[The antagonism of ketamine/xylazine anesthesia ("Hellabrunn mixture") in wild zoo ruminants].

The ability of the antagonists tolazoline, yohimbine and the combination of yohimbine with 4-aminopyridine to reverse the effects of the xylazine-component of the "Hellabrunn mixture" (125 mg/ml xylazine and 100 mg/ml ketamine) on nondomestic zoo ruminants is discussed. Arousal time, recovery time and changes in the parameter of circulatory and respiratory functions after antagonization are shown. Tolazoline is able to antagonize the xylazine effect completely within a short time. Using a dosage of 3-5 mg/kg there is a marked negative effect on the cardio-vascular system. Yohimbine in the used dosage of 0.25-0.3 mg/kg in non-domestic ruminants did not approve in its effects. Combining yohimbine (0.25-0.3 mg) with 4-aminopyridine (0.5 mg/kg) recovery time is about 30 minutes. The negative effect on the cardio-vascular system is less pronounced compared with tolazoline.