Eskenforadrink, the even-money favorite, was euthanized after suffering a severe leg injury while leading a one-mile race for $16,00 claimers in Saturday's third race, according to track stewards.
Eskenforadrink was taken to the stables for evaluation, but could not be saved, stewards said.
The injury occurred on a day in which the track is listed as sloppy and sealed after extensive morning rain.
Eskenforadrink was nearing the turn when she was stricken and quickly brought to a halt by jockey Geovanni Franco. The incident did not affect the other five runners.
Eskenforadrink, who was trained by Jorge Gutierrez, is the 20th equine fatality in training and racing at Santa Anita since Dec. 26. Earlier this week, the track was closed for training late Monday and all of Tuesday and Wednesday to inspect the surface following four fatalities from Feb. 22 to Monday. Training resumed on Thursday after track officials said they found no irregularities in the surface.
Racing was conducted on Thursday and Friday without incident. There was no training on Saturday morning because of the early morning rain.
Eskenforadrink won 2 of 12 starts.