- Definition
- Pathophysiology
- Systems Affected
- Genetics
- Incidence/Prevalence
- Signalment
- Signs
- Causes
- Risk Factors
BASICS
Gravitational sedimentation of ingested sand in the large intestine causing colonic impaction and mucosal irritation.
Horses ingest sand while grazing on sandy soil or while eating from the ground in sandy stalls or paddocks. Some horses, particularly foals, develop pica and intentionally eat sand or fine grit contained in decomposed granite used for stall or paddock floors. Ingested sand sediments and accumulates in the large colon until impaction and partial or complete obstruction may occur. As the intestinal contents become dehydrated, the sand may dry out and take on a concrete-like consistency. Fine sand tends to accumulate in the ventral colon, whereas coarse sand or grit may also accumulate in the dorsal and transverse colons. Colonic displacement and/or volvulus is found in up to 54% of horses treated surgically for sand accumulation. The amount of accumulated sand required to induce clinical signs is not known and some horses may tolerate more sand than others. Abdominal pain is caused by colonic distention from the impaction or from ingesta and gas accumulating proximally owing to partial or complete obstruction, and by reflex intestinal spasms stimulated by distention. Chronic irritation of the bowel wall and reduction in the absorptive surface area may interfere with normal water absorption in the colon and give rise to diarrhea.
Worldwide, but more common in geographic locations with sandy soil or where horses are kept in sandy paddocks or stalls and fed on the ground.
Feeding hay and/or grain on the ground or grazing on pastures with sandy soil. Recurrent or chronic colic of mild to moderate severity, intermittent or chronic diarrhea, weight loss, and ill-thrift.
Colic, scant or absent feces, although watery to “cow pie” diarrhea, may accompany or precede the onset of colic and may be the major presenting sign. Other signs include anorexia, lethargy, depression, abdominal distention, prolonged capillary refill time, and tachypnea. Auscultation of the colon over the most dependent portion of the abdomen for 1–5 min reveals typical “sand sounds” from sand/sand and mucosal/sand friction. Sand sounds are sensitive and reliable indicators of sand accumulation.
In thin horses with massive accumulations of sand in the colon, external palpation and ballottement of the ventral and ventrolateral abdomen may reveal a firm, heavy viscus. Rectal examination usually reveals distinct distention of the large colon and/or cecum, but definitive diagnosis by rectal palpation is achieved in only about 15% of cases. Fecal sand may be detected as a “gritty” feeling during rectal examination and sand may sediment on the floor of the rectum in horses with concomitant diarrhea.
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS