ANTAGONISM OF XYLAZINE SEDATION BY 4-AMINOPYRIDINE AND YOHIMBINE IN CATTLE

  • 1 January 1982
    • journal article
    • research article
    • Vol. 43  (12) , 2165-2169
Abstract
Crossbred steers (4 groups of 6 steers each) were injected i.m. with a standard dosage range of xylazine hydrochloride (0.2-0.3 mg/kg body wt). When the steers were maximally sedated, group I (control group) was given isotonic saline solution (1 ml, i.v.), group II was given 4-aminopyridine (4-AP, 0.3 mg/kg) i.v., group III was given yohimbine hydrochoride (0.125 mg/kg) i.v. and group IV was given 4-AP (0.3 mg/kg) plus yohimbine hydrochloride (0.125 mg/kg) i.v. The 4-AP decreased mean standing time (MST; time until animal could stand unaided) from 94.3 (control) to 13.4 min. Yohimbine decreased MST to 27 min. The combination of 4-AP + yohimbine decreased MST to 7.4 min. Mean total recovery time (MTRT; time from xylazine injection until normal behavior, including eating and drinking) was not significantly (P > 0.05) decreased from control values by any of the antagonists tested. The combination of 4-AP + yohimbine decreased MST in animals given a 3.times. overdose of xylazine (0.6 mg/kg) from 124 min (control) to 30.3 min. The MTRT was not significantly (P < 0.05) decreased from control values. Two animals given a 5.times. overdose of xylazine (1 mg/kg) and then given 4-AP + yohimbine had a MST of 32.5 min and a MTRT of 3.7 h. The combination of 4-AP + yohimbine produced marked antagonism of xylazine sedation in cattle. The combination of antagonists may prove to be useful for the arousal of animals sedated with xylazine alone or with a combination of sedatives including xylazine.