Uncle Mo, the champion 2-year-old male of 2010 and a record-setting sire, was euthanized Thursday after suffering a left foreleg injury. 

Owner Mike Repole made the announcement on his social media channels on midday Thursday, noting the 16-year-old son of Indian Charlie underwent surgery Wednesday before the decision was made to not continue pursuing recovery. 

He went unbeaten in three starts as a 2-year-old, romping on debut in a Saratoga Race Course maiden special weight by 14 1/4 lengths, then winning the Grade 1 Champagne Stakes at Belmont Park by 4 3/4 lengths. He then cemented himself at the top of his class with a commanding 4 1/4-length score in the 2010 Breeders’ Cup Juvenile at Churchill Downs, which secured him the Eclipse Award as champion 2-year-old male of that season. 

Uncle Mo returned in August of his 3-year-old season, and he scaled back in distance for the G1 King’s Bishop Stakes at Saratoga, where he got nipped at the wire by a nose behind Caleb’s Posse. He then faced older competition for the first time in the G2 Kelso Handicap, which he won by a front-running three lengths, before finishing his career with an out-of-the-money effort in the Breeders’ Cup Classic at Churchill Downs. 

Uncle Mo was retired in the days following the Breeders’ Cup after blood tests revealed elevated enzymes similar to what he had experienced in the spring. He finished his career with five wins in eight career starts for earnings of $1,606,000. 

Uncle Mo has sired 59 graded/group stakes winners, including 2022 Belmont Stakes winner Mo Donegal, Kentucky Derby winner and prominent sire Nyquist, two-time Breeders’ Cup winner Golden Pal, and Grade 1 winners Adare Manor, Arabian Knight, Kingsbarns, Unbridled Mo, Mo Forza, A Mo Reay, Bast, Yaupon, Outwork, Gomo, and Mo Town.