Telazol® is the drug of choice for immobilization of polar bears. It can be delivered in a relatively small drug volume and will produce safe, reliable immobilization. Recoveries from Telazol® may be prolonged and a “reversible” combination may be desirable in some situations. Medetomidine-Telazol® can be delivered in a low volume and will produce reliable immobilization of polar bears. The following study was performed to determine cardiopulmonary effects of medetomidine-Telazol® and Telazol.® Six captive polar bears, with an average weight of 122 ± 22 kg, were used in this study. The bears were fasting during the time of the study, and had access to fresh water. Treatments consisted of 74.8 ± 11.8 ug/kg of medetomidine + 2.2 ± 0.3 mg/kg of Telazol® (MZT) or 8.2 ± 2 mg/kg of Telazol® (TZ). All reported values are mean ± SD. Each bear received both treatments, administered IM with a pole syringe, at least 5 days apart. Bears were placed in dorsal recumbency and a 20 gauge, 5 cm catheter was placed in the femoral artery for measurement of direct arterial pressure. Arterial samples were withdrawn at 15 minute intervals for blood gas analysis. HR, RR, BP, and temperature were recorded at 5 minute intervals. Lead II ECG was monitored continuously. At 60 minutes post-injection (PI) medetomidine was antagonized with atipamezole at 3 times the medetomidine dose. Repeated measures ANOVA was used to compare between treatments. One way ANOVA for repeated measures was used to compare differences over time within treatment groups. A Bonferroni test was used for comparison at specific time points when significant differences (P < 0.05) were noted. Immobilization occurred in 3.7 ± 1 minutes following TZ and in 3.7 ± 2.7 minutes following MZT. HR, RR, PaO2, and BE were significantly lower and systolic, mean and diastolic BP were significantly higher with MZT compared to TZ. Hypertension was present with MZT with mean arterial pressure of 237 ± 32 mmHg observed at 15 minutes PI. BP did not change significantly over time. Hypoxemia was present with MZT early in the immobilization period. At 15 minutes PI PaO2 was 53 ± 9 mmHg. PaO2 increased significantly over time to peak at 78 ± 9 mmHg at 60 minutes PI. PaCO2 (44 ± 9 mmHg at 15 minutes PI) was close to normal values for other species. PaCO2 did not change over time suggesting that hypoxemia with MZT was probably a result of ventilation-perfusion mismatch. Oxygenation was adequate with TZ, with the lowest value, 80 ± 15 mmHg, at 15 minutes PI. Hypertension and hypoxemia could cause complications in bears with cardiopulmonary compromise. Supplemental oxygen should be administered to bears receiving MZT.
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