Championship horse Barbaro was recently euthanized after complications that followed his fall in May's Preakness Stakes.
Although his owners and trainers have always remained utterly beyond suspicion for Barbaro's death, his unexpected collapse has brought some issues to light about the horse-racing industry in the United States.
Every year hundreds of horses collapse on American racing tracks after leaving the starting gate, and many die.
There were, on average, 1.5 deaths for every 1,000 starts in American racing, according to various studies conducted at around 10 American racecourses over the last few seasons.
One Illinois racetrack recorded 21 fatalities last season, and California's Del Mar summer season ended with the loss of 16 horses.
While no exact figures exist for 2006, data from the U.S. Jockey Club in New York suggest about 600 horses died racing-related deaths on U.S. racetracks in 2006.
That's a staggering figure when compared with the death rates at famous racing spots around the world.
Over the last five years, Hong Kong's renowned Jockey Club recorded a significantly lower 0.58 deaths per 1,000 race starts -- or just 26 fatalities.
So what's behind the higher death rate among U.S. racehorses? The widespread use of medicinal drugs in American racing may be to blame, according to some experts.
"Are we a little bit more permissive than Europe and Asia?" asked Dr. Scott Waterman of the Racing Medication Testing Consortium. "Yes. For example, it's legal to administer a drug called Salix to horses on race day, which is used to control 'bleeding,' an exercise-induced pulmonary hemorrhage, in which a horse's capillaries burst in the lungs."
According to Waterman, the use of drugs like Salix can improve a horse's performance. "You're trying to let the horse compete -- blood in the lungs will mean that oxygenation does not proceed as before."
And that's not all. Some trainers use drugs that are illegal in some states, outlawed in horse racing outside the United States, and in some cases designed for humans, not horses.
One such drug, manufactured by U.S. biotechnology firm Amgen, is Epogen.
According to Dr. Rick Arthur, a medical director at the California Horse Racing Board, Epogen is "a peptide hormone that stimulates the bone marrow to produce red blood cells," which in turn can improve oxygen levels.
According to Arthur, Epogen is also "the drug cyclists are often accused of using." In California, horses now are tested for this drug.
An Amgen spokeswoman said: "We are aware of cases where people are unfortunately using Epogen with horses, and it's actually even more dangerous. It's something that we very strongly discourage."
Injecting a foreign protein into the animal, she explained, means that ultimately some horses can become "transfusion dependable."
Snake venom has even been used as an untraceable painkiller for horses, according to some equine professionals.
"It's been on the rumor mill for a while, but is extremely difficult to detect," Waterman said. "You will always have some unscrupulous individuals who seek to take advantage. That's a problem not only for U.S. racing but for racing globally."
However, recent reports from the Saratoga Gaming and Raceway in upstate New York suggest that U.S. trainers are indeed using snake venom to numb a horse's pain, and also -- crucially -- to beat local doping restrictions.
But Luca Cumani, an Italian trainer now based in Britain, is unconvinced that snake venom could be effective.
"It's something that's been around for years, but there are much more sophisticated drugs that have been applied to horses," he said.
Roy and Gretchen Jackson, Barbaro's owners, are based in West Grove, Pa. They are above suspicion of any such drug use, say U.S. horse-racing experts, but other high-flying trainers have recently run afoul of racing authorities.
Todd Pletcher, whose horses took in about $30 million in 2006, became the most successful U.S. trainer that year. However, he was given a 45-day suspension in December, after one of his horses tested positive for an anesthetic drug while racing at Saratoga in August 2004.
The New York State Racing and Wagering Board still imposed the suspension despite two major appeals.
The lines between legitimate medication and illegal drug use in American racehorses are further blurred by conflicting state laws.
Italian trainer Cumani says that the distinction in U.S. racing is itself complicated. "It is a very emotional word, since all these medications are lumped into the term 'drugs.' You say that a horse is on drugs, and it immediately conjures up all sorts of things. Right now, the authorities are not up to tackling the difference between drugs and medication," he said.
Phenylbutazone, commonly known as "bute," is another drug that can be misused by American trainers.
However, Waterman said he believed the use of painkillers on horses slated to race on a given day was now very unusual.
But Brian Meehan, a British trainer whose horses have scored notable successes at the Kentucky Derby in recent years, does not believe there is any problem with the American drug allowances in racing.
"Once you know the limits and the regulations, there should be no problems," he said.