California horse racing regulators said Wednesday they will require all horses to undergo independent reviews before they're allowed to race at the famed Santa Anita Park, where 29 horses have died or have been put to death since Christmas.

There were 26 equine deaths at the famed track in the 2017-18 season, and there are still two more weekends of racing to go this year. Santa Anita suspended racing for nearly a month in March to examine the racing surface.

No cause has been pinpointed for the deaths, and Russ Heimerich, a spokesman for the state Business, Consumer Services and Housing Agency, which oversees the racing board, said Wednesday that nothing had been ruled out.

The new measures were announced a day after Gov. Gavin Newsom called on the California Horse Racing Board to ensure that no horse was allowed to race until it was independently examined for fitness by a veterinarian. Sen. Dianne Feinstein, D-Calif., has also repeatedly asked for racing to be shut down at Santa Anita.

The horse racing board and the track's owner, the Stronach Group, said Wednesday that independent teams of five veterinarians and stewards would review every horse's medical, training and racing history.

Each review team, which will include at least two veterinarians, will be authorized to scratch a horse if just one team member decides it doesn't appear fit to run, said Rick Baedeker, executive director of the board, called the measures "historic," and Business, Consumer Services and Housing Secretary Alexis Podesta called it "unprecedented in American horse racing."

Podesta said she expected the Santa Anita plan to become the industry standard.

The racing board said over the weekend that it had "recommended to Santa Anita management that they suspend racing for the seven remaining race days but that they allow horses to continue to train during that period." Stronach said Sunday night that it had no intention of closing down the races.

Kathy Guillermo, senior vice president of the activist group People for the Ethical Treatment of Animals, said Wednesday that the organization agreed on the need for "independent veterinarians who are not part of the 'drug 'em and race 'em' culture." But she said racing should be suspended across the state pending an investigation by the Los Angeles County district attorney's office.