A necropsy revealed that an acute aortic rupture caused Hickstead’s death on November 6th. While this will end speculation, it still leaves questions because very little is known about what causes aortic ruptures.

An article in The Horse, quotes Janice Bright, DVM, Dipl. ACVIM (Specialty of Cardiology), associate professor of cardiology, Colorado State University who explains:

Aortic ruptures usually occur very close to the junction of the aorta with the heart. This may result in acute hemorrhage into the pericardial sac. Because there is such a large volume of blood that flows under very high pressure within the aorta, aortic ruptures close to the heart often result in very serious clinical consequences, including sudden collapse and sudden death.

Why it happens is far less understood. Some vets believe that a congenital aneurysm might be the cause; others believe that there is a gradual weakening caused by a degenerative disease. Another theory is that migrating parasites, such as strongyles, could weaken a horse’s heart which could cause structural weakness to the wall. Or that a deficiency in copper — copper is needed to make strong bond between elastin and collagen in blood vessel walls.

According to Eric Lamaze, Hickstead felt fine during the competition, even during his last jumping efforts. Right up until the moment when he collapsed. It could not have been prevented and there is nothing that could have been done to save him. I know that when Kroni died, I took a small amount of comfort from the fact that there was nothing I could have done to prevent it. I hope that Hickstead’s connections are able to find some comfort, too, knowing that it was beyond their control.