Clinical experience with hydralazine for treatment of otherwise intractable cough in dogs with apparent left-side heart failure.

Eleven dogs with mitral regurgitation and severe cough were given hydralazine for reduction of systemic arterial pressure. The treatment was stopped and then restarted. Heart rates were measured and cough was assessed subjectively by the clients during each period. While the dogs were receiving hydralazine, heart rate and severity of cough decreased, when compared with periods either before or between treatments. Clinical improvement may have resulted from increased cardiac output or reduction in regurgitation. The improvement also may have resulted from effect on pulmonary function inasmuch as we had no evidence that the signs were a result of heart disease.