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DOSAGE PAST AND PRESENT

For years, dosage has represented one of the most popular methods of pedigree evaluation. In brief terms, it calculates a horse’s distance potential based on certain stallions that show up in the first four generations of his pedigree. Although not universally embraced, the ideas behind dosage have long fascinated students of bloodlines.

Lt. Colonel J. J. Vuillier first came up with the concept of “dosage” early last century. After studying pedigrees of European classicists, he discovered that while most names appeared only fleetingly, a few stallions (and one mare, Pocahontas) showed up repeatedly. These influential individuals would eventually be referred to as “chefs-de-race”-”chiefs of the breed.” Vuillier thereafter centered his analysis around the percentage of genetic influence of those elite few on a pedigree.

Dr. Francesco Varola subsequently added “aptitudinal analysis” to the concept-that is, he considered what characteristics given chefs tended to contribute to the breed. From this, he created aptitudinal classes, ranging from brilliant to professional, in which he categorized each chef-de-race. By figuring the number of chefs in a pedigree that fell into each category, Varola developed individualized “dosage diagrams.” Calculations were made over an unspecified number of generations, each of which was given equal weight.

Beginning in the 1970s, Dr. Steven Roman refined dosage further. He limited analysis to the first four generations, based on Galton’s Law-the premise that the closer up an individual is in a pedigree, the more influence that individual will have. Accordingly, Roman assigned point values to the chefs, dependent upon in what generation they occurred. First generation chefs were allotted 16 points; second generation, eight points; third, four points; and fourth, two points. If a stallion fell in two categories (as many do in Roman’s system), the points were evenly split.

Roman also transformed Varola’s aptitudinal classes, eliminating “transbrilliant” and “rough,” and redefined the categories in terms of relative stamina, a concept not in keeping with Varola’s patented model. The categories widely used today are: brilliant, intermediate, classic, solid, and professional-representing extreme speed to extreme stamina.

Dosage profile

A Roman dosage profile (DP) is derived from the points of chefs found in four generations of a pedigree and where they fall on the aptitudinal chart. Fusaichi Pegasus’s DP, for example, is 22-10-24-0-0.

Since breeding has changed in the last century to emphasize speed over stamina (particularly in America), modern pedigrees are likely to lean toward brilliant-to-classic, as does that of Fusaichi Pegasus. One would be hard pressed today to find top runners without at least some brilliant or intermediate influence in their pedigrees-as was the case with Man o’ War (0-0-4-12-8) and 1930s champions Discovery (0-0-0-4-6), Gallant Fox (0-0-16-8-4), and Challedon (0-0-16-4-2). Presently, the reverse is true: one is more likely to find minimal-to-nonexistent influence from the professional end, as with 1999 Horse of the Year Charismatic (9-10-9-0-0), Lemon Drop Kid (13-4-21-0-0), and leading sire Storm Cat (11-8-10-1-0).

Dosage index

The dosage index (DI) is derived from the profile to reflect the ratio of speed-to-stamina in a pedigree. This is calculated by adding points from the two “speed” categories (brilliant and intermediate) plus half of those from the classic (middle) category, and dividing that total by the points from the two stamina categories (solid and professional), plus the other half of the classic points. The higher the DI, the more speed is supposedly present in the pedigree.

Average North American DI is 2.40-thus, Fusaichi Pegsus’s DI of 3.67 indicates he has somewhat less stamina in his pedigree than average. A 4.00 DI is generally the cutoff, over which a horse is considered not likely to get the American classic distance of 1 1/4 miles.

Center of distribution

Center of distribution (CD) is a more complicated calculation derived from the profile. Theoretically, as with DI, the higher the CD, the lower a horse’s distance potential. Average CD in this country is +.70. Apple Tree (Fr)-winner of three 1 1/2-mile Grade/Group 1 events in three countries in 1993-’94-had a CD of -.20. Man o’ War apparently could have run all day and into the night with a -1.17 CD. Conversely, Secretariat’s CD of +.90 was above average-yet he was arguably the most eminently capable runner at up to 1 1/2 miles that this country has seen in years.

As with almost any man-made, theoretical tool, caution must be taken. The late author/ breeder Abram Hewitt, who embraced dosage, issued a warning years ago when he wrote: “By definition, dosage studies are restricted to ‘chefs-de-race,’ and all other mares and sires are excluded from consideration. Some of these exclusions may play an important part in the inheritance of an animal ... and excluding them could prove in some cases misleading. To this extent, handling dosage becomes as much an art as it does a science.”

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