2011: two-year-old season Dullahan was slow to show worthwhile form as a two-year-old, being well beaten in minor events at
Churchill Downs in June and July. He then moved to
Saratoga where he finished second in a maiden race before finishing third in the
Grade II With Anticipation Stakes on turf in September. Despite having failed to win in four starts, he moved up to Grade I level for the
Breeders' Futurity Stakes at Keeneland. Ridden by
Kent Desormeaux, he was held up in the early stages before finishing strongly to take the lead near the finish and won by three-quarters of a
length from Majestic City. He was badly hampered and almost fell in the early stages but recovered well, leading Desormeaux to describe him as a "super horse". In the
Breeders' Cup Juvenile at Churchill Downs on 5 November, Dullahan started a 16/1 outsider and stayed on in the straight to finish fourth of the thirteen runners behind
Hansen,
Union Rags and
Creative Cause.
2012: three-year-old season Dullahan made his first appearance as a three-year-old at
Gulfstream Park in March, where he finished second to Howe Great in the Grade III
Palm Beach Stakes. A month later, he was sent to Keeneland to contest the Blue Grass Stakes, in which he was matched against the
Eclipse Award winner Hansen for the second time. In front of a record crowd of 40,617, Desormeaux restrained the colt in the early stages before moving him up to overtake Hansen near the finish and win going away by one and a quarter lengths.
USA Today described his performance as "scintillating" and reported that Romans felt that Dullahan was by far his best chance of winning the Kentucky Derby. In the Derby, Dullahan started at odds of 12/1 in a field of twenty. He raced in the middle of the field before being switched to the outside in the straight. He made steady progress to finish third behind
I'll Have Another and
Bodemeister. Dullahan skipped the Preakness to go straight for the
Belmont Stakes on June 9. Following the late withdrawal of "I'll Have Another", he was made the favorite for the race, but finished fifth behind
Union Rags. After a seven-week break, Dullahan returned in the Haskell Invitational Stakes at Monmouth Park, in which he finished seventh, behind
Paynter. A month later, he was tested against older horses in the TVG Pacific Classic at
Del Mar Racetrack and won by half a length from
Game On Dude in a new track record time of 1:59.54. It was Dullahan's third Grade I win, all of them achieved on a
synthetic surface, and gave the colt automatic entry into the
Breeders' Cup Classic. Dullahan's two remaining starts as a three-year-old were disappointing: he finished fifth when favorite for the
Jamaica Handicap at Belmont in October and then ran ninth, behind
Little Mike in the
Breeders' Cup Turf.
2013: four-year-old season Dullahan was sent to race in the United Arab Emirates in March 2013 but ran poorly in his two races, including the
Dubai World Cup in which he finished eleventh of the twelve runners behind
Animal Kingdom. On his return to the US, he finished third in the Grade III Arlington Handicap but then finished eighth behind Game On Dude when he attempted to repeat his 2012 success in the Pacific Classic. Dullahan sustained a tendon injury in the Pacific Classic and was retired from racing on October 14. Six days later, the colt suffered a severe attack of
colic in his stable. Despite prompt medical attention and surgery, he was euthanized at 4:45 am on October 20. According to a Facebook post by Dale Romans, Dullahan was regarded by those who knew him as an incredible horse – full of personality and talent. "Love you, Dullahan – our thoughts and prayers are with you, buddy !! ==Pedigree==