I started out horses following and learning about the Thoroughbred.
I still can look at a pedigree and get a good idea of what that horse is even tho I do not know the modern studs.
Remember too, that both these photos you have here are of young horses.
The upper photo appears to be a yearling (a hammer headed yearling at that).
If you look at his front end it is realy very good and he has roomy hocks.. but this baby needs to frow and,
if he is going to a yearling sale he needs some weight (fat hides things... on ppl too!!).
If the horse is racing at the time of this photo it appears he is being 'brought up."
The lower photo is of a horse in racing form.. and while fat and letting down won't change his steep croup (which may be steeper due to the water being cool) or his set back somewhat straight hind leg (this started to become a Thoroughbred conformation trend when I was a teenager.. it seems to have carried forward).
Scretariat was a horsemans horse and his racing photos show him leggy. His breeding farm photos he is too fat (but note he has the same throatlatch as our black horse, Lonhro
and the same throatlatchon Man O War.. so there may be some truth to the airway passage theory).
I also had read somewhere that Secretariet's heart was roughly 1/3 larger than the normal horse heart.
It was believed that part of his ability to run, and win, at such distances, had to do with his ability to pump blood more efficiently.
In the fall of 1989, Secretariat was afflicted with laminitis
, a painful and often incurable hoof condition.
When his condition failed to improve after a month of treatment,
he was euthanized
on October 4 at the age of 19.
Popular both as a Triple Crown champion and in retirement, Secretariat was mourned by millions and buried at Claiborne Farm
in Paris, Kentucky
given the rare honor of being buried whole; usually only the head, heart, and hooves of a winning race horse are buried,
and the rest of the body is cremated.
revealed that his heart
was significantly larger than that of an ordinary horse.
An extremely large heart is a trait that occasionally occurs in Thoroughbreds, linked to a genetic condition passed down via the dam
known as the "x-factor."
The x-factor can be traced to the historic racehorse Eclipse
who was necropsied after his death in 1789.
Because Eclipse's heart appeared to be much larger than other horses, it was weighed, and found to be 14 pounds (6.4 kg),
over twice the normal weight.
It is believed Eclipse passed the trait on via his daughters, and pedigree research
verified that Secretariat traces in his dam line to a daughter of Eclipse.
In the 20th century,
the heart of Phar Lap
was weighed and also documented to be 6.35 kilograms (14.0 lb),
or essentially the same size as that of Eclipse.
At the time of Secretariat's death, the veterinarian who performed the necropsy,
Dr. Thomas Swerczek, head pathologist at the University of Kentucky,
did not weigh Secretariat's heart, but stated, "We just stood there in stunned silence.
We couldn’t believe it. The heart was perfect.
There were no problems with it. It was just this huge engine."
Later, Swerczek also performed a necropsy on Sham, who died in 1993. Swerczek did weigh Sham's heart,
and it was 18 pounds (8.2 kg).
Based on Sham's measurement, and having necropsied both horses,
he estimated that Secretariat's heart probably weighed 22 pounds
or about two-and-a-half times as large as that of the average horse".