Bred by Edward B. Benjamin in Greensboro, North Carolina, the bay colt was born with a noticeably crooked foreleg, so was considered to have no future in racing.
Purchased by Edgar Caibett, the horse was shipped to his owner's native Venezuela, where he earned an undistinguished record racing as a two-year-old in La Rinconada Hippodrome.
Trained by Juan Arias and ridden by jockey Gustavo Avila, in the spring of 1971, the horse was shipped to Louisville, Kentucky, for the big race.
There, Cañonero II was dismissed as a horse that did not belong in such elite company and was listed at the bottom of the pack of the betting odds as part of a six-horse pool.
However, due to a foot infection that had bothered the horse for several days, Cañonero II, after taking the race lead, struggled across the finish line in fourth place.