ABSTRACT
To determine the antagonistic effects of tolazoline on xylazine Hcl sedation, 12 male Holstein calves of 8 to 12 months age with an average weight of 210 Kg were considered and arranged in 2 groups of 6 calves as the test and control groups. All calves were received an initial IM injection of xylazine Hcl [0.4 mg/Kg of 2% solution] followed in 15 minutes by IV injection of Tolazoline [2 mg/Kg of 10% solution] in test group and IV injection of the same volume of 0.9% normal saline in control calves. The significance reversal effects of tolazoline for xylazine Hcl on rectal temperature, heart and respiratory rates and recovery time [9.67 +/- 0.7 minutes] [P<0.05] indicated that, tolazoline is potentially enable to diminish the undesirable effects of xylazine Hcl such as prolonged sternal recumbancy with minimal complications