Effect of Succinylcholine Chloride on the Cardiac Function of the Horse

Abstract

Investigation was carried out to determine the effect of succinylcholine chloride on the cardiac function of the horse, using 12 healthy horses, which were divided into five groups according to dosage. The five groups, 1 to 5, were injected intravenously with succinylcholine chloride at a dose of 0. 05, 0.10, 0.17, 0.30 and 0.17 mg/kg after premedication with atropine sulfate. Electrocardiograms were continually taken by a radio-telemeter over a period after the injection of the drug to the recovery. The results obtained were as follows : 1. Six to 35 seconds after the injection the horses fell down. This interval of time tended to shorten in accordance with the increase of dosage. In group 1, two of the five horses failed to fall down after the injection. The casting state lasted 1 minutes and 56 seconds to 28 minutes and 31 seconds after the injection. The length of this period tended to prolong in accordance with the increase of dosage. 2. Two horses of group 1 and all the horses of groups 2, 3, and 4 showed complicat ed arrhythmias 17 to 52 seconds after the injection. These arrhythmias continued for 46 seconds to 6 minutes and 45 seconds. The length of this period tended to prolong in accordance with the increase of dosage. 3. The electrocardiograms of the horses involved in arrhythmias revealed atrioventricular block, escaped beats, extrasystoles, paroxysmal ventricular tachycardia, and short runs of ventricular flutter. There was a tendency for ventricular flutter to increase in occurrence with an increase in dosage. In group 5, which had been premedicated with atropine sulfate, all horses failed to show arrhythmia. 4. After the disappearance of arrhythmia, almost all horses revealed sinus tachycardia, or 126234 per minute. This phenomenon was observed, regardless of the dosage.