A horse due to take part in this week's Breeders' Cup in California died suddenly on Tuesday shortly before Belmont Stakes winner Arcangelo scratched from the meeting's $6 million Classic.

A statement from Breeders' Cup organizers said Practical Move, who was due to compete in the Dirt Mile, died after suffering a suspected cardiac arrest following a morning gallop at Santa Anita Park.

"Breeders' Cup is saddened to report the loss of Practical Move after what is suspected to be a cardiac event while returning from his gallop this morning at Santa Anita Park," the statement said.

"His rider was uninjured, and the horse was immediately tended to by veterinarians from the California Horse Racing Board (CHRB), 1/ST Racing, and Breeders' Cup."

The death of Practical Move cast a somber pall over preparations for this week's racing festival, reviving memories of the slew of equine fatalities at Santa Anita in recent years.

Dozens of horses died in racing at Santa Anita, just outside Los Angeles, in 2019 although an investigation by local prosecutors later found no evidence of criminal wrongdoing or animal cruelty.

In a separate development on Tuesday, Belmont Stakes winner Arcangelo was withdrawn from this week's meeting after failing to recover from an injury to his left hind hoof.

Trainer Jena Antonucci told the TVG betting site that the three-year-old had "run out of time" to be ready for the race.

"As we've talked about from day one, we will always be horse first, no matter absolutely what," Antonucci said.

"We need to do right by him. And missing a race is gonna be what it's gonna be this time... I'm not comfortable and if I'm not comfortable then it's a no."

Arcangelo's withdrawal reduces the Breeders Cup Classic field to 11 horses. Kentucky Derby winner Mage was also expected to run in the event but did not travel to California after suffering a fever.

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