"When There Was no Salt, we Ate Sand”

by R. Paul Schwab, DVM

Have you ever had one of those horses that just wasn’t right no matter what you treated it for? Even if it had good teeth, no parasites, and ate good feed and hay? Sand ingestion could be the culprit.

Horses may unintentionally ingest sand when grazing on loose sandy soils or if they are fed hay on the ground in sandy stalls or paddocks. Horses that are not getting enough forage because of overgrazed or overcrowded pastures are particularly at risk of sand ingestion. Young horses tend to be more curious and may eat sand as well.

Over time, sand accumulates in the large intestine. Gravity and the weight of the sand prevent it from passing completely through. The sand is very irritating to the lining of the intestine and reduces the amount of fluid and nutrients the intestine can absorb. Eventually this leads to diarrhea, and the horse can show signs of colic from intestinal irritation and spasms. With large amounts of sand, the large intestine can become impacted or blocked, often requiring surgical intervention.

Clinical signs of sand accumulation in the intestine include loose manure, ill-thrift (similar to the "ADR" mentioned in last month's article), mild to severe colic, lethargy, dehydration, and possibly sand in the manure. Often you can hear the sand in the intestine when listening under the belly with a stethoscope (sounds like the beach).

Colic from sand ingestion is treated with pain relief, large amounts of oral or intravenous fluids and electrolytes, mineral oil and psyllium. Psyllium is a bulk laxative fiber supplement (basically Metamucil) that is thought to suspend the sand granules and make it easier for the horse to clear the sand. In refractory cases that do not respond to this treatment, surgery is needed to remove the sand from the large intestine. I’ve heard of equine surgeons removing several trash cans worth of sand from the intestines of some horses. Radiographs are sometimes taken to make a diagnosis or double-check removal of the sand after treatment.

Diagnosis of sand ingestion can be made by clinical signs, history, and testing the manure. Sometimes you can see the sand in the manure if there is quite a bit. An easy way to test the manure is by placing 3-5 fecal balls in a rectal examination sleeve and mixing them with water to make a watery slurry. Hang the open end on the fence and let it settle for several minutes. If there is sand in the manure, it will settle into the fingertips. Unfortunately, this test isn’t always accurate. Horses can have sand in the intestine but not always in the manure.
Testing manure for sand

Prevention of sand colic is centered on preventing ingestion. Feed good quality and quantity of forage (hay and pasture) and use hay bags or racks when possible. Also feed grains in grain tubs or buckets. Salt and trace minerals should always be available to horses. Horses without salt or minerals will look for them in the dirt or sand.

Finally, there are several brands of psyllium supplements available commercially that can be fed as a preventative measure and/or treatment for horses that live in sandy areas. Talk to your veterinarian if you think your horse may be at risk for sand colic.