I know this sounds stupid but is there such a thing as a diet supplement for horses? I know a mare who is 200 lbs over weight from being left at pasture with no exercise. She is currently only getting 2 flakes of hay a day, once in the morning and once at night, and is currently being exercised everyday (idk if every day will continue though, I am working with her for a parade this weekend but I can't afford to go out every day all the time, it will go back to 2-3 times a week next week). I know there is feed supplement to help a horse gain weight, is there anything to help them lose it?
Worse quality hay and a multi-vitamin. Limited grazing ( grazing muzzle).
More exercise.
Http://www.horses-and-horse-information.com/horsenutrition.shtml
and work her harder!