Effects of pentoxifylline on hemorheologic alterations induced by incremental treadmill exercise in Thoroughbreds

Objectives To determine whether pentoxifylline treatment altered hematologic, rheologic, electrolyte, or blood gas test results of Thoroughbreds during submaximal treadmill exercise. Animals 5 healthy Thoroughbreds that had raced within the past year and had no history of exercise-induced pulmonary hemorrhage. Procedure Mixed venous blood samples were obtained before exercise, at treadmill speeds of 9 and 13 m/s, and 20 minutes after exercise; hematologic, rheologic, electrolyte, and blood gas test results were determined. Results Pentoxifylline treatment resulted in a 45% reduction in RBC filtration pressures for horses at rest. The improved RBC filterability persisted during treadmill exercise. Horses treated with pentoxifylline had a greater decrease in Po2 values and a lesser increase in plasma lactate concentration during treadmill exercise. Conclusion Administration of pentoxifylline improved RBC deformability of horses at rest and during treadmill exercise. Clinical Relevance Improved RBC deformability resulting from pentoxifylline treatment may reduce exercise-associated shear stress in pulmonary capillaries, thereby attenuating exercise-induced pulmonary hemorrhage. (Am J Vet Res 1996;57:1364-1368)