Plasma von Willebrand factor in thoroughbreds in response to high-intensity treadmill exercise.

The research focuses in monitoring changes in plasma von Willebrand factor (vWf) level in thoroughbred horses due to high-intensity treadmill exercise. The study found an unexpected decrease in vWf levels post exercise, indicating possible microvascular trauma resulting from rigorous exercise.

Methodology

• The study uses a sample size of five mature thoroughbred horses which are already trained and fit.
• A blood sampling catheter was positioned in the right jugular vein of each horse for easy sampling before, during and after the exercise.
• The exercise consisted of warm-up, a 3-minute rest, and then running at a racing pace until the horse is fatigued, approximately 2 minutes.
• Blood samples were collected at various time intervals: before warm-up, post-warm-up rest period, 1 minute into the run, right after the run, and 5 to 120 minutes post exercise.
• vWf activity in the blood samples was calculated using ELISA and corrected for plasma volume changes, measured by changes in plasma albumin concentration.
• The control group consists of pooled platelet-poor plasma from ten clinically normal resting horses, given a value of 100 U/dl for comparability in the assays.

Results

• There was an observed increase in vWf activity 1 minute after the horses achieved full speed.
• Five minutes post-exercise, the vWf values had increased by an average of 92% from the baseline.
• vWf activity reverted to baseline about 15 minutes after exercise and remained there until 90 minutes post exercise when it began to increase again.

Conclusions

• The researchers concluded that the sudden decline in vWf values following completion of the high-intensity exercise was surprising given the typically long half-life of vWf in circulation.
• The unexpected finding is interpreted to mean there’s likely increased vWf consumption occurring, which implies that microvascular trauma could happen in horses during strenuous exercise.