Japan's racing industry was shocked by the news Tuesday of the death of its leading sire, Agnes Tachyon, found dead in his stall at Shadai Stallion Station in Hokkaido's Abira-cho on Monday afternoon.

The cause of death had yet to be determined but heart failure was suspected. The 11-year-old Tachyon was considered the next pillar of Japanese breeding, following in the steps of his sire, the late American champion Sunday Silence.

Tachyon swept the first three races of his career before capturing the 2001 Satsukisho, the Japanese equivalent of the 2,000 Guineas. It was to be his last race, with tendinitis forcing the colt's early retirement.

Agnes Tachyon's progeny, however, including such top runners as four-time Group 1 winner Daiwa Scarlet and 2008 Nippon Derby winner Deep Sky, have enjoyed stellar careers. Last year, the combined earnings of 140 winners from 322 Agnes Tachyon-sired runners amounted to over ¥3.47 billion in prize money and put Tachyon at the top of Japan's stallion rankings. Just completing his eighth season as a stallion, Tachyon had enjoyed his top season last year, covering 230 mares.