How Race Winners Are Bred | Horse Pedigree & Bloodlines

Horse Racing bettors often take a huge interest in the pedigree of horses as this can provide an insight to likely race winners.

The “thoroughbred” is a breed best known known for agility, speed and spirit; all suitable characteristics for horse racing. Thoroughbreds are recognised as distance runners or sprinters, and their form usually reflects what they have been bred to do.


The Size of Horses

When choosing a potential racehorse its size is a big consideration. Sprinters are generally well muscled, while stayers or distance runners, tend to be smaller and slimmer.

Although there have been champion racehorses of every height, the best racehorses tend to be of average size. This is partly due to the fact that larger horses mature more slowly and have more stress on their legs and feet. This predisposes them to lameness. The smaller horses are also considered to be at a disadvantage due to their shorter stride and tendency of getting bumped by other horses — especially in the starting gate.

Historically, thoroughbreds have steadily increased in size. The average height of a Thoroughbred in 1700 was about 13.3 hands high. By 1876 this had increased to 15.3. The average height of today’s thoroughbred is a little over 16 hands.


The X-Chromosome

Pedigree records of bloodlines and race results go back generations. Believers in the Pedigree are convinced that disposition is strongly influenced by the X-chromosome.

In recent years there’s been studies about the X-chromosome, citing the inheritance of a large heart as a feature of distinction. Indeed the large heart influences a horse’s growth and development, strength, stamina, endurance, and longevity; traits not only applicable to racing, but to a healthy life in general. Many large-hearted horses live long lives, to 30 or beyond.

Studies reveal that intelligence is carried on the X-chromosome. What this means for a performance horse breeder is that they can observe the dams (mothers) of stallions and identify those with genetics suited for the races they are targeting. The traits they are seek may be located on the female side of the pedigree. Merely observing the bloodline represents a traditional and somewhat dated approach to breeding a winning horse. Nowadays examining the DNA of horses to find good breeding stock is becoming common practice.


Modern Approaches To Breeding Winners

Delving back too far in the pedigree becomes of limited value to breeding winning horses. Relying solely on this approach is dangerous, since it can be a poor guide to quality. After all, an ancestor five generations back contributes only 3% of an animal’s DNA today.

The Green Monkey Racehorse is an example of the dangers of relying on bloodlines. In 2006 a two-year-old colt with an impeccable pedigree sold at auction for $16m. At the time, this was the highest price of a publicly auctioned thoroughbred. It ran just four times and failed to win once.

But could the buyer have known better?

The industry continues to improve, and today it is believed that focusing solely on what the direct parents achieved is of most significance and it improves the chances of success. Breeders can also take things a step further and find out more information about the parents’ DNA; for thoroughbreds this is studied in great depth.

Companies such as Genetics Limited, founded in 2000, create genetic profiles of horses. They were the first in the world to offer DNA screening for racehorse performance. Over the last decade the profiling has helped to identify markers linked to equine stamina, strength, respiratory system and energy use. It is said that these techniques are 75% better than conventional non-genetic methods for selecting potential winners from a group of horses. The tests indicate whether or not a horse is best suited as a sprinter, a long-distance athlete or something in between.

Tests can also reveal the level of inbreeding in a horse. Sometimes a degree of inbreeding, which is often associated with health problems, can be beneficial to race horses. Breeders often use a form of inbreeding called “line-breeding” — a process where horses are bred to reproduce qualities more than once in their pedigree. The intention is to create other horses with features as similar as possible to the exceptional ones identified, by narrowing the pedigree to a few closely related lines of descent. It reduces variability. Line-breeding has produced many beautiful, athletic and exceptionally talented horses.

Close breedings not only bring out the good and desirable traits in a horse, but also some of the worst traits which might have been lying hidden for generations. This is the weakness of inbreeding and linebreeding — it sometimes produces an extreme, rare case. It is so important to research as much as possible about a certain stallion for example, to whom you are breeding the related mare.

Aside from genetics & DNA, other elements still play a huge part on the race day. The training, nutrition, jockey and track conditions remain of great importance. Geneticists estimate that DNA accounts for only 30-35% of a horse’s performance; so trainers are increasingly turning to experts specialising in gait and lameness. Patterns have indeed proved useful in spotting the causes of lameness and it’s now known, for example, that Racehorses put extraordinary pressures on their legs and muscles when galloping and each limb has to support the equivalent of two and half times the animal’s body weight. In a 500kg animal, that’s 1.25 tonnes with every stride. This kind of analysis helps to improve the performance and longevity of Racehorses regardless of their genetics. In many ways such studies are equivalent to sport scientists with the objective of pushing the healthy human anatomy to it’s limits during exercise.


Applications Of ‘The Pedigree’ To Betting

The pedigree tells us a horse’s capability based on its genetics. But often very little is known about the performance of horses in maiden races, or horses debuting on a new surface. Markets tend to form odds based on on public news, gossip or speculation; there’s not there’s not much focus on the bloodline.

Historically there’s a huge difference between the high achievements of the offspring of good and the comparatively low achievements of mediocre sires. Therefore if you know nothing more about an unraced (or lightly-raced horse) than the identity of its sire you would already know something of worth.

Admittedly, pedigree data can be overwhelming and as a result horse racing fans shy away from using it altogether. But remember: the more effort your betting system takes, the less more chance you have of finding that competitive advantage.

You can find horse pedigree data from:


Interesting Facts About Racehorses

  • Statistically, fewer than 50% of all race horses ever win a race. Less than 1% ever win a stakes race such as the Epsom Derby.
  • A horse who hasn’t yet won a race is known as a “maiden”
  • Horses that retire from a racing career and are not suitable for breeding purposes often become riding horses or other equine companions. Agencies exist to help make the transition from the racetrack to another career, or to help find retirement homes for ex-racehorses.


Further Reading:

The Impact of Weather On Horse Racing (The “Going”)

Toby @ Punter2Pro
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ed pierce
ed pierce
6 years ago

I have heard from a lot of punters that science can’t accurately predict a good horse those are usually the people betting and losing. The science of choosing a good horse makes sense and it is backed up by facts that can’t be ignored. I will always look at a horse this way, especially if I am putting my money on it.

Reply to  ed pierce
6 years ago

More and more bettors are starting to look at Pedigree as a way of predicting races. Obviously if everyone did this then the odds begin to reflect the chance of the horse winning, and it’s worthless. However, i think that there are special cases where, for example, the horse isn’t experienced but has a particularly good bloodline. This type of scenario is an area that can definitely be explored for opportunities.