Dosage Explanation

By Steve Miller


The Dosage system

The Dosage system is a useful tool in the assessment of the distance potential of racehorses, based on certain sires (those that demonstrate prepotent influence) in the first four generations of an individual’s pedigree. It is especially useful when form information is either scant or absent. It also helps in identifying if a racehorse is being campaigned over a less effective distance than it is ideally suited. Three statistics are generated by the Dosage system: a Dosage Profile (DP), a Dosage Index (DI) and a Centre of Distribution (CD). Qualifying CDRs are divided into five categories: Brilliant, Intermediate, Classic, Solid and Professional. The categories correspond to a range of distance potential, from Brilliant (most speed, least stamina) to Professional (least speed, most stamina). Classic represents a balance of speed and stamina. Chefs may be assigned to one or two categories (as with Galileo, a Classic/Solid), with points split between the categories. A chef-de-race (CDR) in the first generation is assigned 16 points, decreasing to eight, four and two points, to account for the diminishing influence of sires further back in the pedigree.

What makes a chef-de-race?

In the Dosage system a chef-de-race (chief of breed) is a stallion that transmits a ‘prepotent’ (over and above that generally seen) influence at a particular distance range on his offspring as a group. The larger the sample and the more specific the distance range, for any given stallion, the more compelling a case for that stallion to be included as a CDR. Occasionally (as with Galileo, for example) a stallion may have more than one string to his bow and show a strong (albeit twin) focus at two distances ranges. Such stallions are said to exert a ‘split influence’ for their offspring as a group. Galileo is a split Classic/Solid influence (i.e. transmitting an influence for classic speed at around 8-9 furlongs as well as an influence for middle distance stamina at around 10-12 furlongs). Many stallions show a much more even distribution of influence across the distance range from sprint distances to extreme stamina, depending on which mare they are matched to. Such stallions (good as they might be) do not exert prepotent influence and therefore cannot be considered for the CDR list. Those stallions who do stamp a particular distance focus on their progeny, almost irrespective of which mares they are matched to, are considered to be influencing the breed to a greater extent than non-CDR stallions. The presence of such CDR stallions in the pedigree of any given individual exert a disproportionate influence and are given greater weight in an analysis of an individual’s stamina potential. This helps us to look past the sort of analysis that only considers what a mare may have produced from an often, at best, small handful of offspring.

Steve Miller

More on the Dosage system from Steve Miller and Dr Steven Roman can be found at and in the book Dosage: Pedigree and Performance, published by The Russell Meerdink Company, Ltd.

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