Sand accumulation in the gastrointestinal (GI) tract of horses occurs commonly in regions with sandy soils, including Arizona, California, Florida, New Mexico, and Texas. Affected horses consume the sand inadvertently while grazing or eating off the ground. Horses housed on drylots with sand or dirt as the footing are more predisposed to picking up and ingesting sand as they eat, particularly if they are fed off the ground. Other predisposing factors can include poor-quality feed, overgrazed or overstocked pastures, and hierarchy if horses are housed together. Because sand weighs more and is finer than feed, it tends to settle and accumulate in a layer on the bottom of the large colon. A significant amount of sand can build up in the gut over time, leading to obstructions and irritation of the GI tract lining and resulting signs of colic (abdominal pain), weight loss, and diarrhea.

Diagnosing Sand Colic

If a horse exhibits signs of colic, and the owner or veterinarian believes sand might be a contributing factor, certain diagnostics can help confirm their suspicions. In addition to the routine colic diagnostic work-up, careful auscultation (listening with a stethoscope) of the ventral (lower) abdomen might reveal oceanlike sounds indicating the presence of sand. Veterinarians can also measure fecal sedimentation by placing fecal balls in a rectal sleeve and adding water to see if sand accumulates in the fingers of the glove. However, these methods are not always accurate, and horses with significant sand accumulations might not have sand in their feces at the time of examination. An ultrasound exam can help identify the presence of sand, but it can be subjective and does not help the vet quantify how much sand is present.

Gastrointestinal tract radiographs allow veterinarians to definitively identify sand in the gut and quantify how much has accumulated. The downside is this diagnostic modality might only be available in a hospital setting and not in the field, particularly for larger horses. Abdominal radiography is the best diagnostic method for evaluating the amount of sand accumulation, and it can also serve as a tool for monitoring sand disappearance with treatment. Further, evaluating radiographs for excessive gas accumulation might increase the index of suspicion of a displacement or complete obstruction in painful horses and expedite going to surgery if colic signs persist despite medical treatment.

Treating Sand Colic

Medical treatment of sand impaction is similar to that of other colic types and includes rehydration by intravenous (IV) or enteral methods and giving laxatives. Enteral fluids are administered via nasogastric tube passed through the nasal passages to the esophagus and stomach. This allows administration of a large quantity of water (up to 7-8 liters in an average 1,100-pound horse) and electrolytes and supplies the GI tract directly. Laxatives, such as magnesium sulfate (Epsom salts) can also be administered to help break up possible impactions. Mineral oil is usually not as effective, as it tends to pass around the sand. Veterinarians usually administer psyllium to help evacuate the sand, but not until the horse is passing formed manure and any possible obstruction has resolved.

If colic signs continue to progress despite medical therapy, surgical intervention to remove the sand and resolve the obstruction or displacement might be necessary.

Prognosis for medical and surgical management of sand colic is good, and most horses respond well to treatment. The most severe complication associated with sand colic is rupture of a portion of the GI tract due to complete obstruction and damage to the bowel wall.

Preventing Sand Colic

The most important factors in preventing sand colic are management and reducing horses’ access to sand. If restricting sand access is not possible, then ensure horses are not fed on the ground. Tubs, haynets, and feeders can help reduce their potential for ingesting sand with food. Laying down rubber mats to catch dropped hay or grain can further reduce sand ingestion. Remember to clean the mats and tubs regularly, because sand-filled feeders and mats defeat the purpose of their use. Good-quality feed is also important. Feeding psyllium pellets one week a month can help keep sand passing through the GI tract rather than accumulating in it. However, this should be done in addition to and not in lieu of these management strategies.