Almost nothing in sports is as dreaded as the death of a horse. Every time a stallion or thoroughbred falters in a competition, breath is held and terrifying memories come to mind.

On Sunday, the worst came to pass. Hickstead, one of the world's most beloved horses, collapsed at a show-jumping tournament in Italy.

Hickstead was a superhorse, carrying Canadian show-jumper Eric Lamaze to equestrian gold in the 2008 Olympic Games. He was 15 years old and still at the top of his game, completing a run at the Rolex FEI World Cup Sunday before trotting away from a 13-jump course which he finished almost flawlessly.

Then, in front of a gallery of fans, Hickstead gave way under Lamaze.

"We finished our round, I circled and was leaving the ring, and he collapsed and died," Lamaze said in a statement. "It is the most tragic thing that has ever happened. We had him until he was 15, and we had a great time together. He was the best horse in the world. We are all devastated."

The horrified crowd had to witness the horse lying on the ground in pain, hooves flailing in the air. There is video on the Internet, as always, but there's no need to show it here. There's no need to watch the death of the best equestrian horse in the world. Instead, here are Hickstead and Lamaze at their best, in the World Equestrian Games last year:

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There are no necropsy results yet, but experts say Hickstead likely had a massive coronary.

"The horse is a natural blood doper," Karyn Malinowski, the director of the Equine Science Center at Rutgers University in New Jersey, told the New York Times. "When the horse does an athletic event, it will automatically dump tons of red blood cells into the bloodstream. It's what makes the horse a fabulous athlete. And at the same time, because you have an increase, the blood does become thicker, and if the horse was prone to a weakened heart, it could have burst."

The stronger the horse, the more fragile he or she is. A stallion's legs don't grow to match its enormous girth, which makes every race and every leap a miracle and a risk. Whether it's Ruffian, Barbaro or Hickstead, the most unforgettable horses in history are made legendary because they ran to their limits, and couldn't run past them.

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