Thank you Chanda and Bevann! I will definitely look into this. Two of my stallions look like absolute crap right now and sand impaction is the only thing that the vet and I can come up with. Bloodwork is normal, teeth were just done this spring (and still look good), fecal egg count was good, but I dewormed anyway because the potbelly-ribby look made me think they had worms. They are on free-choice second cut hay (I rarely feed the second, I usually sell all that we make) but it has been soooo dry this year that the hay has been stemmy. I assumed they needed more protein, so I added a supplement to their feed (16% protein 10% fat broodmare grain). When I did their last purge, these two pooped PURE sand, I mean it looked like you were making meat balls out of beach sand! So I put them on a routine of sand aid for a month, but have seen no improvement. They do not have the telltale runny manure from sand impaction that mine normally get if they miss a purge, but they look dull, pot bellied with hips and ribs out. I am embarrassed for anyone to see them right now! I was thinking that the generic psyllium powder would be cheap enough to be able to dose everybody more for longer. I know that too much/too long prevents nutrient absorption and too much fiber creates that gassy bloated look, but I fear these two need more purging. I know that the Metamucil would not be a better deal for 34 big horses by any means, but I will price it out for the minis once I get an accurate dosing instruction from my vet. It may be like the omneprazole for ulcers, in big horses, tablets are FAR more expensive than ulcergard, but for my 27"mini, the tablets were better because the tube of ulcergard was metered in 600# doses and he weighed 220#. The generic tabs were cheaper. I will find out, thank you.