Platelet function in the racing thoroughbred: implication for exercise-induced pulmonary hemorrhage.

This study investigates platelet function in racehorses, particularly those experiencing exercise-induced pulmonary hemorrhage, finding similarities in platelet behaviour between affected and unaffected horses. The researchers suggest that these findings may indicate a predisposition in horses to clot formation and related vascular issues.

Objective and Grouping of the Study

• The research is aimed at assessing platelet function in thoroughbred racing horses.
• Specifically, the study looks into horses with a condition called exercise-induced pulmonary hemorrhage (EIPH), often referred to as “bleeders”.
• For comparison, a control group of horses without this condition, termed “nonbleeders”, was also examined.

Methods and Findings

• In the study, factors such as platelet aggregation (clumping together of platelets), secretion, and adhesion to rabbit aortic subendothelium (a layer of cells found in rabbit arteries) were considered.
• The findings showed that these factors were similar for both bleeders and nonbleeders.
• Platelets from both groups of horses were observed to readily aggregate or clump together in response to substances like ADP, thrombin, collagen, and arachidonic acid.
• However, the secretion of platelets was seen to occur only with high concentrations of thrombin.

Implication of the Findings

• The study found that platelets in both bleeders and nonbleeders frequently adhered to the rabbit aortic subendothelium.
• In doing so, they tended to form large blood clots (thrombi) rather than single layers or small clusters of platelets.
• These findings suggest that horses, both bleeders and nonbleeders, may have an inherent tendency towards the formation of thrombi and the resultant obstruction in their microvascular system.