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Dosage: In Layman’s Terms / Wednesday, September 18, 2013

Owners, trainers, breeders, and handicappers rely on a plethora of data and information when evaluating horses. One of the most confusing, yet intriguing pieces of data is a horse’s dosage index.

Here’s the Cliff Notes version:

  • -A Dosage index is a mathematical figure used to quantify a horse’s ability to handle various distances based on the appearance of influential sires in the bloodline. The Dosage Index (DI) and related Center of Distribution (CD) largely represent the ratio of speed and stamina. The CD is a number between -2 and +2 which indicates the distance a horse could potentially be successful over.

  • -Sprinters typically have a higher DI, whereas routers display more stamina, thus displaying a lower DI.

  • -Elite Thoroughbreds often have lower DI and CD figures than the general population.

  • -The infusion of speed into Thoroughbred pedigrees is reflected in the rising DIs and CDs of classic winners over time.

  • -An influential sire (mentioned above) is determined not only by their achievements on the racetrack, but also by the proven, consistent ability of their offspring. There are currently 211 influential sires listed by Dr. Steven Roman (developer of the modern, improved Dosage version). These dominant sires are known as Chef-De-Races.

  • -The Chef-De-Races are grouped into five categories, with the Brilliant and Intermediate categories reflecting sprinters, the classic category reflecting horses who can handle classic distances, and the Solid and Professional categories referring to those horses with tremendous stamina. From this a five number dosage profile (DP) is created. From the DP, the DI is created.

  • -The five numbers of the DP show the spectrum of speed to stamina. A horse with a high Brilliant number will most likely excel at short distances. The more points to the right of the Brilliant and Intermediate numbers, the more apt a horse is to handle long distances.

Dosage Profile


Dosage profiles of some graded stakes winners:

Macho Again

DP = 5-2-5-0-0 (12) DI = 3.80   CD = 1.00


DP = 14-8-21-2-1 (46) DI = 2.41   CD = 0.70

Dream Rush

DP =12-8-10-0-2 (32) DI = 3.57   CD = 0.88

Twilight Eclipse

DP = 2-0-12-2-0 (16) DI = 1.00   CD = 0.13

Royal Delta

DP= 10-11-17-0-2 (40) DI = 2.81   CD = 0.68

Flashy Bull

DP= 5-2-7-0-0 (14) DI = 3.00   CD = 0.86

Awesome Gem

DP = 7-3-8-0-0 (18) DI = 3.50   CD = 0.94

Animal Kingdom

DP = 2-0-6-0-0 (8) DI = 1.67   CD = 0.50

Wise Dan

DP= 1-3-4-2-0 (10) DI = 1.50   CD = 0.30

St. Nicholas Abbey

DP = 3-1-18-12-0 (34) DI = 0.62   CD = -0.15

Yes It’s True

DP = 9-3-2-0-0 (14) DI = 13.00   CD = 1.50

City Zip

DP = 21-11-11-1-0 (44) DI = 5.77   CD = 1.18

Does anything jump out at you when evaluating these DPs, DIs, and CDs? Leave a comment below and let us know.

Intrigued and want to learn about Dosage Indexes in more detail?

Brisnet Explanation of Dosage

The Dosage Method – The Alternative Analysis Tool

How Much Does It Cost to Own A Racehorse With West Point Thoroughbreds?

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