Sand Impactions of the Large Colon

Leah C. Gray, DVM, diplomate ACVIM

PRAIRIE EQUINE HOSPITAL, PLLC.
920 West Prairie Ave., Coeur d'Alene, ID 83858.
208-762-0930 * Fax: 208-772-3386

Sand impactions of the large colon are common in horses with access to sandy soils-particularly horses that are fed on the ground. Sand accumulates in the large colon, particularly the right dorsal colon, pelvic flexure, and ventral colon. In addition, sand may trigger diarrhea, presumably as a result of irritation of the colonic mucosa. Furthermore, horses may experience weight loss because of malabsorption (i.e. nutrients are not being absorbed because of interference from the sand.) In horses with sand impactions, clinical signs are similar to those of horses with large colon impactions: dehydration, decreased gastrointestinal motility, depression,anorexia, looking at the flanks, getting up and down. In addition, sand may be found in the feces, and auscultation of the ventral abdomen may reveal sounds of sand moving within the large colon,similar to how the ocean sounds in a seashell. In addition, sand may be detected on abdominal radiography. Radiology of the abdomen has approximately 70% sensitivity when the horse is held off feed for at least 24 hours. A tentative diagnosis is based on clinical signs compatible with a large colon impaction together with evidence of sand in the feces. To determine the presence of sand, several fecal balls are placed in a rectal palpation sleeve or other container, which is subsequently filled with water. If sand is present, it will accumulate in the bottom of thecontainer. If large animal abdominal radiography is available, mineral opacity may be detected within the ventralcolon on radiographs.

Initially, medical therapy is warranted. Administration of Psyllium hydrophilia mucciloid in water by stomach tube may facilitate passage of sand. Mineral oil by stomach tube will allow easier passage of sand without a large degree of colonic irritation from particulate matter. If colic becomes intractable, surgical evacuation of the large colon should be performed. The prognosis is generally good. Prevention for horses living on sandy soil includes daily feeding of psyllium.