A horse’s intestinal tract is about 100 feet long. Sand colic and impactions most commonly occur in areas where horses graze on sandy soil pastures or eat off ground that is predominantly sand or fine gravel. Sand moves through the digestive tract with food and is passed in manure, but it also can irritate the intestinal lining along the way. This irritation can lead tounexplained diarrhea episodes, weight loss, and colic. If sand accumulates, it weighs down the intestine and can impair motility, hindering proper digestion and function. Reduction in motility hinders passage of sand and leads to more accumulation, and in some cases the slowdown and accumulation cause a blockage.
A simple way to test for sand is to use a clear glove. Pick up a fecal sample (about 3 balls) with it turned inside out,then turn it so it contains the sample. Pour water into the glove, and mash the water together with the feces. After you shake it and let everything settle, the sand (being heavier than manure) will gravitate down into the fingers of the glove.
If you see any sand at all, you should treat your horse. You can use a commercial sand remover for horses. These contain psyllium and are easy to find at your local feed store. Try to limit sand ingestion by not feeding your horses on the ground. You can place rubber mats in about an 8 x 8 square if you must hay on the ground in sandy areas.