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

Objectives-To determine whether pentoxifylline treatment altered hematologic, theologic, 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 P-O2,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.