Effect of yohimbine on xylazine-induced central nervous system depression in dogs.

Yohimbine was studied at various dosages to examine its effectiveness in reversing as well as preventing xylazine-induced CNS depression. Intravenous injection of xylazine (1 to 10 mg/kg) induced a dose-dependent CNS depression that was prevented by a low dosage of yohimbine (0.1 mg/kg, IV). Xylazine at a dosage of 10 mg/kg induced convulsions in 3 of 5 dogs. In addition, the CNS depressant effect of xylazine (1 to 10 mg/kg, IV) was reversed by yohimbine at dosages ranging from 0.01 to 1.0 mg/kg. Yohimbine alone at dosages of greater than or equal to 0.33 mg/kg appeared to cause apprehension for 20 to 60 minutes. The results indicated that yohimbine can be used as an antagonist to control the duration and depth of xylazine-induced CNS depression. For this purpose, it seemed that yohimbine at a dosage of 0.1 mg/kg is suitable.