In his final non-walkover race, the 150 Guineas at Newmarket in 1770, the undefeated Eclipse was offered odds of 1/70. These odds seem remarkable. Are there prominent examples of shorter odds in top-class horse-racing? Maybe in more recent races?
The lowest I could find was Man o' War from 1920, winning with 1/100 odds.
Just ten days later, Man o' War returned in the Stuyvesant Handicap which he won easily against only one rival. His odds of 1 to 100 were believed to be the lowest ever offered in an American horserace