Just what is it that makes up a champion racehorse?
Speed, certainly. Stamina, without a doubt. But, besides conformation, what
factors are related to speed and stamina? Good racehorses come in all
shapes, and the best built yearling at the sale doesn't always turn out a
winner. Mentally, the potential champion needs a number of factors, not the
least of which is courage. Willingness to run is at least as important as
ability. Physically, one thing a successful horse needs is adequate lung
capacity. Another is an efficient heart muscle.
Heart size radically affects the performance ability of
the thoroughbred athlete, and it has recently been discovered that the gene
which causes an exceptionally large heart is located on the x-chromosome.
(The Australians were decades ahead of the rest of us, but it seems no one
was listening.) Therefore, a colt can only inherit an oversized heart
through his dam, and a stallion can only pass on the gene to his daughters.
The exact heart size seems to vary from horse to horse. Multiple factors
probably contribute to heart size, and the x-factor gene, being a mutation
itself, probably works in conjunction with these; it "supersizes" the heart
based on the existing blueprint, so to speak.
The first known case of an oversize heart was Eclipse,
foaled in 1764, and he passed that gene on to many of his daughters. It is
my opinion that the phenomenon known as an exceptional broodmare sire is a
stallion who carries that gene. His sons can't inherit it, but his daughters
can. And so can their offspring. Therefore, his daughters' sons are given
the potential to significantly outperform his own sons.
The most famous such example is Secretariat. His autopsy
showed beyond a shadow of a doubt that he had an oversized heart, weighing
in at 22 pounds, nearly three times that of the average thoroughbred, and
more than three times that of an average non-thoroughbred horse.
Secretariat's stud career wasn't unsuccessful, but while
he passed on to his sons many outstanding characteristics, none of them
displayed their sire's ability to sprint for a mile and a half, annihilating
top notch fields and world records in the process. Essentially, Secretariat
had inherited brilliant speed from his sire, the great Bold Ruler, but it
was from Somethingroyal that he inherited the stamina to maintain it for
classic distances. A horse tires when oxygen debt makes his muscles ache. A
larger, more efficient heart enables those muscles to receive optimum oxygen
for a longer period of time, provided that lung capacity is more than
adequate. This therefore increases stamina. Secretariat's extreme example of
a large heart probably greatly accounts for his seemingly unnatural ability
to turn in performances like the 1973 Belmont Stakes.
Secretariat's second physical advantage can be
demonstrated by viewing his Marlboro Cup. His stride so dwarfs that of Riva
Ridge, a dual classic winner himself, that Secretariat takes one stride for
every two taken by his stablemate. With these two weapons in his arsenal,
Secretariat was able to become more than a champion. He was a legend.
Man o' War had the same two weapons. He was also a
legend. These two were also big, powerfully built horses with excellent
conformation. Conformation faults, and most horses possess many, can cause
numerous problems. If a horse had an oversized heart, but failed to stay
sound due to conformation defects, he might become a champion, but certainly
not an infallible one. If a horse had an oversized heart, but a straight
shoulder, he would fail to have a long enough stride to take full advantage
of his heart capacity. And, if a horse has good conformation and the other
factors necessary for speed, he could certainly become a champion without an
oversized heart, and many no doubt have. He would just work harder for his
wins than those who had it. He might perhaps limit his greatest triumphs to
shorter distances, or, since every horse to win at a mile and a half doesn't
have the luxury of an oversized heart, he would have to be rated like a
mortal animal, where with the likes of Secretariat and Man o' War it was not
necessary. Certainly increased stamina can be trained into a horse. Bold
Forbes, a sprinter by nature, won the mile and a half Belmont Stakes due to
masterful training and careful rating. Ack Ack was also better at shorter
distances, but he got a mile and a quarter several times. The x-factor is
not common enough to attribute all feats of speed and stamina to it, or to
state that to be a success, a horse must possess it.
Increased heart size makes everything easier, naturally,
but for it to serve as an advantage it must be a gift possessed by less than
It is true that a majority of thoroughbreds possess a
heart that, on average, is two pounds heavier than that of other breeds. But
it is when the heart size exceeds that significantly that the horse gains
advantage over his rivals, and that difference is linked to the x
Let's look at the stud career of Secretariat more
closely. His greatest star was a daughter, Lady's Secret. Horse of the Year
in 1986, and an impressive performer despite her lack of size, she is a
definite suspect in the search for the X Factor. She wasn't unbeatable, for
she didn't possess the size, powerful build, and great stride of her mighty
sire. But she was sound and well made. D. Wayne Lukas called her an
overachiever, and he very well may have summed it up in that one word. An X
Factor horse will, given the chance, outperform its size and/or
conformation. Her wire to wire sprint to win the mile and a quarter Breeders
Cup Distaff is exactly the kind of performance that the oversized heart
makes possible. While she has yet to pass on her ability to her offspring,
time may very well tell. We'll look at her broodmare sire, Icecapade, a bit
Also notable was Secretariat's son General Assembly. A
beautiful colt, he inherited his father's good looks, conformation, and even
some of his speed. He could not, however, inherit Somethingroyal's x
chromosome, and therefore he could not match the performance of his sire. He
was probably the second best two year old of 1978, and at three he won the
Travers Stakes and the Vosburgh Handicap. He was by no means a dud. Having
failed to successfully tackle Spectacular Bid in the Kentucky Derby,
however, he was criticized for failing to meet expectations arising from his
sire's uncanny abilities. In 1979, no one (outside of Australia, anyhow) was
aware of the sex linked nature of heart size, although the phenomenon of the
broodmare sire had been well known for two centuries.
As a broodmare sire, Secretariat had much greater
success, and was responsible for the remarkable mare Weekend Surprise, dam
of Horse of the Year and Belmont Stakes winner A.P. Indy as well as
Preakness winner Summer Squall. Secretariat's daughters also produced Storm
Cat, Chief's Crown, Dehere, and more.
Now we come to the exception that proves the rule. Risen
Star was by far Secretariat's best son, winning the Preakness and Belmont in
1988. His success reminds us of two facts. First of all, he may have had the
x-factor; just because he couldn't inherit it from his known carrier sire
doesn't mean he didn't have it, since his dam could have been a carrier.
Secondly, we are reminded that heart size is not the only characteristic
that makes a successful racehorse. Man o' War's entire stud career shows
that clearly enough. He sired sixty four stakes winners, including the
outstanding colts War Admiral, Crusader, American Flag, and War Relic, as
well as the Kentucky Derby winning gelding Clyde Van Dusen. Man o' War
passed on many of the qualities that made him a champion. But, he too failed
to reproduce himself, because even Man o' War couldn't alter the rules of
science and pass an x chromosome linked trait on to his sons.
Of course, his daughters were more consistently
outstanding, and as a broodmare sire he produced 128 stakes winners and
eight champions. That his son War Admiral was also a great broodmare sire
was a coincidence possibly created by the fact that his dam Brushup was
probably a carrier of the x factor. This would explain the Admiral's
impressive performance, which despite his smaller stature outshone the deeds
of Man o' War's other sons. It was Crusader who most resembled Man o' War
physically; had conformation alone been responsible for performance, than
Crusader surely would have reigned over War Admiral.
Brushup was a daughter of successful broodmare sire
Sweep, whose daughters included Dustwhirl, the dam of Whirlaway. Two time
champion and Belmont Stakes winner Sweep was out of the good mare Pink
Domino, whose amazing sire Domino is a suspect. Both Domino and Whirlaway
possessed a dangerous turn of speed that made people question their reality.
Once again, it takes more than the x-factor to create talent on that level,
but it would certainly help. Both Domino and Whirlaway died young,
unfortunately, limiting the number of offspring they produced, but Domino
did very well siring top colts as well as good mares, and obviously
possessed a complete package of outstanding characteristics. War Admiral, if
he was an x-factor horse, may have inherited the gene in another manner, but
Domino is a pretty strong suspect.
War Admiral's daughter Busher was almost certainly in
possession of an exceptional heart. Horse of the Year in 1945, she
successfully handed defeat to older males as a three year old. Those she
conquered included Armed and Stymie. She carried weight and won at a
distance, setting a track record at a mile and a quarter. As a broodmare,
she produced the stakes winner Jet Action, and might have had more success
had she lived past the age of thirteen. She had but five foals. Her full
sister Striking was an outstanding broodmare and a Hall of Fame member. To
display the trait, they would need to be homozygous, of course, but Busher
and Striking each had a double chance to inherit the x factor. Their dam,
Baby League, an above average broodmare, was out of the great La Troienne.
Dam of Bimelech and Black Helen, La Troienne was almost certainly a carrier.
We could spend all day speculating about what horses had
or didn't have the magical x-factor gene. The only ones that can be proven
beyond a shadow of a doubt are Secretariat, Phar Lap, and Eclipse, all of
whom had their hearts weighed after death. Let's try to follow the path of
the x chromosome in Secretariat back to Eclipse.
Somethingroyal, being a mare and therefore receiving two
x chromosomes, could have inherited it from either parent, or both. Both
were outstanding individuals, and both very well could have been carriers.
Princequillo was known for his endurance, with wins including the Jockey
Club Gold Cup, he led the Broodmare Sires list seven times, and was the
broodmare sire of numerous high class horses and classic winners on an
Princequillo also sired several colts with notable
staying ability, however, including two sons who exceeded his
accomplishments, Round Table and Hill Prince, so either he was fortunate to
meet up with two x-factor mares, or there was more to his talent than
x-factor alone. Or, as is most likely, both of these statements are true.
Princequillo's dam was Cosquilla, a daughter of the
English champion Papyrus, whose second dam was a St. Simon mare. St. Simon
is definitely a suspected carrier. He had more than his share of positive
qualities, and therefore by passing those on he produced several outstanding
sons, Persimmon and Diamond Jubilee among them (note both were out of
Hampton mares...), but his daughters had great success on the track as well
as in their careers as broodmares, producing such greats as Rock Sand, an
English Triple Crown winner and outstanding broodmare sire. It was from Rock
Sand that Man o' War most likely received his magic chromosome.
Somethingroyal also could have inherited the x chromosome
she passed to Secretariat from her dam, Imperatrice. A solid performer on
the track, this fine mare produced several stakes winners. A quick glance at
a five generation pedigree for Imperatrice leads me to accuse Isinglass
first. An English Triple Crown winner, beaten but once, he sired the second
dam of Caruso, the sire of Imperatrice.
Isinglass was by Isonomy, a possible carrier, but the
gene can't be passed from father to son. Looking at Deadlock, his dam, we
quickly see that her sire Wenlock was out of Mineral, a Rataplan mare.
Rataplan is a good son of the great broodmare Pocahontas, and she is one of
the strongest x-factor suspects in the stud book.
One thing may appear puzzling. Somethingroyal could have
been homozygous for the trait, but if that were the case, why couldn't her
daughter, The Bride, manage to win something more than a coin toss?
The answer is that this trait is recessive in the female,
but dominant in the male, as are many sex linked characteristics. The female
has two x chromosomes, while the male only has one. He will therefore
express the gene, while the mare won't unless homozygous. (A good example of
a recessive sex linked trait would be hemophilia). So, if Somethingroyal is
homozygous for the x-factor, which is possible, shouldn't The Bride have
passed on the x-factor to approximately half her offspring? In theory, yes,
but luck is luck. Ask any breeder of pintos what percentage of pinto foals
they manage to produce from a heterozygous pinto stallion when bred to a
solid mare, or vice versa. In theory, this cross has a 50/50 chance every
time. In practice, since each such cross has 50/50 odds, and the last result
does not affect the next, it may take four or five such crosses to produce
one pinto foal.
For a quick example of how well 50/50 chances tend to
actually result in the desired outcome half of the time, flip a coin ten
times. You should get heads five times. You won't. Now add to that the fact
that the trait caused by the x-factor gene will only stand out in male
offspring, and then only if they get the opportunity to show it. (The Bride
did produce two stakes winners, At Ease and Heavenly Match.) And finally,
consider the fact that The Bride was won in a coin toss where the loser got
Now, we have decided that in all likelihood Princequillo
was an x-factor horse, and that the gene he inherited had a good shot of
being passed through St. Simon. We also suspect Imperatrice of being an
x-factor horse, and we've chased that gene, through a few educated guesses,
So, having accused the great St. Simon of passing the
x-factor gene to both Man o' War and Secretariat, we should look at him more
closely. An undefeated champion who destroyed his fields, winning the Ascot
Gold Cup by twenty lengths; A great sire and a great broodmare sire. If you
look at a picture of the great horse, you can't help but notice the deep
slope to his shoulder, and the muscling that was evident even late in his
life. He undoubtedly possessed a tremendous stride, and that was a trait he
could pass on to his sons as well as his daughters.
St. Simon received his Y chromosome from his sire, the
speedy but not quite immortal Galopin, winner of the Epsom Derby. His x
chromosome came from his dam, St. Angela. She was by King Tom, and his dam
was Pocahontas, who we already said is one of the strongest x-factor
suspects in the stud book. She was the dam of Rataplan and Stockwell.
Rataplan won the Doncaster Cup and 21 Queen's Plates. He was also broodmare
sire to several English classic winners.
Stockwell, beaten but once in his career, was a dual
classic winner and was such a great sire they called him "The Emperor of
Stallions". Once again, his outstanding performance depended on more
qualities than a large heart, a fact proven by both performance and the
success of his sons, but it certainly didn't hurt. His daughters produced a
number of outstanding horses, including Isonomy.
Now, if she indeed had it, from which parent did
Pocahontas receive her x-factor? Both, quite possibly. This mare very well
was homozygous for the x-factor. She was racing while in foal, in stakes
company and not without success. No mere mortal mare could perform that way.
Glencoe and Marpessa are each suspects, and they no doubt both contributed
to her other positive qualities as well.
Glencoe won the 2,000 Guineas and the Ascot Gold Cup, and
was a top broodmare sire in America. Several outstanding sons of Lexington
were out of Glencoe mares, including Kentucky, Asteroid, and Norfolk.
Marpessa's tail female line reads as follows:
Marpessa by Muley (out of Eleanor by Whiskey)
Clare by Marmion
Harpalice by Gohanna
Amazon by Egremont's Driver
Fractious by Mercury
Mare by Woodpecker
Everlasting by Eclipse
Hyaena by Snap
Miss Belsea by Regulus
Mare by Bartlett's Childers
Sister 1 to True Blue by Honeywood's Arabian
Dam of the Two True Blues by Byerly Turk (Taproot #3)
It is reasonable to suspect that the x-factor quietly hid
for generations, then expressed itself in Pocahontas when homozygous. The
other possibility is that it came through Muley, as Whiskey had the chance
to inherit it from his third dam, who was by Regulus. (More about Regulus
shortly) Neither Whiskey nor Muley displayed the x-factor very strongly if
this was true, but it is possible.
Trampoline, the dam of Glencoe, is also a suspect, as is
her dam, the remarkable Web. Prominent members of family #1, these mares'
careers lead one to believe that they were almost certainly carriers.
Yet here we may be reminded that there is more to an
outstanding racehorse then heart size.
Look at Web's pedigree. All of the outstanding bloodlines
of her time are represented. You can literally see the ingredients of the
modern thoroughbred displayed here, from their sources, so to speak. From
the Godolphin Arabian and his sons Regulus, Cade, and Blank, we get powerful
muscling and depth of shoulder. Cade's son Matchem was noted for his great
endurance, while the Darley Arabian's sons, including the great Flying
Childers and his brilliant grandson Snap, contributed speed. But it is from
Eclipse that we supposedly get the mutant, sex linked gene we call the
x-factor. And when we look at Web's pedigree, we see several crosses to
Eclipse, yet no crosses that could have passed his x chromosome to her.
This leaves us with two possibilities; was she indeed a
carrier, or were other traits responsible for her success? and if she was a
carrier, then what ancestry does she share with known carrier Eclipse?
Let's explore the possibility of Regulus as an X factor
horse. Eclipse, his grandson, was the first known carrier. This does not
mean, necessarily, that Eclipse was the originator. The original mutation
may be found in the pedigree of his dam, the successful racemare Spiletta.
Looking at a five generation pedigree, instincts lead me to two suspects.
Regulus, Spiletta's sire, and Cream Cheeks, second dam of Easby Snake,
Spiletta's broodmare sire. Regulus was vastly superior to his rivals and a
superior broodmare sire who failed to reproduce himself in his sons. He
actually fits the description of an x factor stallion better than does his
known x factor grandson, who was an outstanding sire, although he did not
Cream Cheeks, being the second dam of Flying Childers,
who was also vastly superior to his rivals, would be the second suspect.
When her daughter Betty Leedes was crossed with the Darley Arabian, his
speed producing characteristics and the mysterious x-factor gene may have
met for the first time. The result? Whether the x-factor was involved or not
the cross produced England's first great racehorse, the undefeated and
legendary "Mile a Minute Childers." If the x-factor was involved, this would
make Easby Snake a carrier; I see no evidence of this. Granted, he may have
lacked the opportunity to display this trait, so we may never know. The
Darley Arabian's male line produced plenty of speed, and Flying Childers
would not have needed the x-factor to overwhelm his competition early in the
eighteenth century, just speed and quality.
If Eclipse was not the original x-factor horse, but
instead inherited the gene, then odds are good that Regulus was also an
x-factor horse. Let's look at the stud career of Regulus. He was the
broodmare sire of both Eclipse and of Rachel, the dam of Highflyer. If one
were to compile a list of the ten best horses of the eighteen century, these
two would undoubtedly top the list. Highflyer was undefeated in twelve
starts, and he was extremely successful at stud. He sired both sons and
daughters of exceptional quality, especially when put to Eclipse mares. A
big horse, he possessed speed, stamina, and exceptional conformation.
X-factor or not, his offspring received many gifts from him.
Sir Peter Teazle, perhaps the best of Highflyer's sons,
was out of Papillon by Snap. His second dam, Miss Cleveland, was by Regulus,
so Sir Peter may also have had a chance to be a carrier.
Now, if Trampoline's x-factor came not from Web, then
from where? Her sire, Tramp, was good, but not superior. A Doncaster Cup
winner, he sired some good horses, but he doesn't leap off the page and
shout x-factor. Looking at his pedigree, we see that while full of Eclipse
blood, none of the crosses fall where they need to in order to pass on an x
chromosome. The case supporting an accusation of Web, and therefore probably
Web, a daughter of Epsom Derby winner Waxy, is from a
long line of successful broodmares. Penelope, winner of eighteen races, was
a remarkable broodmare and a strong suspect, as is Prunella, her dam, who
produced the classic winners Waxy Pope and Pelisse. Prunella was by
Highflyer. We have already used Highflyer's greatness to support the case
for Regulus, so we know that if Regulus was a carrier, so was Highflyer.
Waxy is a tail male descendant of Eclipse, but the x
chromosome can't move that way. He is out of Maria, a daughter of Herod. His
second dam is Lisette by Snap. This is an outstanding pedigree, full of good
genetic material, but it seems to lack a magic x chromosome. Web's x-factor
had to come through Penelope.
Herod was no doubt one of the top horses of his century,
but his success as a stallion is too good for him to be an x-factor suspect.
He sired the winners of 1042 races. Not 142. One thousand forty two. While
it was Eclipse's male line that eventually dominated, it was Herod who was
the better sire at the time. And this despite the fact that Eclipse was the
superior horse. I could be wrong, but I believe that Herod's success had to
come from factors that could be inherited father to son, combined with the
advantage of being bred to daughters of Regulus and later Eclipse.
Furthermore, there are no x factor suspects in the correct places in Herod's
pedigree; it contains no crosses to Eclipse (which would have been
impossible since Eclipse was younger than Herod); he shares no correctly
positioned common ancestors with Eclipse; and his most noteworthy ancestors
are not in the position to pass down an x chromosome:
Jigg by Byerley Turk Partner Sister to Mixbury Galloway-Curwen
Bay Barb Tartar Fox by Clumsey Miliora Milkmaid by Snail Herod (1758) Flying
Childers by Darley Arabian Blaze Confederate Filly by Grey Grantham Cypron
Bethell's Arabian Selima Graham's Mare by Graham's Champion
Matchem, the third linefounder from the eighteenth
century, was also probably not a carrier. His dam, called Changeling's Dam
or A Sister to Miss Partner, was a daughter of the champion sire Partner and
Brown Farewell, a good mare by Makeless out of a Brimmer Mare. Brown
Farewell was a female line descendant of the Layton Barb Mare. This makes
Matchem a well bred horse of his day, especially seeing as he's by Cade, and
Matchem certainly demonstrated his quality both on the racehorse and at
stud, but there seems to have been no chance for him to inherit the x-factor
Now, if we leave the eighteenth century and look at those
horses who have truly demonstrated greatness in the twentieth century, who
might be a carrier? We know that Secretariat, Man o' War, and Phar Lap were.
We think that War Admiral, Busher, and Whirlaway may have been. How about
Citation, Kelso, and Ruffian?
Citation was an extraordinary horse. He was by leading
sire Bull Lea, but his success went beyond the speed Bull Lea was known to
sire. Not only was he a Triple Crown winner who beat older horses, including
a former Horse of the Year, in February of his three year old year, but
after missing his four year old season, he made the most successful comeback
in the history of racing, turning in multiple world record performances, and
becoming history's first equine millionaire.
Hydroplane II, Citation's dam, was by Hyperion, who was a
European champion and classic winner despite standing a mere fifteen hands
high. Definitely a suspect. Hyperion's dam was the outstanding producer
Selene. Tried and convicted.
Selene produced Sickle and Pharamond II, whom among other
things were both very successful broodmare sires. She was by St. Simon's son
Chaucer, and while the x-factor couldn't have traveled that path, his speed
and power were passed to her sons. Her x-factor possibly came through her
broodmare sire, Tristan, who was out of a Stockwell mare. Tristan won the
Ascot Gold Cup, as well as three runnings each of the Hardwicke Stakes and
the Champion Stakes. He was also the broodmare sire of St. Leger winner
Swynford, who also won the Eclipse Stakes and two runnings of the Hardwicke
Kelso won five Jockey Club Gold Cups. He was Horse of the
Year five times. He repeatedly gave significant weight to younger horses of
notable ability. And his second dam was out of a Man o' War mare. Kelso's
x-factor could also have come from his broodmare sire Count Fleet, whose
breathtaking performance in sweeping the 1943 Triple Crown deserves an
accusation as well. And Count Fleet's third dam was a Rock Sand mare. So yes
to Kelso, and probably yes to Count Fleet as well. And both have Rock Sand
to thank, as does Man o' War himself.
Ruffian certainly performed like an x-factor horse. She
destroyed her fields and a number of stopwatches, and displayed the ability
to sprint over a distance, always leading wire to wire. To display the
trait, she would need to be homozygous. Her dam Shenanigans was by the great
Native Dancer, an x-factor suspect with a big stride who in turn was out of
a Discovery mare. In addition to Ruffian, Shenanigans also produced
Icecapade, a good stakes winner and the broodmare sire of suspected x-factor
mare Lady's Secret. Shenanigans was out of Bold Irish, and therefore comes
from an impressive female line and is a suspect as well.
Reviewer sired Ruffian, and while he wasn't a great
horse, he was a solid stakes winner, and he had a double shot at inheriting
the x-factor. His broodmare sire, Preakness winner Hasty Road, was by
Discovery. His third dam was by Blue Larkspur. Both Discovery and Blue
Larkspur were great horses themselves, and both were the very definition of
great broodmare sires. Reviewer was also the broodmare sire of the champion
mare Laugh and Be Merry.
Asked how to breed a champion, Alfred Vanderbilt
responded "just breed any sire to a Discovery mare." This accurate statement
resulted in, among others, Native Dancer, beaten but once, two time champion
Bed o' Roses, and Bold Ruler, classic winner, champion, and Horse of the
Year despite numerous injuries.
The mighty handicap champion and Horse of the Year
Discovery won three Brooklyn Handicaps and carried as much as 139 to
victory. Assigned 143 pounds on one occasion, it took the good horse Esposa,
with a weight assignment of 100 pounds, to beat him.
Discovery was by Display, a tough horse himself, but if
he possessed the x-factor gene it came through his dam Ariadne, whose second
dam was by Hamburg, and whose sire was out of a Isinglass mare. Hamburg was
a Horse of the Year, and his second dam was Mannie Gray, the dam of Domino.
Hamburg's best offspring was the brilliant filly Artful. As a broodmare
sire, Hamburg was responsible for, among others, the Kentucky Derby winning
Three time Horse of the Year Forego, another giant of the
handicap ranks, was out of Lady Golconda by Hasty Road, who was out of a
Discovery mare. And his third dam was Whirling Girl by Whirlaway.
To firm up our accusations of Whirlaway, War Admiral, and
Sweep, let's look more closely at Domino's pedigree. His speed comes down
from his sire, Himyar, by America's first great sprinter, Alarm. The
x-factor would be passed from either Lexington, who appears repeatedly on
his dam's side, or Lecompte, sire of his third dam and the son of a Glencoe
Lexington, as an x-factor horse, is a strong possibility,
although he is another one of those horses who had it all. An amazing
performer and an outstanding sire, his male line all but died out despite
the success of his sons on the racetrack, and his position as America's
leading sire for a record sixteen consecutive years. As a broodmare sire,
Lexington got such horses as Hindoo, Luke Blackburn, Salvator, Spendthrift,
Survivor, Saunterer, Springbok, Ten Broeck, Vanguard, Montague, George Kinny,
Aristides, Ben Ali, Day Star, and Grenada. This list reads like a who's who
of the 1870's and 1880's.
Alice Carneal, the dam of Lexington, was the dam of
several good horses. She may have inherited the x-factor from Robin
Redbreast, the broodmare sire of Sumpter, who sired her dam Rowena. Robin
Redbreast's dam, Wren by Woodpecker, was out of a strongly suspected
carrier, Sir Peter Teazle's dam Papillon, and produced the good filly
Bellissima, winner of the Oaks, the four mile Oxford Gold Cup, and two
One of the most difficult feats a racehorse can
accomplish is to win the Triple Crown. We have already made strong cases for
War Admiral, Whirlaway, Citation, and Count Fleet as x-factor horses.
Secretariat is a known x-factor horse. What of other six?
The first Triple Crown winner, Sir Barton, was a champion
despite the fact that he was never fully sound. Plagued by bad feet, he
nonetheless swept the 1919 Triple Crown and was the best older horse of
1920. His dam, Lady Sterling, was by Belmont Stakes winner and Horse of the
Year Hanover, who is out of Bourbon Belle by Bonnie Scotland. Bonnie
Scotland's third dam is by Whalebone, a son of Penelope, and his fifth dam
is by Sir Peter Teazle. Sir Barton's most notable offspring was the filly
Easter Stockings, and failing to sire anything else of note, he ended up in
Gallant Fox was a big, well made horse, and he proved
himself exceptional by winning not only the Triple Crown, but also the Dwyer
Stakes and the Lawrence Realization. He had two very successful brothers as
well; his full brother Fighting Fox and his half brother Petee-Wrack, who
won the Suburban Handicap. This definitely is cause to accuse Marguerite,
their dam. She contributed the x-factor that allowed Gallant Fox to take
maximum advantage of the speed and power he inherited from Sir Gallahad III.
Marguerite was by Celt, a good son of Commando. Celt was out of an Amphion
mare, and Amphion's second dam was by Rataplan. Incidentally, Sir Barton's
good daughter Easter Stockings was out of a Celt mare.
As for Gallant Fox's son Omaha, he is out of Flambino by
Wrack. Wrack, broodmare sire of Hildene, is out of an Isinglass mare.
Hildene is an extremely strong x-factor suspect, being the dam of Horse of
the Year Hill Prince, the champion colt First Landing, and Satsuma, the dam
of the outstanding Cicada.
If any horse outperformed his conformation, it was the
club footed comet Assault. His sire Bold Venture won the Kentucky Derby, but
Assault's dam Igual had two chances to inherit the x-factor, and therefore
probably passed it to her son. Igual's sire was the great Equipose. Her
second dam was Man o' War's full sister Masda.
Equipose was twice Horse of the Year. Plagued throughout
his career by a chronic quarter crack, he missed the classics as a three
year old, but was a champion at two, four, five, and six years of age. He
carried weight, and won at a distance. His broodmare sire Broomstick set a
track record winning the 1903 Brighton Handicap, and earned a membership in
the Hall of Fame. His second dam was by Epsom Derby winner Bend Or, whose
daughter Fairy Gold produced Fair Play and Friar Rock.
If Bend Or was a carrier, it might be somewhat difficult
to find the source. Much speculation surrounds his dam's identity. Some
claim he was actually out of a mare named Sandiway, and that the mares had
switched foals. A conflicting story claims that it was Rouge Rose who was
switched as a foal, and that she isn't actually out of Ellen Horne.
Regardless, Bend Or's accepted pedigree has him as a son of Rouge Rose, and
assuming that is correct, the source of his x chromosome was possibly
Highflyer. Rouge Rose's dam Ellen Horne is by Redshank, whose broodmare sire
Selim is out of an Alexander Mare, who is in turn out of a Highflyer Mare.
This speculative path accuses Redshank and Selim of being
x-factor horses. This doesn't ring true. Rouge Rose's sire Thormanby is a
more likely suspect. Winner of the Ascot Gold Cup and the Epsom Derby, he
was out of the durable and very successful Alice Hawthorn, whose fifty two
wins included two Doncaster Cups, a Goodwood Cup, and the Ascot Gold Vase.
She was by Muley Moloch out of Rebecca by Lottery. Doncaster Cup winner
Lottery is a suspect, being out of Mandane, dam of several very successful
But back to our Triple Crown winners. Seattle Slew
certainly turned in the type of performances typical of an x-factor horse
who had everything else a champion thoroughbred needed as well. His Kentucky
Derby was impressive. Slew won despite the obvious nervousness he displayed
in the paddock as well as a bad start. As a sire, he proved he had qualities
other than the x-factor, siring champions like Slew o' Gold, Swale, and A.P.
Indy. Granted, Slew o' Gold and A.P. Indy were out of almost definite
x-factor mares, Alluvial by Buckpasser and Weekend Surprise by Secretariat,
and Swale's third dam was by Nasrullah. Seattle Slew's x chromosome may have
come from his third dam, Myrtle Charm by Alsab. We'll get to him in a bit.
My Charmer, the dam of Seattle Slew, had produced nothing
notable prior to Seattle Slew, but once being put to better stallions, she
produced Lomond, winner of the 2,000 Guineas, and Seattle Dancer. Bold
Reasoning sired no other horses of significance.
Was Affirmed an x-factor horse? Affirmed's broodmare sire
Crafty Admiral was out of a War Admiral mare and his third dam was by
Mahmoud, so he had the opportunity. He had outstanding conformation, so with
the x-factor he would have been a superb performer. He won the most hotly
contested Triple Crown in history, and was Horse of the Year as a four year
old as well, so his performance qualifies. While not unsuccessful as a sire,
he has yet to reproduce himself, with his daughters outshining his sons.
Now how about a few of those horses that became champions
despite "modest" pedigrees. Three famous examples from the thirties and
forties spring to mind. Stymie, Alsab, and Seabiscuit. The success of
Stymie, former claimer turned leading money winner, was explained by writer
C.W. Anderson. "Both his sire and his dam were out of Man o' War mares." And
from his second dam Stymie may have inherited the x-factor, and the
increased heart size he gained from that gene would have helped him
accomplish those breathtaking stretch drives that made him so famous.
Seabiscuit, who was so lame he could barely walk, still
managed a career in which he defeated War Admiral, earned Horse of the Year
honors, and won the Santa Anita Handicap, at the time the world's richest
race, at the age of seven. His broodmare sire was Whisk Broom II, who by
sweeping the 1913 Metropolitan, Brooklyn, and Suburban Handicaps became the
first winner of the Handicap Triple Crown. Whisk Broom II's second dam was
by the great Hindoo, who was out of a Lexington mare.
Alsab's dam may once have sold for ninety dollars, but
she probably carried the x-factor. Her dam was a Fair Play mare. Her second
dam was by St. Simon. Alsab, a seven hundred dollar yearling purchase, won
the Preakness and the Belmont, and later defeated Whirlaway in a match race.
A more recent Cinderella horse is the great gelding John
Henry. No one had ever heard of his sire, Ole Bob Bowers, and he had
numerous conformation problems. He was cranky. He was gelded in an attempt
to make him grow. But he was Horse of the Year twice and at one time he was
the world's leading earner. And all that without even starting in a big
three year old race. John Henry's dam? Once Double was by Double Jay, a
successful son of the Whisk Broom II mare Broomshot. John Henry's third dam
was by Mahmoud, whose dam Mah Mahal was by English Triple Crown winner
Gainsborough out of a mare by The Tetrarch, that undefeated legend who was
often described as a freak of nature.
Double Jay may not have been a carrier, although he had
the chance to be, but Once Double certainly proved to be. Her dam had a
double chance to inherit the x-factor, and her son's performance proved
The Tetrarch sired Europe's flying filly, the brilliant
Mumtaz Mahal, whose daughters included Mah Mahal, the dam of Mahmoud, Rustom
Mahal, the dam of Abernant, and Mumtaz Begum, who produced the speedy but
Vahren, the dam of The Tetrarch, was by the classic
winner Bona Vista, whose dam was out of a King Tom mare, but it was just as
likely that The Tetrarch came by his x-factor through the female line. His
sixth dam was by Rataplan.
As for Gainsborough, his pedigree is full of x-factor
suspects, but the only one in the right place to be guilty in his case is
Epsom Derby winner Bend Or, sire of his third dam.
La Troienne was the matriarch of Idle Hour Stock Farm. A
superior mare in every way, she produced quality whether she passed on the
x-factor or not. She produced two champions who became Hall of Fame members,
Bimelech and Black Helen. Her daughter by Bubbling Over, Baby League, was
the dam of Busher, Mr. Busher, and Striking. Big Hurry was the dam of
Searching, Bridal Flower, The Admiral, and Saratoga Cup winner Great
Captain. Businesslike, one of several good daughters by Blue Larkspur,
produced Busanda, who won the Alabama Stakes, the Suburban Handicap, and two
runnings of the Saratoga Cup. Even more notably, Busanda was the dam of the
great Buckpasser. La Troienne also produced Big Event, Bee Ann Mac, Belle
Histoire, Belle of Troy, and Besieged.
Searching produced the outstanding daughters
Affectionately and Priceless Gem. Affectionately was a champion herself, and
produced Horse of the Year Personality. Priceless Gem was also successful on
the track, winning the 1965 Futurity, but was better known for producing
Allez France, the brilliant winner of the 1974 Prix de l'Arc de Triomphe.
Affectionately was very possibly a homozygous x-factor
horse, being by Swaps. His second dam was by War Admiral, so Swaps had the
opportunity to inherit the x-factor, and he overcame many difficulties to
not only win the 1955 Kentucky Derby, but also to become the 1956 Horse of
the Year. After racing with a quarter crack, Swaps was out of action for six
months following his match with Nashua, and when he did return to the track,
Swaps still wasn't sound. Racing on three legs, the brave horse carried as
much as 130 pounds to victory in eight races, setting four world records and
equaling another before his life was threatened by a severely broken hind
Swaps' rival Nashua himself may have been an x-factor
horse. He was an exceptionally talented horse, but along with his sire's
brilliant speed, he also inherited his tendancy to sulk. Nasrullah, a
champion at two, was unsuccessful in the classics not due to lack of
ability, but rather due to his refusal to run when asked. Nashua was better,
but his riders rarely knew whether or not the horse would run his race.
Nashua's broodmare sire Johnstown was out of La France by Sir Gallahad III.
Sir Gallahad's second dam was Concertina by St. Simon. In the conformation
department, Johnstown was something less than perfect, but he proved his
ability to run nevertheless, winning the Kentucky Derby and Belmont Stakes.
At stud, he managed to sire a mere six stakes winners, yet was a leading
broodmare sire. His broodmare sire Sir Gallahad III, both an outstanding
sire and an outstanding broodmare sire, was America's leading broodmare sire
from 1943 through 1952.
The fabulous mare Dahlia, who handed defeat to top class
colts on both sides of the Atlantic before producing four grade I winners as
a broodmare, was by 1968 Prix de l'Arc de Triomphe winner and "Horse of the
World" Vaguely Noble, and her third dam was by Gallant Fox.
So, this could go on for a week, but what good is all of
this speculation about the x-factor? If nothing else, it is a delightful way
to pass the time, and a good excuse to reminisce about the deeds of champion
thoroughbreds throughout history.
Make your own accusations. See if you can make them
stick. Who knows, perhaps your musing, when applied to a yearling sale
catalog, will land the next Seattle Slew in your barn.
Lynn K. Joris hosts The
Unofficial Thoroughbred Hall of Fame
Here is a Genetic Review of what stallions and dams contribute to their
Sex Linked Genes
and the horse
that are inherited in a sex linked manner is different from linkage in which
genes that sit close together on one chromosome are passed on to the next
generation as a combination during the formation of egg and sperm.
large X chromosome (which carries a lot of genetic material that is not
related to reproduction) and mitochondria DNA are inherited in a known
pattern, as is the male Y chromosome (which carries very little additional
material). The Y chromosome consists largely of repeated degraded copies of
x linked genes.
is the vital to learn. Without understanding how sex linked genes are
inherited very little of what follows will make a great deal of sense.
The X trail
passes on an X chromosome to all her foals; a stallion passes an X
chromosome only to daughters.
stallion passes this to all his sons. A mare doesn’t have a Y so she has
nothing to pass on to any offspring.
passes this genetic material on to all her foals. Although stallions have
this material they do not pass this on to any offspring. Similar to Y
inheritance except goes to both male and female offspring.