Efficacy and Safety of Sound Wave Treatment of Recurrent Airway Obstruction in Horses

Background: One proposed nonmedical therapy for recurrent airway obstruction (RAO) in horses is a handheld acoustic device that propels sound waves from the nose down the tracheobronchial tree where it is intended to dislodge mucous and relax bronchospasm, permitting clearance of mucoid secretions. Objective: To evaluate the effectiveness and safety of this device when used as per the manufacturer's recommendations as a treatment for RAO. Animals: Nine adult horses previously diagnosed with RAO. Methods: Prospective, cross-over clinical trial. Horses were exposed to a dusty environment until airway obstruction developed as defined by standard lung mechanics (SLM). Horses were randomly assigned to receive either acoustic therapy or a sham treatment for 4 weeks while being maintained in this environment. Horses were evaluated by clinical scores, SLM, and forced expiration regularly for 4 weeks. The opposite treatment was administered after a washout period. Results: Seven horses received the treatment; 9 received the sham. There were no changes (P > .05) in clinical score, maximal change in transpulmonary pressure (Delta P-Lmax), lung resistance (R-L), or the forced expiratory flow rate averaged over the last 75-95% of expiration (FEF75-(95%)) over the study period. The device was determined to be safe, although several minor adverse effects were noted, including head tossing, coughing, and chewing during treatment. Conclusions and Clinical Importance: Treatment with this device did not improve clinical signs or lung function in horses with RAO kept in a dusty environment. Currently accepted treatments, including environmental management and medical therapy, should be recommended.