The Origin of Dosage and What it Means

Plus, how theorists use dosage in conjunction with the Experimental Free Handicap to try to select winners of the Kentucky Derby

by Mary Simon

Dual Qualifiers for 2009

Horse	Exp. Weight	Dosage
Midshipman	126	2.37
Vineyard Haven	124	3.00
Square Eddie	123	3.40
Street Hero	122	3.57
Donativum (GB)	120	1.50
Pioneerof the Nile	120	3.89
Westphalia (Ire)	119	2.40
Coronet of a Baron	118	1.91
I Want Revenge	118	3.00
Terrain	118	2.20
Big Drama	117	3.00
Charitable Man	117	2.06
Believe in Hope	116	3.00
Chocolate Candy	116	2.08
Del Conte	116	1.67
Southern Exchange	116	2.69
West Side Bernie	116	1.80

Non-qualifiers for 2009

Horse	Exp. Weight	Dosage
Old Fashioned	121	5.22
Springside (f)	117	4.33
Beethoven	116	5.86
Run Away and Hide	116	7.00

Qualifying fillies for 2009

Horse	Exp. Weight	Dosage
Stardom Bound	124	3.36
Dream Empress	120	0.92
Laragh	117	2.25
Sky Diva	117	3.33
Doremifasollatido	116	1.22
Mani Bhavan	116	2.27
Maram	116	1.91
Rachel Alexandra	116	1.55
Heart Shaped	115	1.67
Wynning Ride	115	2.00
Dave’s Revenge	114	3.67

Origins of dosage

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 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 in the last century. After studying pedigrees of European classicists, he discovered that while most names appeared only fleetingly, a few stallions 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 (a sire noted for getting top-quality sprinters) to professional (a sire noted for getting horses to run in the top races at long distances), 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, Steven Roman, Ph.D., 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 aptitudinal 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 used today are: Brilliant, Intermediate, Classic, Solid, and Professional—representing extreme speed to extreme stamina.

Dual Qualifiers

The late Leon Rasmussen, a respected student of pedigree and longtime Daily Racing Form columnist, was an enthusiastic follower of dosage. During the early 1980s, he utilized dosage index in conducting an analysis of Kentucky Derby winners since 1929; his study revealed that more often than not, these elite runners had matured early, displayed the highest of quality as juveniles, and were genetically well-suited to withstand pressure over a heart-testing distance of ground, against the best of their generation—every one of them possessed a DI of less than 4.00. On the basis of his research, in 1984 Rasmussen developed the “dual qualifier” system, to highlight key characteristics shared by successful classic runners.

The Experimental Free Handicap, which ranks two-year-olds according to their achievement, was chosen as the standard for indicating early maturity and class; “genetic suitability” would be based on a stamina-infused DI of 4.00 or less. If a horse ranked within ten pounds of the top on the Experimental and possessed an appropriate DI, then he or she would be termed a “dual qualifier.”

Through most of the 1990s, the dual qualifier theory held up quite admirably in determining possible Kentucky Derby winners. In the last ten runnings, however, the concept seemed to implode.

In 1998 and ’99, Derby winners Real Quiet (DI 5.29) and Charismatic (DI 5.22) exceeded the 4.00 guideline, and only Real Quiet was rated on the Experimental Handicap—but his 117-pound assignment was more than ten below that of 1997 Horse of the Year Favorite Trick.

Kentucky Derby winners from 2000 through 2004 all had qualifying dosages, but not one of the five was weighted on the Experimental. These were Fusaichi Pegasus (2000, DI 3.67), Monarchos (’01, DI 1.40), War Emblem (’02, DI 3.40), Funny Cide (’03, DI 1.53), and Smarty Jones (’04, DI 3.40). Their absence from the Experimental appeared to reflect a trend toward fewer two-year-old starts for classic-quality runners, especially in the stakes races necessary to receive Experimental consideration. Both Fusaichi Pegasus and Monarchos were still maidens at the beginning of their three-year-old campaigns.

In 2005, Giacomo reversed that trend, having a sufficiently high Experimental ranking (122), but an over-the-limit DI of 4.33.

The following season, Derby winner Barbaro was, conversely, well-credentialed in terms of DI (1.81), but a 114 Experimental ranking did not put him within ten pounds of the ’05 juvenile leader.

Dual-dosage adherents got a long-awaited shot in the arm in 2007 with the appearance of Street Sense on the classic scene. That spring, the son of Street Cry (Ire) became the first Kentucky Derby winner since Silver Charm in 1997 to have both sufficient dosage (DI 2.14) and Experimental standing (127 highweight) to be a dual-qualifier.

In 2008, Big Brown, who was not weighted on the Experimental, having made only one start at age two, won the Kentucky Derby possessing the correct DI, 1.67.

If Street Cry’s feat of 2007 is to be duplicated in 2009, it will be up to one of 17 dual-qualifying colts and 11 fillies to get the job done. Among them are champion and Experimental highweight Midshipman and champion juvenile filly highweight Stardom Bound, with dosages of 2.37 and 3.36, respectively.

A word of warning

As with almost any man-made tool, caution must be taken when utilizing these theoretical indexes, profiles, and dual qualifying systems. The late author-breeder Abram Hewitt, who embraced dosage, issued a warning long 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.”

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. (Curlin’s DP, for example, is 9-3-8-0-0.)

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 Curlin’s. One would be hard pressed 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 far more likely to find minimal-to-nonexistent influence from the professional end, as with 2007 champions Rags to Riches (8-11-19-0-0) and Curlin.

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 Cigar’s DI of 2.33 indicates he has slightly more stamina in his pedigree than average. A 4.00 DI is generally considered to be the cutoff, beyond which a horse is considered unlikely to successfully negotiate 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), a winner of three 1 1/2-mile Grade/Group 1 events in three countries during the 1990s, had a CD of -.20. Man o’ War apparently could have run all day and into the night with a -1.17 CD. On the other hand, 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 had seen in decades.

Chefs-de-race

BRILLIANT

Abernant, Apalachee, Baldski†, Black Toney†, Blushing Groom (Fr), Bold Ruler†, British Empire, Buckaroo†, *Bull Dog, Carson City†, Cicero *Court Martial, Double Jay, Fair Trial, Fairway, *Gallant Man†, *Grey Dawn II†, Grey Sovereign, Habitat, Halo†, *Heliopolis, Hoist the Flag†, Hyperion†, Icecapade†, In Reality†, Intentionally†, Key to the Mint†, King’s Bishop†, Mr. Prospector†, *My Babu, *Nasrullah, Nearco†, Never Bend†, *Noholme II†, Northern Dancer†, Olympia, Orby, Panorama, Peter Pan, Phalaris, Pharis, Pompey, Raise a Native, Reviewer†, Roman†, Rough’n Tumble†, *Royal Charger, Seattle Slew†, Sharpen Up (GB)†, Sir Cosmo, Speak John†, Spy Song, *Tudor Minstrel, *Turn-to†, Ultimus, Unbridled†, What a Pleasure

INTERMEDIATE

Ack Ack†, A.P. Indy†, Baldski†, Ben Brush, Big Game, Black Toney†, Bold Bidder†, Bold Ruler†, Broad Brush†, Broomstick, Buckaroo†, Caro (Ire)†, Carson City†, Chief’s Crown†, Colorado, Congreve, Damascus†, Danzig†, Djebel, Dr. Fager, Eight Thirty, Equipoise†, Fappiano†, Full Sailm, *Gallant Man†, *Grey Dawn II†, Havresac II, Hoist the Flag†, Indian Ridge, Intentionally†, *Khaled, King Salmon, King’s Bishop†, *Mahmoud†, Nashua†, Native Dancer†, Never Bend†, Petition, Pharos, Pleasant Colony, Polynesian, *Princequillo†, Riverman†, Roman†, Secretariat†, Sir Gaylord†, Sir Ivor†, Speak John†, Star Kingdom†, *Star Shoot, Sweep, The Tetrarch, Tom Fool†, Traghetto, *Turn-to†, T. V. Lark, Unbridled†

CLASSIC

Ack Ack†, *Alibhai, Alydar, A.P. Indy†, Aureole, *Bahram, Best Turn, Blandford, *Blenheim II†, Blue Larkspur, Blushing Groom (Fr)†, Bold Bidder†, Brantome, Broad Brush†, Buckpasser, Bull Lea, Caro (Ire)†, Clarissimus, Count Fleet, Creme dela Creme†, Damascus†, Danzig†, Equipoise†, Exclusive Native, Fappiano†, *Forli, Gainsborough, Graustark†, Gundomar, Hail to Reason, Halo†, *Herbager†, High Top, His Majesty, Hyperion†, In the Wings (GB)†, Icecapade†, In Reality†, Key to the Mint†, Luthier, Lyphard, *Mahmoud†, Midstream, Mill Reef†, Mossborough, Mr. Prospector†, Nashua†, Native Dancer†, Navarro, Nearco†, Never Say Die, Nijinsky II†, Niniski†, *Noholme II†, Northern Dancer†, Nureyev, Persian Gulf, Pilate, Pretense, Prince Bio, Prince Chevalier, Prince John, Prince Rose, Promised Land, Reviewer†, *Ribot†, Riverman†, Roberto, *Rock Sand†, Rough’n Tumble†, Sadler’s Wells†, Seattle Slew†, Secretariat†, Sharpen Up (GB)†, Shirley Heights†, Sicambre, Sideral, *Sir Gallahad III, Sir Gaylord†, Sir Ivor†, Star Kingdom†, Swynford, Ticino†, Tom Fool†, Tom Rolfe†, Tourbillon†, Tracery, *Vaguely Noble†, Vieux Manoir, War Admiral

SOLID

Asterus, Bachelor’s Double, *Ballymoss, *Blenheim II†, Bois Roussel, Busted, Chaucer, Chief’s Crown†, Creme dela Creme†, Discovery, Fair Play†, Graustark†, *Herbager†, In the Wings (GB)†, Man o’ War, Mill Reef†, Nijinsky II†, Oleander, Pia Star, *Princequillo†, Reliance†, Relko, Right Royal, *Rock Sand†, Round Table, Sadler’s Wells†, *Sea-Bird, Stage Door Johnny†, Sunstar, Tantieme, *Teddy, Ticino†, Vatout, *Worden

PROFESSIONAL

Admiral Drake, Alcantara II, Alizier, Alycidon, Bayardo, Bruleur, Chateau Bouscaut, Crepello, Dark Ronald, Donatello II, Ela-Mana-Mou, Fair Play†, Foxbridge, Hurry On, La Farina, *Le Fabuleux, Massine, Mieuxce, Niniski†, *Ortello, Precipitation, Rabelais, Reliance†, *Ribot†, Run the Gantlet, Sardanapale, Shirley Heights†, Solario, Son-in-Law, Spearmint, Stage Door Johnny†, Sunny Boy, Tom Rolfe†, Tourbillon†, *Vaguely Noble†, Vandale, Vatellor, Wild Risk

NOTE: A dagger following a sire’s name indicates he has been placed in two separate aptitudinal classes. Therefore, his influence in any generation is divided equally between those two classes. The sire classifications were made by Steven Roman.