ARCADIA (CBSLA) — Sen. Dianne Feinstein is calling for racing to be suspended at Santa Anita Park after the deaths of 23 horses since late December.

In a letter to the state’s horse racing board, Feinstein asked for racing to be suspended until the cause or causes of the horse deaths can be fully investigated in her letter sent Tuesday to the California Horse Racing Board, which hours later scheduled a special meeting to consider relocating races to other tracks.

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“The death of a single horse is a tragedy, but as a lifelong lover of horses, I’m appalled that almost two dozen horses have died in just four months,” Feinstein wrote in her letter.

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Nearly two dozen horses have died at the Arcadia racetrack, most recently on Sunday – just two days after Santa Anita Park reopened after a nearly month-long hiatus. Racetrack officials have not been able to pinpoint any one factor causing the deaths, investigating everything from the effect of unusually heavy rain this winter on the track to race-day medication.

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Before Santa Anita Park reopened, the state horse racing board discussed new rules that could ban or restrict the use of whips and riding crops. One rule that went into immediate effect reduced the use of a medication called Lasix, a diuretic that helps prevent horses from hemorrhaging.