American Thoroughbred

Understanding Sprinting Thoroughbred Lines
in Sport Horses

Domino- the all American Sprinter

Americans, stop being ashamed of your Thoroughbred horses! This article is meant to help you understand the sprinting lines in the American Thoroughbred, so you will no longer have to worry about them, and maybe use them to your advantage in creating the perfect sport horse.

At Warmblood and Sport Horse inspections, they are judging your horse upon its conformation, way of moving and pedigree: this is how they determine its suitability for sport or breeding. If your horse, whether a full Thoroughbred or not, is built "downhill" or has a straight shoulder,it is going to be judged negatively. And in case you haven't noticed (although this might have changed by now), there is an overall less than positive regard for the American Thoroughbred. We have all been told that the American Thoroughbred is too speed oriented and therefore unsuitable for Olympic style sports.

Is the American Thoroughbred too speed oriented? Yes and no. In America (and in many other countries) racehorses have been selectively bred for the fast maturing brilliant types. It is all about money- if the two year old wins, they get an early return on their investment. Keep in mind, that not all American Thoroughbreds are bred this way and America has staying bloodlines. Many of these sprinters do not train on well, they lack the stamina to succeed at the classics- they are true sprinters. Sprinters tend to be built downhill and have a straight shoulder, and that conformation works against them for Olympic type sports that require extension,collection and stamina.

That said I have a few surprises for you that may change your thinking about your Thoroughbred horse and the American Thoroughbred in general. Remember always that without the Thoroughbred contribution, that there is no sport horse. The importance of the Thoroughbred in Sport Horse breeding. And if you understand how something works you can use it to your advantage.

Breeding Principle: The Thoroughbred pedigree researchers determined that speed can be built into a horse by duplicating 3/4 siblings close up, and that both speed and class by duplicating full siblings close up. The speed making duplicated individuals are usually stayers, not sprinters! They found that stamina is built by multiple duplications in the 6th through 10th generation. They also found that failure to revisit the stamina background strength closer up, that is funneling it in the 4th through 6th generations can cause dissipation of the talent developed in the far reaches (Harper). More on Pedigree Generation Position

Stamina Lines in the American Thoroughbred

So, what is the story here? Let's examine the sprinting Thoroughbred and what it is made of, and I think you will be a little surprised. The great equine scholar, Alexander MacKay-Smith traced the speed influences in Thoroughbreds in his "Speed and the Thoroughbred"- an excellent work. He stated that the sprinting lines in the modern Thoroughbred all originate at 6 sources. I say a thank you to Mr. Mackay-Smith, and present them here for you to understand, they are:

St. Simon- a true wonder horse, born in 1881 in England, and some say he is the most successful sire ever. I don't think I have ever seen a modern Thoroughbred pedigree where he is not represented multiple times. He was unbeaten as a racehorse, although he wasn't raced until after he was 3. He is pre-potent for speed, at all distances.. That means he produced fast distance horses as well as sprinters.

St. Simon

Domino - born 1891 in America, pre-eminent sprint sire, although his grandsons Celt and Colin were great classic mid-distance winners- the best of their era. Colin beat the stayer Fair Play three times including the Belmont Stakes.

Americus- also born in the USA (1892), but he was shipped to Ireland where he strongly influenced the European Thoroughbred.

The Tetrarch -born in 1911 in England, called the spotted wonder for obvious reasons was unbeaten at 2, and produced the sprint sire: Tetratema and the amazing Mumtaz Mahal called the fastest filly ever. Mumtaz Mahal is out of an Americus dam.

Phalaris- the most predominant sire line today, was born in 1913 in England, was the fastest horse of his day at less than a mile- a pure sprinter. I challenge you to find a good sport horse today, in any country, without a Phalaris line in him! He produced mid-distance horses as well as sprinters. Phalaris is a source of great hind end impulsion, but can also give weak front legs. His ability to transmit great impulsion is seen in the Hanoverian sire Lauries Crusador.

Havresac - born in 1915, a top Italian sire, used by Tesio who probably didn't realize that Havresac was dominant for speed. Tesio avoided sprint lines until late in his career. When he finally let some in he got his world beaters: Nearco and Ribot.

If you are thinking, hey, wait a minute- most of these sprint influences are European; I say good for you, and get ready for some more surprises.

Here is one: MacKay-Smith stated that the high hind quarter we so associate with sprinters comes down the genetic trail from the Godolphin Arabian (a Turkoman/Arabian). Turkoman horses were best at races of 4 to 20 miles. Arabians are still the best at 25 to 100 mile races. Neither were good sprinters.

Here is another: One of the greatest horses of recent times, anywhere, is Secretariat. He won at all distances, on all surfaces, with energy to spare. You certainly couldn't classify him as a sprinter, yet he contains all six of the above Sprint lines.

So, obviously there is more to this then sprint equals sprint.

What do these sprint sources' pedigrees tell us? I found that 4 of the 6 are out of one inbred parent, with the other parent directly engaging that inbreeding. The other two are closely inbred themselves. This is just what the experts told us- that inbreeding to close relatives builds speed.

St.Simon- is by the inbred Galopin, who is 2x2 to the half siblings:Merope and Voltigeur. The dam brought in the full sister to Voltigeur: Velicipede.

Phalaris- is out of inbred Bromus, 1x2 to a son and daughter of Springfield. The sire Polymelus brings in a Hampton line- who is brother to Wenlock who is behind Sainfoin the Springfield son, and he adds a Bend Or line who is a genetic relative to Sunrise, the Springfield daughter. Springfield is 4x4 to the full siblings Pasinquade and Touchstone.

Havresac- his dam Hor Concours is inbred 4x2 to St. Simon and his full sister Angelica. His sire Rabelais brings in another St. Simon line, which makes Havresac 2x3x5 to St. Simon and his full sister.

Domino- His dam, Mannie Grey, is inbred through her dam Lizzie G., who is 2x3 to War Dance/Lecomte, 3/4 brothers. His sire's dam, Hira is 3/4 genetic sister to Lizzie G., which brings together Lexington-Lecomte 3x3x4x4.

Thoroughbred pedigree expert, Floyd Oliver, wrote a fascinating article of the genetics in Domino:

The Breeding Behind Domino

The Tetrarch- creates a close inbreeding himself with Bend Or and his 3/4 sister Rose of York 3x3, plus there is an additional 1/2 sibling to each of these two, 3x3.

Americus- is 2x2 to the full siblings the Nun/Norfolk, by Lexington out of Novice, a Glencoe daughter.

Most of the above lines (with the exception of Springfield) that are closely duplicated are in themselves not sprint lines- this is important- even St. Simon, a producer of speed, also created stayers. For instance, Lexington is an old style stayer but his close duplication creates amazing speed in Americus and Domino.

So there you have the notorious sources of sprint lines in our Thoroughbred. As you can see they are not just an American phenomena, and they can easily be adjusted by proper breeding technique.

Why is this important to Sport Horse breeders? First, we can not avoid these lines, so we better find a way to use them, and Second, we can apply the breeding principle in designing our own pedigrees to our advantage. The sprint lines deliver brilliance, courage and strong hearts, which we can certainly find a use for in our sport product.

It might surprise you to learn that Hanover did this very thing- used a Thoroughbred sprinter as a standing stallion at their state Celle. One of the premier dressage lines in Hanover is Lauries Crusador.

Close inbreeding of staying lines can cause sprinters- this can apply to sport breeders, not just in their Thoroughbred lines, but warn us to be careful on how we inbreed or linebreed the sport line carriers. It is very important that when we closely breed, that the lines we choose are sound, sane and talented. To closely breed in something that is talented, but has a weakness or some unsoundness can flaw our gene pool for generations. Remember always that the influence you concentrate and balance in your pedigree construction will be the most dominant.

Ruffian- a tragedy of close breeding

134th Kentucky Derby- a vivid demonstration of the benefits and the perils of inbreeding.

Mumtaz Mahal- an example of successful close breeding


On the Pedigree Generation Page the experts told us to do our duplications in the engine room- and this is in most cases the way for us to go. For sport breeders, if you loosen up the duplications, use the engine room area and sex balance the multiples, you will get the ability, and the pre-potence, but maybe not the problems we sometimes see in closely inbred horses. Drabant, the grandsire of Flamingo is an example of close inbreeding to male only lines- resulting in a brilliant but "hard to ride" horse.

There is always an exception to the rule and close inbreeding can be carried off when the breeder is knowledgeable and conscientous. Example of a Successful Inbred Sport Horse Stallion- Noteworthy.
And Asher, a successful example of inbreeding to an Elite mare.

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