Horses ingest sand when they graze meadows with short grass, eat sandy or dusty hay or when they purposely eat sand in the paddock. Eating hay that is provided on the bare ground also increases sand intake. Please note that mud, clay and other types of soil can also cause sand colic. So it’s not only on sandy soils that horses are at risk!
A horse can easily process small amounts of sand. It is excreted with the manure every few days. Most horses have some sand in their bowels, without ever getting into trouble.
Sand builds up in the intestines, especially in the large colon. In case more sand comes in than goes out, it can form a heavy, compact layer on the bottom of the colon. In severe cases of sand compaction over 60% of the intestinal volume can be taken up by sand!
Not only does the sand block the way for food, it also weighs the colon down, which can be painful to the horse. Additionally all this sand will not improve its speed and freedom of motion. In extreme cases almost 100 pounds of sand has been found in one horse! Small stones also regularly show up in the sand compactions. Doesn’t sound very healthy, does it?