anesthetic parameters included heart rate, oxygen saturation (%SpO2), end-tidal carbon dioxide (ETCO2), body temperature, and direct arterial blood pressure (systolic, diastolic, and mean); blood gas analysis was performed during anesthesia. Time to extubation and standing (recovery) were measured. Other clinical observations (thrashing, activity, vocalization, and general appearance) were also assessed throughout recovery. Heart rate, %SpO2, ETCO2, body temperature, and direct arterial blood pressure were stable throughout imaging anesthesia. Time to extubation and standing (recovery) were 25 ± 6.5 and 34 ± 8.0 minutes, respectively. No abnormal clinical observations were noted. These data suggest that TZ TIVA provides effective general anesthesia for up to 120 minutes of noninvasive imaging.