Bloodlines: Size And The Thoroughbred

by | 11.13.2018 | 11:45am
Unbridled's Song

Several times over the past weeks, readers have commented on the look of the contemporary Thoroughbred in comparison with horses of past years. In particular, readers have noted that racers today appear to have lighter bone than the horses of yesteryear who raced so successfully season after season.

From my personal experience in measuring horses over the past decade and a half, I would concur there are differences between horses of today and those of 50 or 60 years past. From that past era, DataTrack has measurements of a sizable minority of horses, typically important racehorses, who were foaled in the 1960s and 1970s, as well as many more from more recent years.

The surprise, I suppose, is the difference in bone is not what an interested observer would expect. The typical circumference of the cannon bone (long bone immediately below the knee in the foreleg) among horses of the 1960s and 1970s ranges from 8 to 8.5 inches. Secretariat, for instance, had a front cannon circumference of 8.25 inches. Northern Dancer was 8 inches, as were Lyphard, Mr. Prospector, and Danzig.

The startling result of the data is the typical cannon circumference today is in the same range.

The difference between horses of a half-century ago and today is not in circumference of the cannon but in its length. Secretariat, Mr. Prospector, and Danzig had front cannons that measured 13.25 inches; Northern Dancer and Lyphard measured 13 inches.

In contrast, the cannon length of quite a number of contemporary horses is a fair bit longer. A significant source of this greater length is the Breeders' Cup Juvenile winner and leading sire Unbridled's Song. A really big, really fast, really dominant son of Kentucky Derby winner Unbridled, Unbridled's Song was an exceptional individual at the 2-year-old in training sales, hammered down for seven figures before being turned back because a vet detected a “flake” in an ankle.

Owner-pinhooker Ernie Paragallo took the colt back and never had a luckier day. Unbridled's Song proved as exceptional on the racetrack as he had been at the sales ring. A Grade 1 winner at 2 and 3, Unbridled's Song promised even more than he proved on the racetrack, and that promise, along with his exceptional presence and visual appeal, earned the big gray a first-rate opportunity at stud on Taylor Made Farm.

In addition to becoming a first-tier sire, Unbridled's Song was the near-contemporary of Storm Cat who vied most with that great sire as a superpower at the sales. Unbridled's Song sired big, scopy stock with good bone. They had a lot of leg and stretch that made them visually impressive, and sales buyers could not help themselves. They bought the stock by Unbridled's Song for big money; from 17 crops by the grand gray son of Unbridled, weanlings, yearlings, and 2-year-olds in training by him sold for more than $296 million.

The Unbridled's Song prospects sold for serious money long after it became clear that, talented as they undoubtedly were, they were less than the soundest racing propositions under contemporary conditions.

The fundamental reason they had trouble staying sound is that they were so talented; slow horses don't put as much pressure on their structure and are less likely to break down.

This conundrum has long been a problem for leading sires because most of them sire stock that perform close to the physical limitations of the strengths of the materials that make up the Thoroughbred racehorse.

To the universal demands of high speed for racing success, Unbridled's Song – and other big sires who tend to sire tall, strongly made horses – added the extra challenge of those long legs, and the sales buyers – who direct the breeding of horses to a great extent and have done so for 30 years or more – love to pay big money for tall, strongly built, athletic-looking young horses.

In contrast to the stallions of 50 years ago who would have cannon lengths of 13.25 inches or so, stallions today frequently have cannon bones an inch or more longer. Surely, that doesn't make all the difference? Generally, not by itself.

The radius (bone immediately above the knee) is also longer, however, and the horses' bodies are correspondingly lengthier and taller. With the extra bone and muscle, these brave new horses are also heavier. The extra weight, multiplied by the force of racing at high speed, pushes them ever closer to the structural limits of bone and sinew, and that's the final problem for racing Thoroughbreds and keeping them sound and happy.

So, to encourage the breeding and use of horses that race often and effectively, I would propose the development of racing programs that reward horses for winning races, rather than so disproportionately rewarding those lucky enough to win the 3 percent of stakes races.

This sort of program would be 1) good for the breed because even horses who were a step off stakes quality would reward their owners, 2) good for breeders because their horses would be in greater demand and able to earn more, 3) good for the sales because increased rewards at the track would encourage a much deeper pool of buyers, and 4) good for the racetracks because there would be a more robust pool of racehorses to fill their cards and engender greater handle and more bettor enthusiasm.

Racing more often in a program such as this would help to return the breed to a greater functionality, thus enlivening the sport at every level and guaranteeing the positive progress of the Thoroughbred in the 21st century.

Frank Mitchell is author of Racehorse Breeding Theories, as well as the book Great Breeders and Their Methods: The Hancocks. In addition to writing the column “Sires and Dams” in Daily Racing Form for nearly 15 years, he has contributed articles to Thoroughbred Daily News, Thoroughbred Times, Thoroughbred Record, International Thoroughbred, and other major publications. In addition, Frank is chief of biomechanics for DataTrack International and is a hands-on caretaker of his own broodmares and foals in Central Kentucky. Check out Frank's lively Bloodstock in the Bluegrass blog.

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