Xylazine-induced hyperglycemia in beef cattle.

Intravenous administration of xylazine to beef cattle (10 animals, 0.2 mg/kg of body weight) resulted in rapid onset (less than 15 minutes) of hyperglycemia. Plasma glucose values increased to 195 +/- 15 mg/dl and 305 +/- 10 mg/dl at 15 minutes and 3 hours, respectively. Concomitantly, plasma insulin concentrations dropped from 23 +/- 2 microU/ml before xylazine to 5.8 +/- 0.7 microU/ml and 2.4 +/- 0.3 microU/ml at 15 minutes and 3 hours, respectively. Parallel decreases (20%) were observed for percentage of hemoglobin, red blood cell number, and packed cell volume. Plasma urea nitrogen was significantly (P less than 0.01) incrased within 3 hours of xylazine administration (6.7 +/- 0.9 mg/dl vs 11.4 +/- 0.7 mg/dl). Marked changes in concentrations of plasma-free fatty acids were not observed. Alternative means of anesthesia must be considered in those instances in which biopsy material is to be used for studies of carbohydrate metabolism in vitro.