Proin ER is a prescription medicaion for the control of canine urinary incontinence due to urethral sphincter hypotonus. Urethral sphincter hypotonus causes canine urinary incontinence as a result of weakened muscles of the urethral sphincter. Proin ER provides the same proven efficacy as Proin chewable tablets in extended-release tablets for easy once-a-day dosing.