That said, one of the most remarkable champions the racing world has ever seen also retired last year -- a female thoroughbred called Black Caviar.
The Australian mare notched up 25 consecutive wins, becoming not just a national sports star but a celebrity who even graced the cover of Vogue magazine.
"Her allegiance level is phenomenal," Colin Madden, one of Black Caviar's eight owners, said. "She's a powerful horse who just fronts up every time and people really like that consistency."
The girls may have some way to go in catching the boys. But it seems that even in the equine world, the race is far from over.