The home team from the United Arab Emirates lost their chance when Sheikh Mohammed and one of his sons were eliminated at the third gate, about three-quarters of the way through the 100-mile race in the desert.
The American rider Valerie Kanavy regained the individual title of World Endurance Champion on High Winds Jedi after the defending champion, her daughter Danielle, retired when her horse took a tumble in the Dubai desert.
The younger Kanavy, who won the title on Peirez four years ago in Kansas, dropped out after her 16-year-old grey gelding, Peirez, fell two miles from the first veterinary checkpoint in the $300,000 (pounds 190,000) race.
No fewer than 174 riders set off at the crack of dawn at the Abu Dhabi town of Ghantoot and endured high temperatures as they steered their mounts along the 160km (99 mile) course.
Valerie and Danielle Kanavy have both won the World Championship on Peirez before, and Valerie Kanavy's win maintains the American hold on the championship since the first competition in 1986.
Fausto Fioricci, a doctor from Italy, was the outsider in the field, finishing second on Faris Jabar, with Japan's Daisuke Yasunaga in third.
No official timings were released by the organisers. A computer failure meant riders were left without waiting periods for the next stages.
Dubai's Crown Prince, Sheik Mohammed bin Rashid Al Maktoum, saw his hopes disappear when his horse, Nelson I, failed an examination at the fourth checkpoint.Reuse content