Propalin Syrup 30 or 100 mls. Prescription required. Used for the treatment of urinary incontinence in dogs caused by urethral sphincter mechanism incompetence. Phenylpropanolamine is a sympathomimetic agent which acts by direct stimulation of the smooth muscle of the internal urethral sphincter. It is indicated in the management of urinary incontinence associated with urethral sphincter incompetence in the bitch.