Horatio Nelson was a racehorse

Horse racing

Horse racing is an equestrian sport that has a long history. Archaeological records indicate that horse racing occurred in ancient Babylon, Syria, and Egypt. Both chariot and mounted horse racing were events in the ancient Greek Olympics by 648 BC...

 sired by Danehill

Danehill (horse)

Danehill was a Thoroughbred racehorse who was bred in the United States. During his phenomenal stud career Danehill became a champion sire on both sides of the Equator...

, out of the Irish 1,000 Guineas and Epsom Oaks

Epsom Oaks

The Oaks Stakes is a Group 1 flat horse race in Great Britain open to three-year-old thoroughbred fillies. It is run at Epsom Downs over a distance of 1 mile, 4 furlongs and 10 yards , and it is scheduled to take place each year in early June....

 winner Imagine. His owners were John Magnier

John Magnier

John Magnier is Ireland's leading thoroughbred stud owner and has extensive business interests outside of the horse breeding industry....

 and David Nagle. The colt

Colt (horse)

A colt is a young male horse, under the age of four. The term "colt" is often confused with foal, which refers to a horse of either sex under one year of age....

 won four of his seven starts, including the Prix Jean-Luc Lagardère

Prix Jean-Luc Lagardère

The Prix Jean-Luc Lagardère is a Group 1 flat horse race in France which is open to two-year-old thoroughbred colts and fillies. It is run at Longchamp over a distance of 1,400 metres , and it is scheduled to take place each year in early October.It is the oldest and most prestigious race in France...

 at Longchamp Racecourse in October 2005. He competed in the 2006 Epsom Derby

Epsom Derby

The Derby Stakes, popularly known as The Derby, internationally as the Epsom Derby, and under its present sponsor as the Investec Derby, is a Group 1 flat horse race in Great Britain open to three-year-old thoroughbred colts and fillies...

 but broke down during the race and was later euthanized

Animal euthanasia

Animal euthanasia is the act of putting to death painlessly or allowing to die, as by withholding extreme medical measures, an animal suffering from an incurable, especially a painful, disease or condition. Euthanasia methods are designed to cause minimal pain and distress...

. He sustained a fractured cannon bone, a sesamoid bone

Sesamoid bone

In anatomy, a sesamoid bone is a bone embedded within a tendon.Sesamoids are found in locations where a tendon passes over a joint, such as the hand, knee, and foot. Functionally, they act to protect the tendon and to increase its mechanical effect. The presence of the sesamoid bone holds the...

 and a dislocated fetlock joint on his right fore leg.