Pioneerof the Nile, sire of American Pharoah, dead at 13

Multiple Grade 1 winner and classic-placed Pioneerof the Nile, the sire of 2015 Triple Crown winner American Pharoah and 2016 champion juvenile colt Classic Empire, unexpectedly died Monday at the age of 13.

Pioneerof the Nile bred a mare Monday morning and "started acting uncomfortable once he was back in his stall," according to a release from WinStar Farm. Pioneerof the Nile died en route to a clinic.

"We are all extremely saddened by the loss of Pioneerof the Nile," said WinStar's Elliott Walden. "He was a superior physical specimen, a Triple Crown sire, and a unique personality. All of us at WinStar are heartbroken."

"He was not only my first homebred he was one of my GREATEST," owner-breed Ahmed Zayat said on Twitter. "He is gone way too soon, but never to be forgotten. It truly does take a Pioneer. My sweet boy."

Pioneerof the Nile, a son of 2003 Belmont (G1) winner Empire Maker, was standing for a fee of $110,000 this year.

Like his father, Pioneerof the Nile would finish second in the Kentucky Derby (G1) after two previous wins at the Grade 1 level. Pioneerof the Nile earned place honors behind longshot Mine That Bird in the 2009 Run for the Roses having previously won the Hollywood Futurity (G1) and Santa Anita Derby (G1). He also captured the San Felipe (G2) and Robert B. Lewis (G2), and was retired after finishing 11th to the Horse of the Year Rachel Alexandra in the Preakness (G1).

In addition the Zayat-owned American Pharoah, a champion at two and Horse of the Year at three, and Classic Empire, who finished second in the Preakness at three, Pioneerof the Nile has also sired Grade 1 turf winner Midnight Storm and multiple Grade 2-winning sire Cairo Prince, among others.