Chemomyectomy of the thyroarytenoid muscle is a potential alternative approach to the management of spasmodic dysphonia (laryngeal dystonia) that could provide a prolonged response. To be useful, chemomyectomy should produce weakening of vocal fold closure without disruption of the mucosal wave. Sixteen dogs were studied. In 8 animals, doxorubicin hydrochloride (3 mg) and verapamil hydrochloride (0.5 mg) were injected unilaterally into the thyroarytenoid muscle 2 months before evaluation. The remaining animals served as noninjected controls. Injection of doxorubicin and verapamil decreased the average evoked tension of the vocal fold by 74.7%, compared to an average side-to-side difference of 12.7% in the control group (p = .001). A mucosal wave was recognized bilaterally with videostroboscopy in all dogs. Doxorubicin did not significantly change the vocal fold appearance or mucosal wave amplitude. These results support further laboratory study of chemomyectomy as a potential alternative treatment for laryngeal dystonia.