Effect of prolonged administration of clenbuterol on airway reactivity and sweating in horses with inflammatory airway disease

Abstract

Objective-To determine whether prolonged administration of clenbuterol results in tachyphylaxis, specifically regarding its bronchoprotective properties and effect on sweating in horses. Animals-8 Thoroughbreds with inflammatory airway disease. Procedures-In a crossover design, horses received clenbuterol (0.8 μg/kg, PO, q 12 h) or placebo for 21 days, with a washout period of ≥ 30 days between the 2 treatments. Airway reactivity was evaluated by use of flowmetric plethysmography and histamine bronchoprovocation before (day 0; baseline) and every 7 days after the start of treatment. Sweat function was evaluated via response to epinephrine administered ID before and every 10 days after the st..