Part II - Thoroughbred and Soundness

This second study on durability and soundness centers on the Thoroughbred. It was launched to investigate not only the bloodlines that seem to promote these much needed qualities in the breed, but to find common root carriers of resiliency between the breeds of Standardbred, American Thoroughbred and Quarter Horse because they were all the same breed until the 1800s. The Thoroughbred has traditionally been looked to as the chief component in sport horse breeding, for its ability to transmit speed, agility, courage, overall athleticism on much less sporty breeds. The modern racing Thoroughbred has soundness problems (as do the warmbloods and other sport breeds) and many riders and breeders are unsure how to pick out a good Thoroughbred for non-racing sport or for their herd improvements.

[Pan Zareta 1911, she started in 151 races and won 76 in her short 6 year career--she died of pneumonia in her stall at the track at age 9.]

Often you will find that non-raced stock is looked upon as more 'sound', the implication being if it has not been put through a race career it has not been damaged, and therefore will be able to stand up well to the new sport challenges. That may be the case, but more often it is not. You must look to the reason it was un-raced, for in an industry that produces horses primarily to race, an unraced horse is often a cull because there is a problem.

When Laura Holmes at Canter USA, Texas branch, wrote the insightful article: "Racehorse Reality Check: Do Numbers Matter? she addressed the false perception that long campaigners are unsound or not suited for second careers. In speaking especially about those horses that have run over 50 races she says:

"Everybody admires their durability, yet few want to take a chance on buying them. It's a sad misconception that these horses are physically used up, when in reality they have proven over and over that they have the brains and body to stand up to the most physcially and mentally demanding discipline. Not only must their bodies be sound, but their minds must be as well. They are almost always classy, intelligent horses who are well respected by those on the backside."

A horse that can stand up for years of racing or competition and/or run in hundreds of races has something valuable to teach us. The task of isolating the key bloodlines in the Thoroughbred were not as straight forward as in the previous Standardbred study (part 1) which had multiple current horses winning over 100 races and a few bloodlines clearly emphasized (further along I will provide a clue coming from a new science study for why this may be so). For whatever reasons, the Thoroughbred has notably fewer centurions than the Standardbreds, although with the help of Robert Flieger I did locate one horse that can rightfully be added to those who have won over 100 starts. I enlisted the help of the facebook group Bloodlines of the Sport of Kings to find durability specimens in the modern Thoroughbred, and got several examples you will see here from their contributions. So a big thanks to Tony Byles, Robert Flieger, Lou Flieger, Michael Felts, Juianna Ochs, Tamara Ault, and Yvelle Eve Hirsch for your important suggestions.

With steeplechasers, it is often a three or four mile course with fixed jumps, an extreme testing, which of itself shows great soundness and durability...only the toughest horses are successful in it. The horses in this study have birth dates from 1830 to 2004, so we have a much longer range then the previous exercise, which may give us an advantage in finding clues on root bloodlines.

[Whisker 1812, he is the sire of the two earliest durability stars on the list: Catherina and Jorrocks, and his line and that of his full siblings: Whalebone, Web, Wire, Woful, Wilful etc. are found as one of the critical mass influences behind a good number of the sound horses in this study. These full siblings are found more often than not in multiples in the English Thoroughbred; Whisker and Whalebone were Derby winners, and their sister Web is the dam of the prolific Glencoe so they are seen more often than the others.]

In the durability group, five are mares and three are stallions, the rest geldings. The only horse that won over 100 races is Galgo Jr. and he won 136 out of his 158 starts. A dozen of the horses actually ran 100 races or over, in order of amount: Bankrupt 348, Sir Prize Birthday 206, Time to Bid 179, Catherina 176, Imp 171, Galgo Jr. 158, Pan Zareta 151, Kingston 138, Mustard 131, Boston RH 112 (heat races-adjusted), Red Rum 110 (steeplechaser) and Exterminator 100. All included in the review exhibited extraordinary soundness and  durability in their careers, some with breathtaking talent, such as Kincsem who won all her 54 starts.

As we did in the Standardbred section, I will list the horses with name/date of birth (dob) and country, chief dominance, and secondary dominance in parenthesis, followed by closest inbreeding-linebreeding. Some of the entries will be dominant in certain bloodlines because of a strong configuration and closeness to the front of the pedigree, others will be by critical mass (see Understanding Pedigrees).

[Note: RH after a few of the racers indicates the pre-Thoroughbred breed in America. The American Thoroughbred came into being in 1868 (accepted the classic race performance test and fulfilled the pedigree requirements of the General Stud Book of the day], any horse before 1868 in America, unless it is full English Thoroughbred, like Sir Archy for instance, is a American Running Horse whether it has some English Thoroughbred lines or not. (See Legacy of Lexington or American Breed Development for more information on the American racer).

[Spendthrift 1876, a new American Thoroughbred, is the sire of two that made our list: Bankrupt who ran more races than any other; 348, and Kingston who raced 138 races. Spendthrift had three full stallion brothers: Rutherford, Miser and Fellowcraft. Spendthrift is the sire of Hastings, who is the sire of Fair Play, who himself is the main influence in Time To Bid (below), and he is the sire of Man O'War and the grandsire of Discovery...all three are chefs de race for stamina, and also a major jump line in the USA. Fellowcraft is the damsire of the mighty Hamburg, a great stayer. Only two horses have won staying races by 100 lengths: Man O' War and Hamburg--that is a clue. The chef de race Discovery is the damsire of both Bold Ruler and Native Dancer and Discovery has Fellowcraft/Spendthrift 4x5 sex-balanced. Fellowcraft holds the world record for 4-mile heat racing, beating his grandsire Lexington's record by a 1/4 of a second.]

Durable and Sound Thoroughbreds

name/dob   race record   1st dominance   2nd dominance   closest inbreeding

Catherina 1830 (GB) 176 starts/78 wins  Snap  (Herod-Highflyer, Sir Peter, Eclipse) 3x3x4

Jorrocks 1833 (Australia)  95 starts/ 65 wins   Trumpator  (Herod, Eclipse, Snap, Partner)  1x6, 2x6

Boston RH 1833 (USA)  112 starts/80 wins  Diomed  (Wildair Mare, Regulus, Eclipse, Fearnought)  3x3

Fashion RH 1837 (USA) 90 starts/65 wins  Sir Archy  (Herod) 3x3

Planet RH 1855 (USA) 77starts/54 wins  Sir Archy  (Herod, Whisker, Diomed, Eclipse) 5x4x4

Harry Bassett RH 1868 (USA) 90 starts/46 wins   Herod  (Eclipse, Highflyer, Comus, Sir Archy)  5x4

Kincsem 1874 (Hungary) 54 starts/54 wins Slane  (Herod-Highflyer, Eclipse, Whalebone, Sir Peter, Camel)  3x4

Bankrupt 1883 (USA)  348 starts/89 wins  Whalebone et al (Herod-Highflyer, Eclipse-Melbourne)  4x4

Kingston 1884 (USA)  138 starts/89 wins Whalebone et al (Melbourne, Herod, Eclipse, Glencoe, Touchstone) 4x4

Imp 1894 (USA)  171 starts/62 wins  Stockwell/Rataplan  (Lexington RH, Orville)  4x4x5

Pan Zareta 1911 (USA)  151 starts/76 wins  Bonnie Scotland  (Birdcatcher, Glencoe, Lexington RH, Boston RH)  4x4

Exterminator 1915 (USA)  100 starts/50 wins  Blair Athol/Blinkhoolie  (Stockwell/Rataplan, Vededa/Que Vive, Newminster)  5x5x5

Galgo Jr 1927  (Puerto Rico)  158 starts/136 wins  Galopin  (Touchstone, Pocahontas, St. Simon-Newminster)  6x6x4x6

Camareo 1951  (Puerto Rico)  76 starts/73 wins  Cyllene  (Stockwell, St.Simon, Newminster, Bridget-Meta, Birdcatcher/Faugh-a-Ballah) 6x4x4

Arkle 1957 (Ireland) steeplechase  35 starts/27 wins  Dark Ronald  (St. Simon, Cyllene, Stockwell, Touchstone) 4x4

Red Rum 1965  (Ireland) steeplechase  110/26 wins flat and jumps  St. Simon/Angelica--Fairway/Pharos (equal potency) (Polymelus, Cyllene, Newminster, Tadcaster, Scapa Flow, Bona Vista) 4x4

Time to Bid 1975 (USA)  179 starts/50 wins  Fair Play  (Sweep--St. Simon, Galopin)  5x5x6, 5x6, 5x6

John Henry 1975  (USA)  83 starts/ 39 wins  Bull Dog/Sir Gallahad  (Whalebone et al, Blue Larkspur-Black Toney, Plucky Liege, Teddy)  4x4x5

Sir Prize Birthday 1980  (USA) 206 starts/39 wins Nearco-St.Simon (Mumtaz Begin, Blandford, Galopin)  4x6

Mustard 1997  (Australia)  131 starts/17 wins  Princequillo  (Nearco-Nasrullah-Native Dancer, Phalaris)  6x6x5, 5x6

Hurricane Fly 2004 (Ireland) steeplechase  41 starts/26 wins  Zeddaan  (Nearco, Vimy) 5x4

Base Stock

As you can see in the above chart, the earliest main dominance is Snap, and this line appears in many others. I will enlarge on the first four entries' main potencies: Snap, Trumpator, Diomed, Sir Archy and see what we come up with for roots. And then see if these identified bases stay dominant in the later stars of resiliency. 

[Kincsem 1874, a Hungarian bred Thoroughbred has to be rated as one of the more remarkable racers ever, not just because she raced 54 times, but because she won all 54!!]

Another issue is when did the Thoroughbred come into being? I prefer to go with Spanker 1690 as the first true Thoroughbred because he was the first to win the new performance test for racehorses that King Charles set out with rules: 4-mile heat racing to test and improve their racers. Others prefer to use the sireline requirement of one of three foundation sires: Darley Arabian 1700, Godolphin Arabian 1724 and Byerley Turk 1680...but are the real foundations? The first oriental to set a type on this tribe of racers was Fairfax Moroccan Barb imported in 1633. I see the big three instead as typesetters on the already established Barb-Running horse base.

Darley Arabian, was not an Arabian, instead believed to be a Barb or Turk, imported 1700. 

Godolphin Arabian, not an Arabian, and he also is believed to be a Turk or a Barb, imported 1724.

Byerley Turk 1680 (I published here in my books my understanding at the time that this horse was not a Turk, but a domestic bred, since that time I have discovered the expert I followed was not correct in this) Thanks to James Hardiman ( I now have it straight. First he believes this horse is the same horse as Duke of Rutland's Blacklegs and Old Leicester Turk) and that he is indeed a Turk and was imported in 1680. If you are having trouble sorting out old English bloodlines, both gallopers and trotters, I recommend you visit James' work posted on, go to the 'highflyer' tab. He had done amazing work in solving many mysteries in the old lines. 

Spanker 1690 was domestically bred by the same Yellow Turk (full Barb, aka Dodsworth, Old Chestnut Turk), out of Old Morocco Mare (aka Old Peg), a domestically bred mare by Old Morocco Barb out of Old Bald Peg, a Hobby-Running Horse dam.

Now is a good time to discuss the DNA study done on the origins of the modern sires because her work reveals some traditional breed labels are incorrect: Dr. Barbara Wallner: "Y Chromosome Uncovers the Recent Oriental Origin of Modern Stallions" where we can get some light shed on these foundation sires. In June 2017 Dr. Wallner and her team published their work on the Y chromosome in the modern horse. They used 52 horses from 21 breeds to get a wide spread view of the Y chromosome. It revealed some surprising results. First, it appears that all domestic horses descend from one stallion about 5500 years ago (did someone mention Noah's Ark?), and that more recently, only about 700 years ago that all breeds descended from one of two major subclades of that chromosome, which they broke down to a Arabian subclade and a Turkoman subclade. They found the Arabian was the sireline in the Barogue breeds (those with an elevated front action), such as the Lippizan, Barb and Arabian plus in draft and pony breeds. And the rest all descend from the Turkoman subclade, identified as the 'Tb' with variants added such as TbDw (Quarter Horse) or TbDm (Standardbred) and others. The scientists surmised the Turkoman branch had fanned out to the majority of breeds via the Thoroughbred. There is also an Iberian subclade that they appear to bunch with the Arabian, and is identified with 'S' or 'L'.

Now, what I found interesting is that there is no 'Tb' subclade in the Barb, as I had assumed that the early imports into Britian were Barb rather than Arabian. The Barb instead falls into the Arabian subclade, but that is doubly puzzling to me because the Barb has existed since 1000 BC on the northern African coast (Phoenician colony) and the Arabian only since 600 AD, so how does a recent breed become the sireline of a ancient breed? (This controversy was cleared up for me by the work of Hylke Hettima, who has spend years investigating the Arabian myths and histories, particularly in relation to the Arab Horse --see The Arabian Myth).

The team determined that all the Oriental stallions that made a mark on the sireline of the Thoroughbred were of Turkoman origin. I personally don't have much trouble accepting that as I always thought the Godolphin was a Turkoman and thought that maybe the Darley was, but it appears the Tripoli Barb was a Turk as well. The report concluded that this confusion in breed origins happened because of "inability of European horse traders in the Oriental horse markets in the 19th century to accurately identify 'purebred' Arabian stallions."

So then, Yellow Turk, a son of the Tripoli Barb out of an imported mare: Lawsons Barb Mare, and so is a domestically bred Oriental. Is he a full Turk or a Turk-Barb cross? There are still some wrinkles in all this that need to be ironed out. We should have guessed about the Yellow Turk just because of his name, the Turkoman and its descendant breed: Akhal Teke are renowned for their lovely metallic golden coat. According to MacKay-Smith in Speed and the Thoroughbred, it was a first rate racehorse up to 25 miles, lots of stamina, a tall, elegant horse, with a longish back and had the ability to pace. 

Spanker 1670 was by the Yellow Turk out of Old Moroccan Mare who was by the imported Moroccan Barb out of Bald Peg 1635, who long was said to be by an Arabian, but the truth is she is mostly Hobby...note her date of birth, just 2 years after the first 'Barb' was is nearly impossible she was bred by an Oriental. (see the work of James Hardiman on for clearing up a lot of the early lineages.)

It is clear from the earliest pedigrees that the Thoroughbred was based on mares from the old Running Horse-Hobby studs (Helmsley, Sedbury, Darcy etc) and often bred to Oriental or 1/2 Oriental stallions...No Arabians in the early foundations, no matter their name. Many of the early lines have unrecorded parentage, often they are listed with an individual ancestor having an oriental name (Arabian or Barb or Turk added), but with no parentage information of that supposed oriental source, no ancestry or whether imported or St.Victors parentage. Work on the old stock bloodlines is continuing in our day. I recommend (if you are interested in the foundations) that you visit and use it as a resource.

[English Hobby (Running Horse), etching from pen and ink drawing done in 1663 by F. Barlow, when this breed was being eradicated in the British Isles...original in the British Museum.]

In the current era of DNA testing many of the supposed imported Orientals are instead found to be domestically bred. The stud book may have become loaded with bogus Orientals because it became a requirement that the entries descend from imported stock--on both sides of the pedigree--not just sireline, and with what we now today about the speed gene coming from the small and gaited Running Horse-Hobby stock, then very many of the native horses may have been mislabeled as well. This happened in America also about a century later when the race entry requirements changed to insisting descent from imported Thoroughbred stock, and all of a sudden 'Thoroughbred' parentage was attached to many fast racers, and their Running Horse ancestry erased (see North American Sport Horse Breeder for a list of known pedigree frauds).

[Historical notes; Before there was a Thoroughbred or any Oriental imported into the British Isles there was the Celtic Horse, local populations called Irish Hobby and English Running Horse. These were gaited, small, fast, docile, stamina loaded saddle-race horses, brought to the British Isles as early as 700 BC, arriving on the Phoenician ships to exchange for the tin mined in the islands. Several waves of the Celts themselves colonized the islands at the same time.

The Irish Hobby was bred in Ireland for 2000 years with little corruption from other breeds; the English Hobby (Running Horse) suffered more dilution from Saxon, Norman and other imports to Britain, which may explain the Irish Hobby was recognized as the faster of the two in the 1500s. King Henry the 8th was having the Irish Hobby imported into his stud for this reason. 

[King Henry VIII on one of the pacing Irish Hobbies he brought into his stud]

These small, gaited, race-saddle horses carried the speed and athletic ability that made the future Thoroughbred possible, and it also became the root stock for the Connemara and Irish Draught, both sport breeds, and surprisingly the horse of the American colonies and the breeds that developed there (received multiple shipments between 1611-1666, before most Oriental was added to the mix). The English Civil war saw most of the racing studs sacked and destroyed (and King Charles executed) by the winning opposition regime. The 'royal studs' of King Charles were seen as something to be wiped out, and this purge resulted in the loss of the Hobby and Running Horse by the end of the 17th century in the British Isles. The future of the Thoroughbred was secured when a remaining remnant was saved by John Darcy and his wife Elizabeth (her dowry was the Sedbury Stud), when they gathered the survivors of the previous race breed into their own studs. If they had not done this there would be no Thoroughbred racehorse, because those small horses carried the speed (see MacKay-Smith's Speed and the Thoroughbred and the speed gene studies by Hill 2012 and Bower 2010).

The Celtic Horse originated in the northern Iberian Peninsula, by 700 BC, a (Spanish Horse on the southern Iberian Peninsula and the Barb of North Africa were earlier established about 1000 BC). The Celtic Horse was gaited and moved with lower motion than its cousins who both had an elevated trotting action. All three populations of horse resulted from the planting of colonies by the Phoenicians and the establishing of the horse of the Anatolia region in those settlements. Anatolia, modern day Turkey, was also the ancestral home of the Akhal Teke and its ancestors. Which would mean that when the much later Turkomans were brought to the British Isles in the 16th century, 2000 years after their ancestors arrived, a deep nick must have occurred when the long separated related breeds were re-united.]

What did the Barb and the Turk do for the breed? The Duke of Newcastle in the 1600s spoke out on what the addition of these Orientals brought to the mix. He said the Barb was "intemperate" which I take to mean 'high strung', and he said it was not as strong as other breeds but still very noble in character and brave. He continued: "The Barb possessed a superb and high action, is an excellent trotter and galloper, and very active in motion." On the attributes of the Turk he said: "The Turk stands high, though unusual shape, being remarkably beautiful and active, with plenty of power, and excellent wind." That translates to me that the Barb gave an excitable nature, bravery, flashy movement rather than fast and a good trot and gallop, possibly having the gait-keeper gene because it was described as a 'trotter' which could mean it could hold the trot at speed. And that the Turk brought size---height, beauty, strength and vast stamina, along with a high movement.

Other breeds crept into the stud book, for instance a cart horse (precursor to the Shire) was the dam sire of Snake Mare 1713, and from her spread throughout the stud book, through such famous lines as Sampson, and through his descendants to such famed horses as Orville with 4 lines of this cart horse, and his son Emilius. Sampson is the sire of Engineer from whom Mambrino and Messenger descend, great carriage horse sires, and also the sire of Cantatrice, the dam of Termagant, the dam of Evelina (dam of notable lines: Cervantes, Orville/Orvillina, Paulowitz). Sampson's 3rd dam is Snake Mare was 1/4 draft. That same Snake Mare had other offspring: Chedsworth Mare, Fox-Hunter Mare, Skim, Sister to Skim, Hip Mare (dam of Sampson) and Old Standard. Just to give you an idea of how this trait multiplied, let me give you a few of the lines from Snake Mare you may recognize. From Fox-Hunter Mare is Giantess (is it a fair guess that this mare inherited the draft mass?) and her daughter Y Giantess (by Diomed) who in-turn is dam of Cressida, Eleanor, Julia Walton Mare, Annabel and Rebecca. For an example of the spread of the line through the generations we can look to the great La Trioenne who carries 40 lines of Young Giantess. From Eleanor we have Muley, from Julia we have Phantom, the sire of Voltaire and from Rebecca we have the enduring jump line of Thormanby. Old Standard is the sire of Hamilton's Figure, the grandsire of Figure 1757, the sire of Don Carlos and others.

[Famous 4-mile heat race between Peytona, a daughter of Leviathan, a son of Muley, who has 2 draft lines via Sampson and Giantess, and Fashion RH who is one of our durability subjects--Peytona won.]

Evidently there was a benefit of 'bone' noticed, and while some, like Sampson, had great race careers more did not and were noted as sluggish, many had cart horse rumps and ugly heads and of course many were unsound. By our day there is probably not a Thoroughbred alive that does not have double or even triple digits of English Cart Horse in it. So that big ugly plain head that shows up in breed now and then, or that massive draft style hind-end, now you know how it got there.

With the addition of the draft into this light horse breed unsoundness had to increase. Dr. Ben K. Green made a study of the result of crossing draft with light horses and he concluded that most of the unsoundness he saw in his practice came from this cross. He explained that the genetics for large draft bone and draft conformation do not necessarily make a smooth blend with light horse genetics, rather he said often one bone in the offspring might be ruled by the smaller horse while the bone it attached to in a joint could be a draft bone, resulting in unsound joints and breakdowns in sport, and the problems can persist for generations.

"I have found thousands of horses whose bone structure and joint formation was without conformity of pattern and with no uniformity of graduation as to the stress and strain to be endured. (Green  Horse Conformation)

I want to digress a little here, to let you know I keep learning from this history. Having spent years researching bloodlines and equine history, some things are just now coming together with this information, most of which I knew before but it just didn't click fully until now. Perhaps because my perspective is from the other side of the pond (America) that I can see the effects of these additions to the gene pool more clearly now; and of course because I have studied the sport traits through time, especially in America. In colonial America there was no English Thoroughbred until just before the revolution (1730) which was 100 years after our own racehorse breed was established, and then it was really just a dribble. In the 1750s notable important typesetters Fearnought and Janus arrived, but only 165 true Thoroughbreds arrived in America before our revolution (see Legacy of Lexington and Standardbred Sport Horses).

Seeing the breeders in Massachusetts colony alone were shipping 3000 horses a year out of the Rhode Island ports to the Indies in the mid-1600s (Rhode Island was part of the Massachusetts colony), the Thoroughbred intrusion into our gene pool was really negligible until well after our revolution. Our native racehorse, the Running Horse, arose from Hobby and Running Horse imports from 1611 to 1666, and except for a few maybe at the very end of this period there was not even any Turkoman or Barb in them. In 1669 the colonies were so glutted with horses that legislation was put in place to block all importations. Most of the imported horses, especially the Irish Hobby brought to the Virginia colony, was sport stock (Virginia had a treaty with Ireland for the supply of all its sheep, cattle and horses), and the Hobby was relatively undiluted with other breeds there and selectively bred for racing and hunting, while the Massachusetts colony had more of a mix, and they banned horse racing.

So, both before and while the British Isles was eradicating their speed source (English Civil War), we in the colonies were receiving the old racing stud stock. The report of those horses, both domestic observations and those from visiting foreigners, highlight the traits of that pre-Thoroughbred breed. It was a small, docile, sweet-tempered, sure-footed, stamina loaded horse that also possessed blistering speed. (You can read more about this stock in Standardbred Sport Horses and American Running Horse).

After the revolution, especially around 1800 there was a notable outcry about the lesser quality of the newer type Thoroughbred coming into the country, which had changed from a heat-racing horse to a classic distance performer, plus had by then the full effects of the Oriental and draft additions in evidence. While the earlier imports were greatly admired by the breeders for their size and elegance they brought to the American Running Horse, without reducing speed; but by 1800 the situation had changed and complaints became continual of a rise of unsound stock, bad disposition, bad hooves, no stamina, no speed in the imports and of course then in the crosses. So what happened?

[American Running Horse, engraving by Alexander Anderson, showing the original type, drawn around the time of the first foundation movement.]

It was the Barb description of intemperate disposition that connected the dots for me this time. The post-revolutionary American breeders had coined the term 'English disposition' for the high strung, flighty fault found in the more recent English stock. And of course crossing in draft may give bone, but it also caused unsoundness and the terrible vice of 'stumbling' that Henry Herbert (aka Frank Forester) and others noted at this time, that the English breed was infected with the vice of stumbling, along with the previously noted bad hooves and lack of stamina and speed. 

The great American breeder, John Randolph (1773-1833) in 1832 spoke out strongly about the inferior stock being brought into the country: "...worthless stallions, and introduced the flat, thin-soled, weak crusted foot that can hardly hold a shoe, and cannot travel five miles without one...seriously injure our stock." He also compared the imported Thoroughbred's (aka fashionable horses, long backed horse) racing ability with that of the Virginia Running Horses' (aka quarter horses) ability. "The truly serviceable horse is the quarter horse, being active, sure-footed, speedy, and capable of breaking down the fashionable stock [imported Thoroughbred] in a hard race of fifty, or even five and twenty miles. It is only in a race of more than a mile [classic race] or in harness, that the long backed horse can be a competitor against the quarter horse. He is a stumbler and breaks down under his own unwieldy weight." (It is interesting that the quarter horse, usually assumed to be only a sprint specialist was also a renowned stamina horse, racing well up to 50 miles! Also the introduction of 'long back' could well have come from the Turkoman who was a long-backed horse).

The effect of crossing in the newer version of English Thoroughbred was so bad that a powerful foundation movement occurred in the States, to get back to the pre-revolution type stock. This fortunate return to the root stock is what saved the original Running Horse talents and also resulted in several new sport breeds arising, such as the American Saddle Horse (precursor to the Saddlebred, Tennessee Walker and Missouri Fox Trotter), and the saving the sprint racers which provided the unmatched speed to the later Quarter Horse and American Thoroughbred, and preservation of our gaited racers (precursor to the American Trotter and later Standardbred), 

An example of the changed phenotype can be clearly seen in imported trot typesetter Messenger. He became an strong foundation of our Trotter because he was able to reliably transmit a clear, clean trotting action on our gaited Running Horse stock, along with substance. He was also noted for a vicious temperament and bad hooves, and unfortunately passed those on as well. He descends from Sampson. The early Thoroughbred horses that were received in the mid-1700s were stamina loaded as well as fast, and they were sound, but the later imports (with notable exceptions like the mighty Diomed),were a lesser horse in soundness and durability.

This information, along with the lesser amount of durable racers seen in the Thoroughbred compared to what I have seen in the Standardbred, leads me to surmise that somehow the Standardbred retained more of that original soundness and stamina that the Hobby-Running Horse possessed. And we will see below that science has something to contribute to this idea as well.

Four Earliest Achievers and their Main Dominance

In these studies, the genetic dominance is identified by pedigree (Tesio Methods) and the pedigree is read as a genetic road map (see Understanding Pedigrees). Because of the vast amount of pedigree analysis required, the 21 entries themselves, then their main dominance's pedigrees, and then the further typesetters in those horses, is so great, I do not spend the time and detail I would normally. I have developed what I call 'speed analysis' whereby I quickly determine the chief potency and ignore the lesser pedigree points. Some of you may want to revisit the horse's lineages and discover those fine points that I have missed or omitted...this is meant as an overview only, to quickly focus on the sources of these traits--if possible.

In our earliest four entries in our study: Catherina 1830 is most dominant in Snap 1750, Jorrocks 1833 is most potent in Trumpator 1782, Boston RH 1833 is most potent in Diomed, and Fashion RH 1837 is most potent in Sir Archy. (Click on each individual link below to bring up the pedigree).

Snap 1750

If you take a look at Snap's pedigree you will quickly see that the majority of early lines were Barb (or Turk)-Running Horse/Hobby. This is the true base of the Thoroughbred. Snap is a grandson of Flying Childers, who, with his full brother Bartletts Childers (aka Bleeding Childers), is a back bone of the developing Thoroughbred. Snap's strongest potency however is Leedes Arabian 5x6x4x5, a domestically bred Running Horse/Oriental cross. Also secondary strengths from Byerley Turk 4x5x5 and Spanker (who is found in Leedes Arabian) is 5x5x7x6x7 and Hautboy is 6x4x5 (1/2 to 3/4 Hobby).

Trumpator 1782

Trumpator carries Snap in his 3rd generation but his main dominance is Partner 4x5x4, with secondary buildups of Godolphin Arabian 4x4 and Greyhound Mare 5x4. Partner is by Jigg, a tremendously inbred horse being 2x1 to Spanker Mare; so he was bred back to his own dam, and Partner's ancestors born in 1690 or before had very few imported Orientals to descend from, and so were most likely related to those in Spanker, which makes for a very concentrated gene pool. Partner will appear in strength in several more entries. 

[Diomed 1777, imported in 1798 (at age 21) was a fortunate exception to the other Thoroughbreds being brought in to America in this era. He was not only remarkably sound, he transmitted wonderful traits of stamina, speed and soundness.]

Diomed 1777 was a very good racehorse born as the classic race was made the performance test of the English breed, a winner at 4-mile heat racings, he also won the first Derby. He was exported to America at age 21 and he bred until his death at age 31; an indication of vitality and durability in itself. He is one of the most influential English imports to America's racehorse. His greatest potency is the full brothers Flying Childers/Bartletts Childers who are 5x6x7x7x5x5x4, a very consistent genotype which was made stronger by the 3/4 siblings Blaze and Sister to Steady 4x3 pulling it forward. The full siblings Points/Bald Galloway are 6x6 as well.  and his brother are the bedrock of the early Thoroughbred horse. Flying Childers was fast and he is by the Darley Arabian, not an Arabian, now believed to be a Turk, with no parentage of course, and his dam is Betty Leedes who is inbred 2x2 to Spanker sex-balanced out of Cream Cheeks, daughter of Spanker out of Hautboy Mare, who is largely of Hobby blood and will play a strong part in other entries in our list. Points and Bald Galloway have strong Hobby blood as well. 

I believe Bartletts Childers, also known as Bleeding Childers because he was a bleeder and therefore did not race, may be the first recorded 'bleeder' in the English racehorse.

[Sir Archy 1802, a full Thoroughbred bred in America before there was an American Thoroughbred breed. Fantastic heat racer and sire.]

Sir Archy 1802 was a champion 4-mile heat racer and he is 3x3 in Fashion RH, and it is a testament to his first rate genetics that he is also 3x2 in another great heat racing mare: Trifle RH, plus the mega-sire and heat racing champion Lexington RH is 3x4 to Sir Archy. He passed on tremendous amounts of both speed and stamina and soundness; plus we know from the Standardbred Study (part I) that he was the sire of arguably the greatest racehorse of all time: Walk in the Water RH 1813.

Sir Archy is 3x4 Herod, and 5x5x6 Partner with background power of Flying Childers/Bartletts Childers 6x7x6x6x7x7x7, which makes Herod stronger... very similiar potency to that of Diomed above. We talked about Partner above; now let's look at Herod a little closer because he is fast becoming a significant bloodline.

Herod 1758 as we will see further on is a bloodline of significance in the breed as a whole, and a main ancestral source of the jump trait (Standardbred Sport Horses) in the Thoroughbred and the rest of the world's jumpers. He was a 4-mile heat racer and he became a great sire. It is hard to be fully decisive with partial pedigrees, as we will see in many of the early horses; with what is apparent in his lineage we find his strongest dominance is the Spanker Mare, an extremely inbred horse being 2x1 to Old Moroccan Mare (a Oriental-Hobby cross). She is 5x4x6x7x7x7 in Herod, plus there is a line of her sister Cream Cheeks and her brother Careless. Herod then is very much a Spanker Mare typesetter, and seeing his tremendous stature as a foundation of excellence in not just racing but in all sport, the Spanker Mare, despite her inbreeding was one wonderful mare.

Herod is often seen in the lineages through is best son: Highflyer. What does Highflyer's dam Rachel bring that makes him so strong genetically? She brings in Bartletts Childers making the full brothers 4x4, sex-balanced, plus the full siblings Points/Bald Galloway 4x4. Highflyer is a line found in critial mass in most dressage horses as well as jumpers. It is interesting that Janus 1746, an early Thoroughbred import to the States that became a foundation sire, is 4x3 Bald Galloway/Points, making it a fascinating coincidence that he was known not just for producing sprinters but saddle horses of excellence (saddle horses of the day were gaited).

Sir Peter (aka Sir Peter Teazle) is another son of Herod seen consistently. He is 4x4x3x4 Flying Childers/Bartletts Childers with a strong Fox and Regulus presence...both bring in strong Hobby genetics. Other Herod sons seen quite often are Bagot and Woodpecker.

Other consistent dominance show up in the first four and in strength in the others, such as, Eclipse, Whisker/Whalebone et al, Matchem and Regulus.

Bald Galloway 1705 is 5/8 unrecorded Oriental: St. Victors Barb and Fenwick Barb, and 3/8 unrecorded RH-Hobby.

Regulus 1739 is 4x3 Hautboy, 5/8 of his pedigree is unrecorded Oriental: Godolphin Arabian and St. Victors Barb. Strong line in St. Simon.

Matchem 1748 is 4x3 to 3/4 siblings Jigg/Sister to Leedes, and 6x5x5x4 Spanker Mare---similiar dominance in Herod.

Eclipse 1764, an undefeated racehorse (18 starts-18 wins, and if we adjust this record to actual starts it would be 45 starts and 36 wins) in the heat-racing century in England, he is 3x4x4 to full siblings: Sister to Old Country Wench/Smiths Son of Snake, and more genetic power is added to this power configuration by Snake, because there is 5x4x5x5 to the 3/4 siblings Snake/Cream Cheeks. He carries background strength of 31 lines of Yellow Turk. Eclipse is extremely potent.

The classic race standard was established in 1776 with the St. Leger (2 miles run once--dash race). In the next few decades 4-mile heat racing faded and disappeared in Britain. In America, however, heat racing continued on for another 100 years.

Whisker 1812 is the sire of the first two entries on our list, and his full brother Whalebone is the chief dominance in two others. Further, there are several other full siblings: Waxy Mare, Web, Wilful, Woful, Wire, plus their genetic full sister Pawn Junior who is out of the full sister to the other's dam: Pawn. These full siblings are found throughout the Thoroughbred in multiples, they are part of the fabric of the breed, like Flying Childers and his brother are. You will see familiar names in their lineage: their dam is by Trumpator, Snap is found 5x4, Herod is 3x4, Partner is 5x6x7x6x6x6, plus the 3/4 brothers Cade/Regulus are 5x5x5x6.

What can we gather from this data? 1. That the Oriental/Running Horse cross is truly at the base of the Thoroughbred, 2. That Flying Childers et al and Herod and his tribe, seem to be carrying forward the potency best that resulted in the strength found in these horses. Others such as Partner, Bald Galloway, Whalebone et al and Eclipse surely play a important role as well. Looking beyond the first four and their base potencies, we find the same elements stay consistently dominant for 50 years (see chart). But then at approximately Imp 1894, we see newer names appearing: Stockwell, Lexington RH, Orville, Bonnie Scotland, Galopin, Birdcatcher, Slane, Blair Athol, Newminste, Vedada, St. Simon, Touchstone, Cyllene, Dark Ronald, Fair Play, Bull Dog, Black Toney-Blue Larkspur, Teddy, Plucky Liege, Nearco-Nasrullah, Native Dancer, Phalaris and Vimy.

So let's look at the genetic components of some of the new potencies in the 19th century in order of their year of birth.

Birdcatcher 1833, who is a grandson of Whalebone and he is a Herod warehouse (5x6x6x6x7x7x5x5x5x5), along with several lines of Eclipse (5x6x5x5), found in multiples in the later born entries, and he along with his full brother Faugh-a-Ballah are a constant in sport stock of all disciplines. He is the grandsire of Stockwell, great grandsire of Blair Athol, and he is also one of the major jump lines in the world.

Slane 1833 is 3x2 to the 3/4 siblings Lady Mary/Orville, and he has Highflyer 6x5x4x4, and Herod 6x6x7x5x7x6x6x5x5x5.

Bonnie Scotland 1853 is 4x5 Whalebone et al (Herod, Snap, Partner), 5x6x7x6 Gohanna/Precipitate (3x3 Tartar, 5x5 Squirt).

Stockwell 1849 is 4x4x4 Whalebone et al, 4x4 Eleanor/Marmion (2nd dam Giantess, 3x4 Herod and 4x3 Matchem)

Lexington RH 1850 by Boston RH, he was a world champion 4-mile heat racer and even though many of his offspring were ridden off into oblivion in the Civil War, he still today holds the world sire record of 16 years lead sire. His pedigree is an example of extreme critical mass (we will see a similar concentrated design in St. Simon). He has a huge filly factor in 22 lines of Cypron, dam of Herod and Lady Bolingbroke, he also has a background power of 117 lines of Betty Leedes. He is 4x4x5 Diomed, 3x4 Sir Archy, 4x5x5 to the 3/4 siblings Orville/May/Azalia, and 5x6x6x5 to the 3/4 siblings Stamford/Walton/Royalist/Gilliflower, and 6x7x6x6 to the 7/8 brothers Sir Peter (aka Sir Peter Teazle)/ Hydes Highflyer. 

Touchstone 1852 is 3x5 Whalebone, 5x6 Prunella/Peppermint, and 4x5x5 Selim/Rubens

Blair Athol 1861 is 4x4 to 3/4 Elana/Marmion (Eclipse, Herod, Diomed), 5x5x5x6x5 Whalebone et al, 6x5 Walton/Williamsons Ditto (3x4 Herod, 3x4 Snap, 5x4x4x5 Regulus), and 6x5 Wanderer/Golumpus (3x3 Herod, Regulus/Sister to Regulus 4x4, Godolpin Arabian 6x5x5)

Spendthrift 1876 is 4x5 Emilius, 6x5x4x5 Whisker/Web etc, and Sir Archy 5x6. he is sire of Bankrupt and Kingston and is head of the stamina Fair Play dynasty. He is by the great Australian and out of Lexington RH mare: Aerolite RH, full sister to Idlewild RH, the greatest 4-mile heat racer during the Civil War. 

[In the midst of finishing up this study James Hardiman alerted me that the traditional sireline of St. Simon was not correct, that he descended not from the Darley Arabian, but from the Byerley Turk. St. Simon and his sire Galopin reshaped the English Thoroughbred, and their genetic reach is incredible, to discover they are not who we thought was distressing. Fortunately, Mr. Hardiman had already done some work on this upset and I suggest you read his report. I had to redo St. Simon's pedigree three times before I got it right, which is what you will see on the link below.]

Galopin 1872 , he is an remarkably potent horse and his son St. Simon is even more so. Galopin's main front potency is 3x4x3 to 3/4 siblings Voltaire/Nell who are sons and a daughter of Blacklock. Blacklock's sireline has been corrected as his sire Whitelock is really by Delpini, not Hambletonian. Every quadrant of this pedigree is intertwined with close sibing configurations, like a tightly wired circuit board, making him a stallion of immense ability to set type. And that front potency is focusing forward like a laser for the tremendous background critical mass in Partner.

St. Simon 1887 he is 3x5 to 3/4 Merope/Velocipede (5x3 Whiskey (Eclipse, Herod), 5x4 Sir Peter--5x4 Y.Giantess, 4x4 Voltaire, and 7x6x6x6 Orville/Orvillina (Herod). St. Simon's pedigree is much more then these mentioned dominance. Like his sire, almost every entry from the 5th generation until the 7th is involved in one or more close siblings connections. The corrected error which was Blacklock's sire Whitelock being a son of Delpini, not Hambletonian, might have been a minor adjustment if it was a single instance but Blacklock lines dominate the pedigree 5x6x5x6 and are made even stronger when pulled forward by the 3/4 siblings Merope/Velocipede 3x5. The entire lineage is all wired together making strong conhesive potency, and in the far background there is a huge concentration of 230 lines of Partner and 199 of Regulus. Also of interest in that St. Simon carries at least 30 draft crosses.

Cyllene 1895 is 6x5x6x6 Birdcatcher/Faugh-a-Ballah (Herod), 7x7x7x7x7 Whalebone et al, 4x5 Newminster, 4x4 Stockwell, and 6x6 Melbourne (4x5 Trumpator, 4x4 Sir Peter)

Dark Ronald 1905 is 5x5x6 Stockwell/Rataplan, 6x5 Landercost/Ostinia, and 7x8x7x7x7 Whalebone et al

We can see overall the above power lines have concentrated the original elements that made the breed successful. What happened when the 20th century arrived?

Fairway 1925/Pharos is 4x3 St. Simon (Partner), 4x5 Springfield, Galopin 5x4x7x6, 14 lines Rataplan/Stockwell, Newminster (Herod) power behind

Fair Play 1905 is 4x6 West Australian, 6x6x6 Emma/Maria + 3/4 Hercules, 4x7x5 Newminster, 7x5x6x7 Birdcatcher

Sweep--Black Toney--Blue Larkspur all Lexington RH concentrates via Domino lines who is 3x4x4 to Lexington RH

Bull Dog 1927/Sir Gallahad is 4x3 Concertina/Orme made stronger by Angelica/St. Simon, plus Ormonde is 3/4 brother to Doremi 5x3, 4x4 Tadcaster/The Mersey (Newminster), plus 3/4 Knowsley/Wellingtonia 5x5, lots of Stockwell/Rataplan 7x6x6x6x7

Nearco 1935 St. Simon/Angelica 5x4x4x7x5, plus a powerful Carbine-Polymelus nick by 7/8 The Mersey/Tadcaster 6x5, and 7/8 Musket/Quivewr 5x5, and 3/4 sisters Y. Melbourne Mare/West Australian Mare powering them.

Princequillo 1940 Galopin dominance (12 lines) pulled forward by St. Simon/Angelica 5x6x5 and by 3/4 siblings St. Marguerite/Dinah/Friars Balsam 6x6x6

Zeddaan 1965 4x4 Pharos/Fairway--made stronger by 3/4 siblings Maid of the Mist/Lemberg/Polymelus 6x6x6x5x5x5, also 6 lines of Cyllene, 32 lines of Galopin in the background.

The largest aggregates of durability blood then appear to be Herod (Spanker Mare) and Partner (Spanker Mare through his sire Jigg). Spanker Mare is truly the mother of the Thoroughbred, and the provider of the talent and durability. This power is carried forward by Herod and Partner concentrates consistently. For example the great line of Birdcatcher is a Herod warehouse, as is Newminster and Lexington RH, while Galopin and St. Simon are Partner genetic bombs. Some power lines such as Sir Archy and Whisker et al (and others) are channels of both Herod and Partner in concentrated doses.

Clues from Science

[Eclipse 1764, painted by George Stubbs]

Besides the Y chromosome study by Dr. Wallner, there are a couple of scientific papers that provide some interesting material for us. First is one that appears to show that only 10 ancestral horses have control of 82% of the Thoroughbred gene pool, and we will see some familiar names in those. And second is the discovery of another gene that appears to bolster stamina and durability.

1. Byron Rogers in his April 24, 2018 article: "How inbreeding effects racing performance in Thoroughbreds" gave us a synopsis of the 2017 study by E. Todd et al "Founder-specific inbreeding depression affects racing performance in Thoroughbred horses". In the study over 135,000 Thoroughbreds in Australia were evaluated by two methods: Barmong's Ancestral History Coeficient and by Wrights Inbreeding Coefficient [Wrights Inbreeding Coefficient is controversial], to determine the amount of inbreeding in relation to performance. It appears their definition of inbreeding is more what we call 'critical mass', where the lines of an ancestor become so great that it rules the phenotype (like Partner in Galopin and St. Simon). Normally we define 'inbreeding' as duplication in the 3rd generation or closer, but that is clearly not what is meant here. The horses included in the study raced between 2000 and 2011, so fairly recently and the ancestors they refer to are in the 1700s. Therefore I believe they mean aggregate accumulation of genotype or what we call critical mass.

Nevertheless, they determined that 82% of all Thoroughbred genetics are rule by just 10 ancestors! The identified typesetters are in order of their genetic impact:



St. Simon

Godolphin Arabian



Rachel (dam of Highflyer)



Roxana (dam of Cade)

And it was further determined that of those 10, that especially four ancestors had a clear negative or positive effect on performance. Critical mass in Herod and the Godolphin Arabian had a measurable positive impact on racing performance. In contrast they found that especially dominance in Touchstone, and also Stockwell and Ecilpse had a negative impact on performance. The rest fell in the neutral area. Surprising isn't it?

"The authors found that inbreeding to four ancestors had significant effects in racing performance. Individuals who were more inbred to Herod had greater cumulative earnings per start and length. Conversely, inbreeding to Eclipse, Stockwell and Touchstone (in particlular) had negative effects on the racing performance of their descendants." (Rogers)

Herod had no draft lines in him, but neither does Eclipse. Both Touchstone and Stockwell have double digit draft lines. While the draft component surely does not help speed or soundness, this study also includes Eclipse as a negative, who has no draft in him. Therefore this draft factor cannot be the only reason there is such a difference in  accumulative effect that this study writes about.

Herod also showed up as the key bloodline in the show jumpers of the world in a earlier study of mine (see Standardbred Sport Horses), and he also is a line of excellence in the Standardbred via its galloping Running Horse elements. Herod has a Byereley Turk sireline, which is what St. Simon's is now identified as.

Both Herod 1758 and Eclipse 1764 were fantastic racehorses and stallions and have left an indelible typeset on the Thoroughbred. I had to redo my version of Eclipse's pedigree because of errors in the traditional version.

In Eclipse the greatest background dominance power noted is Yellow Turk (31 lines). In all our early pedigrees there are large portions that are unrecorded, and so any dominance shown has to be understood to be a guess, because we have no idea of what the unrecorded ancestors were or what they brought to the mix. He has a closer up potency in the 3/4 siblings Snake/Cream Cheeks 5x4x5x5, made stronger because it is focused forward through the full siblings: Sister to Old Country Wench/Smiths Son of Snake 3x4x4. This makes Eclipse an extreme typesetter, and his career shows he contains fantastic performance attributes.

 We find similar potency in Herod, who has a background dominance in Fairfax Barb (Moroccan Barb--19 lines), through Old Moroccan Barb (18 lines), which is focused forward by 5x4x6x7x7x7 Spanker Mare and again keep strong by the 3/4 sibliings Jigg/Bald Peg/Betty Leedes 3x4x4. Both carry a very similar design but with a different background dominance. Was the Fairfax Barb in someway more vital than the domestic Yellow Turk? I have no way of knowing. Or was the Spanker Mare dominance much superior to Snake/Cream Cheeks? I can see that Herod's lineage has a strong female element while Eclipse's is more colt factors, and so, is it the strong filly factors in Herod what makes the difference? I cannot see a clear cut reason why Herod rates so high above Ecilpse, perhaps some of your can tell me.

Truly, I cannot see any reason why Eclipse would be a negative in these analyzed results, all the data I have on him points to him being a top genetic package.

This report shows that most of the horses we found in power behind the durability stars are also a potency in most Thoroughbreds, and the study's surprising conclusion that Herod is the most positive conduit reinforces some of what we found, but the negative status in this study of Eclipse is a puzzle, as he appears to be potent in our durable and sound racers.

2. Dr. Daniel Polaski et al in 2018 published "Detection and Analysis of Polymorphism in the Promate Region of Equine PPARGCIA gene", a gene which seems to support our findings so far.

The PPARGCIA gene is located in the 3rd chromosome and helps regulate energy metabolism, apparently with some relation to muscle types and the scientists see indications that this gene affects athletic performance. The study was conducted in Poland and 9 horse breeds were tested, and then 2 groups of Thoroughbreds. The breeds were: Arabian, Holstein Wielkoplski, Standardbred, Deutsche Reitpony, Polish Heavy Draft, Polish Konik, Hutsul and then the Thoroughbreds divided into an elite group and a non-elite group.

"Because of its proven role in the skeletal muscle response to exercise [previous studies] PPARGCIA gene should be considered as a good candidate gene responsible for athletic performance in equine breeds."

There were 3 variants of the gene: CC, CG, and GG. All breeds carry CC except the Arabian, and the Hutsul carried CC and no other. The variant GG was found only in the Standardbred, Polish Heavy Draft and Arabian. While the GC was found in strength in the elite group of Thoroughbreds (winners up to 2 miles), less so in the non-elite group; so it was a measurable difference in racing performance seen.

On GG: "While it is present in other closely related breeds to the Thoroughbred, in the Arabian and Standardbred, there was an absence of the GG genotype in the racehorse sample studied." The team, however, mentioned that their Thoroughbred test groups that were drawn from classic racers and did not include stayers beyond 2-miles or the National Hunt Horses (steeplechasers)...those groups were not tested and they believe perhaps GG would show up in those. The GG version of the gene's presence in the Polish Heavy Draft was attributed to its high strength and endurance. The GG carrying horses were seen by the scientists to be more durable, sound and strong than the others.

In this science test we receive confirmation that endurance and durability is present in higher amounts in the Standardbred then the Thoroughbred which is just what we are seeing so far in this study. And perhaps the historical record of a drastic change in the phenotype of the English racer after the classic performance test replaced the tougher heat racing test, and with the introduction of the draft lines. 

The Standardbred, more than any other of our sport breeds contains more of the original Hobby-Running Horse seed stock from its Narragansett Pacer and Virginia Running Horse inroads, along with the descendant breeds that were absorbed into the stud book: American Saddle Horse, Canadian Pacer, Morgan and Pacing Running Horse. Thoroughbred was added to the gene pool but makes up no more than 30 or possibly 40% of its genetics. The fact remains that the original Hobby--Running Horse is in greater amounts in the Standardbred.

Next study, Part III, will center on the Quarter Horse and hopefully provide more information on sound bloodlines.


Bower, Dr. Mim et al " The cosmopolitan  maternal heritage of the Thoroughbred racehorse breed shows a significant contribution from British and Irish native mares." 2010  "Investigation into Eclipse", "Investigation into St. Simon" "English Half-Crown Horse"

Green, Dr. Ben K.  Horse Conformation as to Soundness and Performance 1969

Hill, Dr. Emmeline et al "The genetic origin and history of speed in the Thoroughbred racehorse." 2012

Holmes, Laura  "Racehorse Reality Check: Do Numbers Matter? 2018

Kirsan, Kathleen Legacy of Lexington 2015, Standardbred Sport Horses 2018, "Understanding Pedigrees", "Tesio Methods", "Origin of Sport Ability", "Irish Hobby"

MacKay-Smith, Alexander Speed and the Thoroughbred--the complete history 2000

Polaski, Dr. Daniel et al "Detection and Analysis of Polymorphism in the Promate Region of Equine PPARGCIA gene" 2018

Wallner, Dr. Barbara "Y Chromosome Uncovers the Recent Oriental Origin of Modern Stallions" June 2017 (Current Biology)

This is part II of a three part study. The introduction is here, part I: the Standardbred and Soundness is here.  Part III- the Durable Quarter Horse plus the entire study conclusions here.

American Running Horse - series documenting the colonial development