Oxidant‐Antioxidant Status in the Blood of Horses with Symptomatic Recurrent Airway Obstruction (RAO)

BACKGROUND Systemic oxidative stress in horses with recurrent airway obstruction (RAO) is poorly characterized. OBJECTIVES The goal of this study was to investigate whether equine RAO is associated with systemic disturbances in the oxidant-antioxidant equilibrium. ANIMALS Seven healthy horses and 7 horses with symptomatic RAO. METHODS A prospective study. Healthy and RAO-affected horses were exposed to a 48-hour challenge with moldy hay and straw to induce clinical exacerbation of RAO. Venous blood was collected and the activities of the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) in equine erythrocyte lysates were measured. The concentration of thiobarbituric acid-reactive substances (TBARSs) was assessed both in erythrocyte lysates and in plasma. RESULTS A significant increase in the activities of GPx and SOD was detected in RAO-affected horses compared with the control animals. There was no significant difference between groups in terms of the erythrocyte lysate activities of CAT, GR, or TBARs or the plasma concentration of TBARs. CONCLUSION AND CLINICAL IMPORTANCE Our results support the hypothesis that RAO in horses is associated with systemic oxidative stress. Future studies are needed to assess whether horses suffering from RAO can benefit from antioxidant supplementation.