Evaluation of xylazine, guaifenesin, and ketamine hydrochloride for restraint in horses.

A combination of intramuscular xylazine plus intravenous guaifenesin and ketamine hydrochloride was evaluated as a method for chemical restraint and casting of the adult horse. This drug combination provided safe and rapid induction of the horse and uneventful recovery from lateral recumbency. Cardiopulmonary function remained within base-line values for the adult horse, although cardiac output, arterial blood pressure, and arterial partial pressure of oxygen were decreased from base-line values. Xylazine, guaifenesin, and ketamine hydrochloride provided safe induction to general anesthesia with the inhalation anesthetics halothane or enflurane. Respiratory rate was significantly lower and arterial carbon dioxide higher during maintenance anesthesia with enflurane than with halothane. Recovery from general anesthesia was more rapid after enflurane than after halothane anesthesia.