Effect of a competitive inhibitor of platelet aggregation on experimentally induced laminitis in ponies

OBJECTIVES: To determining whether inhibition of platelet aggregation prevents development of carbohydrate overload-induced alimentary laminitis. ANIMALS: 22 healthy adult ponies. PROCEDURES: Acute laminitis was induced by oral administration of corn starch/wood flour to 16 ponies, 8 of which were treated with a synthetic analogue of the platelet fibrinogen receptor antagonist peptide (RPR) RGDS (arginine-glycine-aspartic acid-serine) 110885; 6 ponies served as negative controls. Blood was collected before and at 4, 8, 12, 24, 28, and 32 hours after administration of carbohydrate overload, and PCV, total plasma protein concentration, platelet count, activated clotting time, whole blood recalcification time, spontaneous platelet aggregation, ex vivo platelet aggregation responses, in vivo platelet activation, and platelet-neutrophil aggregates were evaluated. RESULTS: Of 16 ponies given carbohydrate, 6 of 8 untreated ponies developed laminitis and 0 of 8 ponies treated with RPR 110885 developed laminitis. The RPR 110885 treatment attenuated the increase in platelet-neutrophil aggregates observed in untreated ponies. CONCLUSIONS: Platelets are involved in the pathogenesis of equine alimentary laminitis. CLINICAL RELEVANCE: Platelet aggregation inhibitors may be useful for prevention or treatment of laminitis, or both.