The best way to deal with a scouring problem is to gain an understanding of the particular factors which predisposed your particular horse to the problem in the first place.
This varies in each case and the tendency of one horse to continue with this metabolic habit of rushing things through long after the initial cause has passed and another not to is a function of the difference in their individual nervous systems.
I would recommend the slippery elm powder mixed into some cool chamomile tea, see the following link: