A 24th horse has died at Santa Anita, the first since March 31.
Commander Coil broke down during training hours Friday, sustaining a shoulder injury while galloping that required the 3-year-old gelding to be euthanized, according to a statement from The Stronach Group, which owns the track.
The statement called it an "uncommon injury."
The horse had not yet made his racing debut. He was trained by Marcelo Polanco and owned by Jose Romero.
The track had gone six weeks without a horse fatality. Since various reforms involving race-day medication and safety were instituted on March 15, The Stronach Group says there have been over 80,000 gallops during training with no fatalities.
The previous fatality occurred March 31 when Arms Runner fell during a turf race.
A total of 24 horses have died since Dec. 26.
Also Friday, a 3-year-old filly named Congrats Gal collapsed just past the finish line of the Miss Preakness Stakes at Pimlico in Baltimore, a track also owned by The Stronach Group.
No cause of death was immediately announced.
A necropsy will be performed on both horses.