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

This study examines how the drug pentoxifylline impacts the blood properties and exercise performance of racing Thoroughbreds. Researchers found that pentoxifylline treatment results in improved red blood cell (RBC) flexibility, potentially reducing the risk of exercise-related bleeding in the lungs.

Studying Effects of Pentoxifylline on Racing Horses

• This research was conducted on five healthy Thoroughbred horses that had a history of racing within the year prior to the study and showed no signs of exercise-induced pulmonary hemorrhage, a condition that causes bleeding in the lungs following strenuous activity.
• The intent of the study was to measure any changes to the horses’ hematologic (blood and blood-forming tissues), rheologic (flow and deformation of matter), electrolyte, or blood gas parameters during submaximal treadmill exercise, both without and with pentoxifylline treatment.

Measurement Methodology

• Testing involved taking mixed venous blood samples from the horses at three distinct stages: before exercise, at treadmill speeds of 9 and 13 m/s, and 20 minutes post-exercise. With these samples, they performed hematologic, rheologic, electrolyte, and blood gas tests.

Results of the Study

• The administration of pentoxifylline resulted in a 45% decrease in red blood cell (RBC) filtration pressures in resting horses, indicating improved RBC flexibility or deformability.
• Importantly, this enhancement in RBC filterability continued even during the treadmill exercise.
• Interestingly, horses treated with pentoxifylline experienced a larger drop in Po2 values (partial pressure of oxygen in blood) and a smaller increase in plasma lactate concentration during the treadmill workout. This could suggest improved oxygen usage and less lactic acid buildup in the muscles, potentially contributing to enhanced performance and recovery.

Conclusion and Implications

• Overall, the research concluded that pentoxifylline treatment enhances RBC deformability in horses, both at rest and during exercise.
• The increased RBC flexibility potentially reduces the shear stress in the horse’s pulmonary capillaries during exertion, which could help in mitigating exercise-induced pulmonary hemorrhage. This has significant implications for the health and performance of racehorses, as it may offer a potential therapeutic strategy to address this widespread issue in the equine racing industry.