The Dosage Index (DI) represents a racehorse's pedigree and inclination toward speed or stamina. Breeders, trainers, and handicappers use it to assess a horse's potential for success in various races, including prestigious events like the Preakness Stakes. Check out my Kentucky Derby article to learn more about a horse's DI (dosage index).


Looking back at the Preakness Stakes results over the past two decades, it's clear that the Dosage Index has played a significant role in determining the race's outcome. The only horse to win the Preakness with a Dosage Index over 4.00 in the last 22 years was American Pharoah in 2015, with a DI of 4.33. He was an outlier, winning the Triple Crown.


It's worth noting that some Preakness winners have had lower Dosage Index (DI) values, indicating that these horses were better suited for endurance rather than speed. For example, in 2023, National Treasure won with a DI of 2.56, while Early Voting triumphed in 2022 with a DI of 1.00. These lower DI values suggest these horses were likelier to perform well in longer races.


The 2021 winner, Rombauer, had a DI of 1.86, while Swiss Skydiver in 2020 possessed a DI of 2.00. War of Will, the victor in 2019, had a DI of 1.72, further emphasizing the trend towards lower Dosage Index values among recent Preakness champions. Here's the field for Saturday's 149th Preakness Stakes with Dosage.


#1 Mugatu (3.00)


#2 Uncle Heavy (7.00)


#3 Catching Freedom (5.67)


#4 Muth (3.00)


#5 Mystik Dan (3.00)


#6 Seize the Grey (6.11)


#7 Just Steel (4.00)


#8 Tuscan Gold (3.00)


#9 Imagination (11.00)


The Dosage Index is a valuable tool for assessing a horse's potential, but it's important to remember that it's not the only predictor of success. Understanding other factors such as training, jockey skill, track conditions, and race strategy is equally important in determining the outcome of the Preakness Stakes.


Past Preakness winners with Dosage since 2002:                           


2023: National Treasure, DI of 2.56

                                            2022: Early Voting, DI of 1.00

2021: Rambauer, DI of 1.86

2020: Swiss Skydiver, DI of 2.00

2019: War of Will, DI of 1.72

2018: Justify, DI of 3.00

2017: Cloud Computing, DI of 3.36

2016: Exagggerator, DI of 3.40

2015: American Pharaoh, DI of 4.33

2014: California Chrome, DI of 3.46

2013: Oxbow, DI of 2.50

2012: I'll Have Another, DI of 2.11

2011: Shackleford, DI of 3.62

2010: Lookin at Lucky, DI of 3.33

2009: Rachel Alexandra, DI of 1.55

2008: Big Brown, DI of 1.67

2007: Curlin, DI of 4.00

2006: Bernardini, DI of 3.31

2005: Afleet Alex, DI of 2.11

2004: Smarty Jones, DI of 3.40

2003: Funny Cide, DI of 1.53

2002: War Emblem, DI of 3.40


The 22-year average dosage is 2.69.


Follow Jeff on X @JHSPORTSLINE