Sand Rid Sand colic is one of the most preventable diseases known. Horses in sandy areas or that are turned out in sand rings and spend a lot of time eating feed off the ground are prone to ingest some sand. Sand is not digestible so the more sand that builds up in the horses intestine the more prone they are to sand colic. Some but not all sand is always passed thru the intestine so feeding a Psyllium based supplement is key to preventing Sand Colic.