Effect of potential therapeutic agents in reducing oxidative stress in pulmonary tissues of recurrent airway obstruction-affected and clinically healthy horses. REASONS FOR PERFORMING STUDY: To determine and compare the reactive oxygen and nitrogen species (ROS and RNS) in pulmonary tissues of horses affected with recurrent airway obstruction (RAO) and clinically healthy horses, and to evaluate the effectiveness of potential therapeutic agents in reducing ROS and RNS in the tissues of these horses