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 (ΔPLmax), lung resistance (RL), 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.