Application of the 51Cr-EDTA urinary recovery test for assessment of intestinal permeability in the horse

Altered intestinal permeability is implicated in the pathogenesis of diverse equine medical conditions including alimentary laminitis and protein-losing enteropathies associated with parasitic infection. The aims of this study were to assess the feasibility of applying the 51Cr-EDTA absorption test for the assessment of intestinal permeability in the horse, and to apply this test in horses with experimentally induced alterations in gastrointestinal function. Four healthy ponies were administered 36 MBq of 51Cr-EDTA via naso-gastric tube, and urine samples were collected into polythene bags strapped to the pony's abdomen. Total urine voided every 6 h was collected during each test, and 1 ml samples were taken for measurement of gamma-radiation. Urinary recovery of 51Cr-EDTA was measured following intravenous atropine sulphate or bethanecol, and following 22 and 46 days of administration of 250,000 third-stage cyathostome larvae. There was no significant difference in urinary 51Cr-EDTA recovery following the control treatment, and following atropine or bethanecol administration, but significant increases were detected in the animals with experimental cyathostome infection consistent with increased permeability of the intestinal membrane. Motility modifying agents (bethanecol and atropine) did not affect absorption of 51Cr-EDTA, suggesting that subtle changes in motility might not affect the ability of this test to detect altered intestinal permeability. The finding of increased urinary recovery of 51Cr-EDTA in ponies with cyathostome infection suggests that 51Cr-EDTA may be a useful marker for assessment of intestinal permeability in the horse.