Grindstone is a thoroughbred

Thoroughbred

The Thoroughbred is a horse breed best known for its use in horse racing. Although the word thoroughbred is sometimes used to refer to any breed of purebred horse, it technically refers only to the Thoroughbred breed...

 racehorse who won the Kentucky Derby

Kentucky Derby

The Kentucky Derby is a Grade I stakes race for three-year-old Thoroughbred horses, held annually in Louisville, Kentucky, United States on the first Saturday in May, capping the two-week-long Kentucky Derby Festival. The race is one and a quarter mile at Churchill Downs. Colts and geldings carry...

 in 1996. He became jockey

Jockey

A jockey is an athlete who rides horses in horse racing or steeplechase racing, primarily as a profession. The word also applies to camel riders in camel racing.-Etymology:...

 Jerry Bailey's

Jerry Bailey

Jerry D. Bailey is a retired American Hall of Fame jockey. He began his racing career in November 1974. His first mount was on a horse named Pegged Rate, who ran off the board. He notched his first career win the next day on his second career mount, Fetch, at New Mexico's Sunland Park, and has...

 2nd Kentucky Derby winner and the second in a row for trainer D. Wayne Lukas

D. Wayne Lukas

Darrell Wayne Lukas is a former educator who became one of the most successful horse trainers in American Thoroughbred horse racing history and a U.S...

.

Bred and owned by William T. Young's

William T. Young

William T. Young was an American businessman and major owner of thoroughbred racehorses.William T. Young attended the University of Kentucky where he was a member of the Sigma Alpha Epsilon fraternity. Young graduated with high distinction in 1939 with a Bachelor of Science in mechanical...

 Overbrook Farm, Grindstone was the son of Unbridled

Unbridled

Unbridled was a Champion American Thoroughbred racehorse.The colt was sired by Fappiano , by Mr. Prospector, and his dam Gana Facil, by Le Fabuleux. Unbridled retired with a career record of 8 wins, 6 places and 6 shows in 24 starts, and $4,489,475 in career earnings...

 out of the mare Buzz My Bell. Prior to the Derby, Grindstone had won the Louisiana Derby

Louisiana Derby

The Louisiana Derby is an American Thoroughbred horse race run annually at the Fair Grounds Race Course in New Orleans, Louisiana. Usually run in early March, the race is open to horses, age three, willing to race 11/8 miles on the dirt. A Grade II event, it currently offers a purse of...

 and was second in the Arkansas Derby

Arkansas Derby

The Arkansas Derby is an American flat Thoroughbred horse race for three-year-olds held annually at Oaklawn Park in Hot Springs, Arkansas. It is currently a Grade I race run over a distance of 9 furlongs on dirt....

.

Grindstone was retired just 5 days after his Kentucky Derby victory when knee chips were discovered in his leg. He is the first horse since Bubbling Over in 1926 to be retired immediately following a win in the Kentucky Derby. He stands today at Oakhurst Farm in Oregon (making him the first Kentucky Derby winner to ever stand in the Northwest). His progeny include two millionaires, GR I winner Birdstone

Birdstone

Birdstone is an American Thoroughbred racehorse best known for winning the 2004 Belmont Stakes and is gaining notoriety as a fantastic sire....

 and Ekolu Place. He is also, via Birdstone, the grandsire of Mine That Bird

Mine That Bird

Mine That Bird is a retired American racehorse. He is best known for being one of only nine geldings to win the Kentucky Derby, and the second gelding to win the race since 1929...

 and Summer Bird

Summer Bird

Summer Bird is a retired American Thoroughbred racehorse, son of 2004 Belmont Stakes winner Birdstone. He was bred by retired cardiologist Kalarikkal Jayaraman and his wife, retired pathologist Vilasini Jayaraman, at their Tiffany Farm near Ocala, Florida...

, who both won Triple Crown races in 2009.