Blood glucose and insulin concentrations after alpha-2-agonists administration in horses with and without insulin dysregulation.

Abstract

BACKGROUND: In metabolically stable horses, alpha-2-agonists suppress insulin secretion with transient hyperglycemia and rebound hyperinsulinemia. In horses with insulin dysregulation (ID), the effect of alpha-2-agonists has not been investigated; however, both the alpha-2-agonist-induced suppression of insulin secretion and rebound hyperinsulinemia could have clinical relevance. HYPOTHESIS/OBJECTIVES: In horses with ID, alpha-2-agonists will alter insulin and glucose dynamics. ANIMALS: Seven horses with ID and 7 control horses. METHODS: In this randomized crossover study, xylazine hydrochloride (1.1 mg/kg) or detomidine hydrochloride (30&#x2009;&#x3bc;g/kg) were administered IV, and blood was collected for glucose and insulin concentrations at 0, 15, 30, 45, 60, 90, 120, 150, 180, and 300&#x2009;minutes after administration. Horses received each drug in a random order with a 24-hour washout period between drugs. Percent change in glucose and insulin concentrations was compared between groups, drugs, and over time with P&#x2009;<&#x2009;.05 considered significant. RESULTS: A significant time-dependent effect of both alpha-2-agonists on glucose and insulin concentrations in control and ID horses was identified (P = .01 for all comparisons). There was no significant effect of sedative selection and endocrine status on blood glucose concentration in either group; however, in ID horses, xylazine administration resulted in severe rebound hyperinsulinemia whereas detomidine administration did not (P = .02). CONCLUSIONS AND CLINICAL IMPORTANCE: Alpha-2-agonists have a significant effect on glucose and insulin concentrations in horses. In ID horses, detomidine could minimize hyperinsulinemia when compared to xylazine.