The Japan Racing Association said Saturday it would exclude 156 horses from racing this weekend, an unprecedented number, after finding a prohibited substance in their feed additives.
The JRA held its races as scheduled on Saturday, and will do likewise on Sunday with the remaining horses. A total of 983 were originally supposed to compete this weekend.
The association said an imported additive sold by Japanese company Nosan Corp. was found to contain a performance-enhancing substance called theobromine, a stimulant that also strengthens cardiac activities.