"It does seem sort of counter-intuitive, " said Dr. Proudman, who is also a race course adviser at Aintree.

WSJ: Why They Fear Aintree's First

"If horses haven't been on this course before or been over the practice fences, they won't have encountered a fence that looks quite like this, " said Dr. Proudman.

WSJ: Why They Fear Aintree's First

According to Chris Proudman, a professor of equine studies at the University of Liverpool's Equine Hospital, the first fence is statistically the most hazardous in the entire race.

WSJ: Why They Fear Aintree's First