Zolazepam

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 (%SpO 2 ), end-tidal carbon dioxide (ETCO 2 ), 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, %SpO 2 , ETCO 2 , 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.

Due to the limited availability of ketamine in Mexico, alternative anaesthetic protocols for the immobilisation of big cats such as tigers (Panthera tigris ssp.) need to be considered. Therefore, this study aimed to assess the safety and efficacy of an anaesthetic protocol combining tiletamine, zolazepam and xylazine when used in tigers.

Sixteen tigers (seven P. tigris tigris and nine P. tigris altaica) at two zoological institutions in Mexico were included in the study. Tigers were either darted or hand injected with a combination of tiletamine/zolazepam (1.5 mg/kg) and xylazine (0.5 mg/kg). Physiological variables, including heart rate (HR), respiratory rate (RR), body temperature, arterial haemoglobin oxygen saturation (SpO2), systolic blood pressure (SAP), diastolic blood pressure (DAP) and mean arterial pressure, were measured and recorded. The tigers were divided into two groups according to their weight: light (≤40 kg) and heavy (≥100 kg). Wilcoxon rank tests were then used to assess the effects of anaesthesia on HR, RR, SpO2, SAP and DAP.

HR and weight varied significantly among the tigers included in the study, but no statistically significant differences in RR, body temperature, SpO2, SAP or DAP were found. Time to recovery was shorter in tigers that received atipamezole than in those that did not.

The weight, age and sex group sample sizes were unequal. As such, caution should be employed when attempting to draw conclusions from these group comparisons. 

Despite the controversy associated with tiletamine/zolazepam use in tigers, no adverse effects were observed. Therefore, a combination of tiletamine, zolazepam and xylazine is a suitable alternative for tiger anaesthesia when ketamine is not available.