Sand Colic in Horses and Ponies

 

Rachel Gardner, DVM, DACVIM

Internal Medicine Specialist, B.W. Furlong & Associates

The accumulation of sand in the intestinal tract of the horse can cause a variety of clinical signs. Sand impactions are common in horses and ponies with access to sandy soils, especially if they are fed supplemental grain or hay from the ground. Horses appear to have significant individual variation as to how much sand accumulates in the intestinal tract vs. being passed through with the manure. Sand most commonly accumulates in the dorsal or ventral portions of the large colon. The most frequent signs associated with sand accumulation are mild colic or diarrhea due to the weight and irritant nature of the sand in the large colon. Signs of mild colic due to sand accumulation may include stretching out, decreased appetite, and increased recumbency (laying down more than usual). More severe signs of colic may be observed when the sand results in a complete obstruction of the large colon, or if the colon displaces (twisting or the colon such that it no longer lies in the correct anatomical position in the abdomen) secondary to the weight of the sand.

Diagnosis of colic due to sand accumulation can be difficult. Knowledge that the horse lives or grazes on sandy soils may be helpful in achieving a diagnosis. Auscultation of the abdomen occasionally reveals the sound of sand moving in the ventral colon. Fecal material mixed with water may result in sand settling to the bottom of the container. Trans-rectal palpation may reveal evidence of large colon distension, but the sand itself is rarely palpated. Peritoneal fluid, the fluid that bathes the intestinal tract within the abdomen, typically remains normal except in severe of long-standing cases. Radiographic evaluation of the abdomen, especially useful in small horses, ponies or foals, tends to be the most helpful diagnostic test and may reveal a mineral opacity in the colon suggestive of sand accumulation.

In horses with mild signs of colic, medical treatment is attempted. Psyllium hydrophilic mucilloid, mixed with water and/or mineral oil, is typically administered directly into the horse’s stomach by the use of a nasogastric tube. The psyllium forms a gel within the horse’s intestinal tract that is believed to stimulate intestinal motility and mixing of the intestinal contents, thereby promoting sand evacuation. Alternatively, the psyllium may physically adhere to the sand such that the sand is passed in the feces with the psyllium. Repeated doses of psyllium are typically required and the treatment appears to have variable success in the elimination of sand. Even when medical treatment is successful at removing the impaction, complete recovery may be prolonged due to chronic irritation from residual sand.

If signs of pain progress or are difficult to control, or if a horse begins to appear systemically compromised, surgical intervention may be necessary. When a horse undergoes surgical correction of a sand impaction, the large intestine is typically manually evacuated of the sand via a small incision into the intestinal wall while the horse is under general anesthesia. Potential complications include contamination of the abdomen from the intestinal contents and rupture of the intestinal wall due to loss of integrity from irritation.

Treatment for sand colic can be difficult and expensive. Thus, taking preventive measures to prevent sand colic are important. Keeping horses off of sandy soils and avoiding turnout in sandy areas, such as arenas, is most desirable. When sandy soils cannot be avoided, reduction in sand ingestion is best achieved by feeding out of bunks or out of buckets. In addition to its role in the treatment of sand colic, psyllium has also been used as an aid in prevention of sand accumulation. Although the effectiveness of this practice has been questioned, psyllium may help to promote evacuation of sand and appears to be beneficial to the health of the colon. Psyllium may be obtained in powders or pelleted forms in various different flavors. Caution must be exercised with the powder form, however, as it may congeal and form an obstruction in the esophagus when used orally in large doses.

Despite taking measures to decrease the ingestion of sand, horses may still develop signs of colic from sand accumulation. When diarrhea or colic are observed in a horse, especially if grazing on sandy soils, it is important to have a veterinary evaluation in order to achieve a proper diagnosis and pursue timely, appropriate therapy.

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