Transient alteration in intestinal permeability to technetium Tc99m diethylenetriaminopentaacetate during the prodromal stages of alimentary laminitis in ponies

Objectives - To determine whether mucosal permeability is altered during the prodromal stages of alimentary laminitis. Animals - 15 healthy adult ponies. Procedures - Intestinal permeability was evaluated for control ponies (n = 5) and for ponies 4 to 12 (n = 5) and 20 to 28 (n = 5) hours after administration of carbohydrate overload. Mucosal permeability was determined by measuring the percentage of orally administered technetium Tc99m diethylenetriaminopentaacetate ((99m)Tc-DTPA) excreted in urine during an 8- hour period, then measuring blood radioactivity at hourly intervals. Plasma endotoxin-like activity was measured by use of a chromogenic Limulus amebocyte assay. Results - Urinary excretion of (99m)Tc-DTPA was 2.45% of administered dose for control ponies, and was 16.67% of administered dose 4 to 12 hours and 3.57% of administered dose 20 to 28 hours after administration of carbohydrate. Conclusions - A marked but transient increase in intestinal permeability was observed early in the prodromal stages of alimentary laminitis. Clinical Relevance - Absorption of substances from the intestine may be an initiating event in alimentary laminitis.