My 8 yr old percheron x thoroughbred x arabian cross gelding was genetically tested in 08 and is positive for PSSM. His diet is 1 sc Pennfield Omega Fibregized(12.5% fat) 1/3 cup coconut oil 2 x day. His vitamins are Accel Lifetime, Redmond salt, ReitSport HA-100C, E-Sel-Mag. He tied up in Aug following a week off after an intense show season as a adult hunter. He currently has muscle wasting and is very stiff in the hind end.
Is he getting enough fat in his diet and should we add Acetyl L Carnitine to his diet? We know he has problems when the spring grass comes in May due to the sugars in the grass but winter is also problematic. What would you suggest? Thank you.

I recommend 1 pound of fat (2 cups oil) per 1000 pounds of horse per day, and so the first thing will be to increase oil, gradually, to 2 cups per day. The 12.5% fat feed will provide 0.125 pound of fat per pound of feed, so be sure to weigh that scoop of feed. In spring I recommend a grazing muzzle to reduce sugar intake and unwanted weight gain if that is an issue. I heard about the acetyl l carnitine some months ago and actually suggested to a few owners of "easy keeper" horses to try it. So far no one I know of has been impressed with results. It doesn't hurt, though, but fat in the diet is more important. That and as much turnout time and regular exercise as possible.