Question: I believe my 22 yr old QH mare has PSSM. Rather than subjecting her to a test, I am going to put her on the suggested PSSM diet. I am currently feeding 2 lbs. Triple Crown Senior, 1 lb Triple Crown 30% ration balancer, and 2 oz Cool Stance Turmericle. I was planning on upping the fat content with ground flax. What kind of supplements should I feed i.e. alcar, vitamin E? The symptoms she exhibits are shifting lameness, dragging of hind feet, sensitive skin, tight muscles (shoulder and hind quarters) reluctance to work and a general depressed air. I have had her lameness rested and it is not her hooves. She also has had a shot of OsPhos. Dr. Kellon: She could have PSSM, but those symptoms are very vague and could also be musculoskeletal/lameness  (which is why she received OsPhos) or even Lyme disease or neurological. She should at least be checked for Cushing's (PPID) because of her age.
As for PSSM diet, the senior feed and balancing have too much starch/sugar. Switch to Equi-Base Senior and feed her a mixture of beet pulp and up to 1 lb of Flax. If you want to go high fat, add 4 to 6 oz of CocoSoya. Vitamin E dose should be at least 2 tsp of Uckele Liquid E. If adding extra fat feed 1 gram L-carnitine per 100 lbs of weight. If not adding more fat, use the same dose but acetyl-l-carnitine.