My horse has been on Orchard Grass for the last several years. His turnout is on a dry lot with no pasture grass.

He now has the opportunity for turnout on pasture grass. Is the sugar content in the pasture grass too high for an EPSM horse?

I think the only way you'll know is to try it. Just use common sense, of course--start him slowly, maybe a half hour at first and slowly increase the time, and see if he gets stiff or sore. Early morning and nighttime are safest, sugars increase as the day wears on and the grass stores it up to live on overnight, so avoid afternoons if you can. Get him a grazing muzzle to slow down his intake if you have to--they have inexpensive ones at Valley Vet Supply that are as good as the expensive Best Friends model.

Some EPSM horses are sensitive to pasture grass and others do not seem to be. They do need to be on the right amount of fat to help counterbalance the starch and sugar in grass. My best advice is to give this a try, keep close watch on your horse, and if there is any indication of EPSM issues arising try a grazing muzzle. The starch and sugar content of grass varies quite a bit. Lush spring grass seems to lead to more sugar intake, but stressed grass will also have sugars. Grass has so many other good things for a horse, including vitamin E, that I really like to try to give them pasture when at all possible.