Changes in coagulation and fibrinolysis in horses during exercise

Area of Science:

• Equine physiology
• Hemostasis and thrombosis
• Exercise physiology

Background:

• Exercise induces physiological changes in horses.
• Hemostatic and fibrinolytic systems are crucial for maintaining blood fluidity and integrity.

Purpose of the Study:

• To investigate the effects of controlled exercise on clotting time (CT) and fibrinolytic activity (FA) in horses.
• To assess changes in plasminogen/plasmin complex activity (PLG), one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), and antithrombin-III (AT-III) during exercise.

Main Methods:

• Six mature female horses underwent two trials (exercise and control) in a randomized crossover design.
• Exercise involved 20 minutes on a treadmill at 2 degrees incline and 5 m/s.
• Blood samples were collected pre-exercise, at 4-minute intervals during exercise, and 15 minutes post-exercise for various coagulation and fibrinolysis assays.

Main Results:

• Clotting time (CT) significantly decreased during exercise (from 21.5 to 9.9 minutes; P<0.05).
• Fibrinolytic activity (FA) and plasminogen/plasmin complex (PLG) levels significantly increased during exercise (P<0.05).
• No significant changes were observed in OSPT, APTT, or AT-III during exercise or in any parameters during control trials.

Conclusions:

• Exercise induces a rapid and significant pro-coagulant shift, indicated by decreased CT.
• Enhanced fibrinolysis during exercise may serve to prevent excessive clot formation.
• These hemostatic and fibrinolytic alterations during exercise are transient and reversible.