What is dosage?
The father of dosage was Lt. Col. J.J. Vuillier, who identified stallions who showed up frequently in the pedigrees of European classic winners. He called these stallions "chefs-de-race" or "chiefs of the breed."
Then Dr. Franco Varola introduced aptitudinal analysis to Vuillier's concept. He created five aptitudinal categories – Brilliant, Intermediate, Classic, Solid, Professional – and began to place influential stallions in the various categories by their influence on their progeny. He also created dosage diagrams with point calculations, but without distinguishing between generations.
In the late 1970's Steven Roman developed more elaborate calculations associated with dosage profiles. Using just the first four generations, he assigned points given a particular chef by generation – 1st: 16 points, 2nd: 8 points, 3rd: 4 points, and 4th: 2 points. He then created the DI (dosage index) and the CD (center of distribution). Both indexes measure speed vs. stamina in a pedigree. Basically, the higher the DI and CD, the more speed and less stamina an individual will have. The lower the DI and CD, the less speed and more stamina a runner will have. Currently, Roman's chef list includes 209 stallions.
Leon Rasmussen began to feature Roman's dosage concepts in his Daily Racing Form column Bloodlines. Roman had shown that no horse had ever won the Kentucky Derby with a DI of over 4.00. Dosage's popularity grew like wild fire throughout the 1980's as every top contender, including several strong favorites, with DI's over 4.00 lost the Kentucky Derby. Along the way, dosage became something that it was not really intended by Roman to be – a "theory" to plan matings.
But, the 1990's proved to be demise of the Derby/dosage mystique when three of the 10 Kentucky Derby winners had DI's over 4.00 – Strike the Gold (DI: 9.00) in 1991, Real Quiet (DI 5.29) in 1998, and Charismatic (DI: 5.22) in 1999. It happened again in 2005 when Giacomo (DI: 4.33) won the Derby.
For a complete explanation of the Roman system of dosage, you can visit Dr. Steven Roman's website at www.chef-de-race.com.
Should breeders use dosage to plan matings?
This is a question we are often asked. The answer is a qualified no. Does it really matter whether you win the Breeders' Cup Sprint or the Breeders' Cup Classic? Of course, there is more money and prestige with the Classic, but isn't the idea to breed a top stakes-caliber racehorse, regardless of how far it can go? Roman's Dosage was never meant to be used to select the best stallion for a particular mare.
Nevertheless, if a breeder has a mare with a stamina-laden pedigree, a stallion should be selected who adds some speed to a prospective foal's pedigree, and visa versa. To this extent, dosage can be useful in mating decisions.