Uncle Mo, Champion and Top Sire, Dead at 16

Farewell to Uncle Mo, gone too soon but never to be forgotten.

The 16-year-old world-class stallion was euthanized Thursday morning in Kentucky after undergoing surgery for an injured left foreleg on Wednesday.

Owner Mike Repole announced the death on X:

“I am devastated and saddened to share with you that Uncle Mo was euthanized earlier today. Unfortunately, the surgery process was too much for him to endure.

“The Repole Stable family, (trainer) Todd Pletcher and the entire Coolmore family are heartbroken. Uncle Mo was so much more to me than a champion and iconic stallion – he was and always will be a part of my family …

“Uncle Mo is the patriarch of Repole Stable. There will never be another horse that makes me feel or will impact my life the way that Uncle Mo has.”

Champion on the track

The son of Indian Charlie was an unbeatable 2-year-old, a Breeders’ Cup Juvenile (G1) champion with unlimited potential. Repole dreamed of sweeping the Triple Crown, but a rare liver ailment kept his first star out of the classics and eventually ended his career after his 3-year-old season.

Uncle Mo retired with five wins, including four stakes, in eight starts and earnings of $1.6 million. But as brilliant as he was on the track, he was infinitely greater as a breed-shaping phenomenon for Coolmore’s Ashford Stud.

I am devastated and saddened to share with you that Uncle Mo was euthanized earlier today following a left foreleg injury.

He had surgery yesterday. Unfortunately, this morning the recovery process was too much for him to endure.

The Repole Stable family, Todd Pletcher… pic.twitter.com/ZHIo0yJGn8

— Repole Stable (@RepoleStable) December 19, 2024

Instant success as a sire

He was an instant success, siring horses who could excel on turf and dirt, on fast and wet tracks, going short or going long. He’s also emerging as a top broodmare sire, ensuring his influence for many years to come.

As pedigree expert Alan Porter wrote Dec. 16 on bloodhorse.com: “Uncle Mo made one of the most remarkable starts to his stud career of any stallion in recent memory. From his first crop he was represented by no less than 25 individual black-type winners.”

The best of them was Nyquist, only the second horse to sweep the Breeders’ Cup Juvenile (in 2015) and the Kentucky Derby (G1).

Uncle Mo has sired 109 stakes winners, including 15 who earned Grade 1 trophies. He finished among the top four American-based sires overall in 2016, 2020, 2022 and 2023. Among his distinguished progeny are Belmont Stakes (G1) hero Mo Donegal, turf champion Golden Pal and standout mare Adare Manor. Uncle Mo also sired Sataves, the dam of 2024 Horse of the Year candidate Thorpedo Anna.

Had he been healthy and in top form, Uncle Mo would have been the favorite for the 2011 Kentucky Derby, but a gastrointestinal problem forced Pletcher to scratch him the morning of the race.

Trainer Graham Motion won that Derby with Animal Kingdom. On Thursday, Motion tweeted:

“Will never forget running into Todd just before the Derby draw and him telling me Uncle Mo might be a scratch. The rest is history; who knows how great a racehorse he might have been. We all know what a brilliant sire he has been. Huge loss.”

Owner Mike Repole: ‘A special racehorse’

Repole, one of the world’s leading owners, never hides his feelings, win or lose. Losing his horse of a lifetime was a brutal hit, but he found solace in what Uncle Mo meant to him.

“Thank you, Uncle Mo, for fulfilling my childhood dream of owning a special racehorse,” he wrote on X. “I love you, Uncle Mo. Rest in Peace.”

US Racing Team

The writing team at US Racing is comprised of both full-time and part-time contributors with expertise in various aspects of the Sport of Kings.