Lasix is just like any other drug used on a regular basis. The body builds a tolerance. When Dr. added Lasix to my list of meds, I would piss every 15 minutes for an hour or so. After 2yrs on it, I piss 3x in 2 hours! I know of a trainer that would give Lasix on his own to all his Lasix horses. With the post time dragging, I think that it probably helps.