Antagonism of Xylazine-Induced Sedation by Tolazoline in the Cat

Abstract

Tolazoline was studied at various doses to examine its effectiveness in antagonizing the xylazineinduced sedation in 45 cats. The cats were given a standard dosage of xylazine (2mg/kg; IM). Tolazoline was given IV at doses of 1 to 5mg/kg or IM at doses of 3 to 7mg/kg which reversed the sedative effects of xylazine. In addition, tolazoline at the above doses reduced or abolished bradycardia and hypothermia induced by xylazine. These effects of tolazoline were dose-dependent. However, tolazoline at a large dosage appeared to cause restlessness, piloerection and hyperemia. In cats given an overdosage of xylazine (5mg/kg; IM), tolazoline at dosages of 5mg/kg (IV) or 10 mg/kg (IM) also antagonized the sedative, bradycardic and hypothermic effects of xylazine.
The results indicated that tolazoline can be clinically used as an effective antagonist to control the duration of xylazine-induced sedation in cats. For this purpose, it is suggested that tolazoline given IV at doses of 1 to 3mg/kg or IM at doses of 3 to 5mg/kg is suitable.