Investigation of the treatment of sand accumulations in the equine large colon with psyllium and magnesium sulphate

•During 4days of treatment with psyllium and MgSO4, 75% horses underwent resolution of colonic sand accumulation.•Without medical treatment, 20% horses underwent spontaneous resolution of the colon sand accumulation.•Medical treatment was more efficacious than only restricting access to sand.•The capacity of an individual horse to clear the sand accumulation could not be predicted from radiographs. Enteropathy associated with sand accumulation in the large colon of horses has been reported worldwide. Intestinal sand accumulations are commonly treated medically, but randomised controlled clinical trials on horses are scarce. This prospective study evaluated the efficacy of an enterally administered combination of psyllium and magnesium sulphate (MgSO4) for the removal of large colonic sand accumulations in horses without clinical signs of acute colic. The two groups comprised 20 untreated control horses and 20 horses treated with 1g/kg bodyweight (bwt) of psyllium and 1g/kg bwt of MgSO4 administered by nasogastric intubation once daily for 4 days. Both groups had no access to soil during the study period. The amounts of accumulated sand were evaluated radiographically before and after treatment. Significantly more treated horses cleared their sand accumulations than horses in the control group. This clearance was determined by observing the estimated quantity by area of sand remaining in the large colon (P