Each thoroughbred horse is an individual. The five common descriptors used to distinguish one horse from another are:
At any moment a racing fan can obtain detailed information about any given horse, in four different categories of information: Physical condition (related to the horse's anatomy); Pedigree (the horse's genealogy); Performance history (a carefully documented chronicle of each horse's races throughout his career), Personality (mainly attitude).
Racing fans can evaluate a horse's physical condition from handicapping notes and articles and from personal observation.
Understanding equine anatomy is essential to interpreting this information. These are the fundamentals of equine anatomy: A "hand" is 4 inches. Most race horses are from 14 to 17 hands (measured from the ground to the withers, which is the area at the base of the neck, where the shoulders, back and neck meet). Secretariat was 16 hands 2 inches tall, which translates to five and a half feet, foot to withers.
The strength of a horse comes mainly from its rear legs, thighs and buttocks. The rear leg bends the opposite way from a human knee, and the vocabulary for the rear leg is different from human anatomy.
The "gaskin" is the upper portion of the leg (like our thigh); the "cannon" is the area between the middle joint and the ankle (like our shin); the "hock" is the mid-joint (like our knee); and the "fetlock" is the lower joint in the rear leg (like our ankle). In addition, the "pastern" is that indented area behind and above the hoof, and the "coronet" is the crown area above the hoof in the front. "Ankle" and "knee" are used to describe the two joints on the horse's front legs, which flex in the same way as human legs do. These terms may be employed in any write-up about a horse's condition, as well as the other terms, like abdomen, which are fairly obvious.
Pedigree is also important to horseracing. The "sire" is the horse's father. The "dam" is the mother. The mother's father (called the "grand dam") is also listed when the animal is described in the handicapping materials. There are two related reasons why pedigree is considered important. One is the inheritance of physical, genetic traits like strength in certain bones, resistance to certain unhealthy conditions, stature, stamina and inherent speed.
Considered even more important at times is the inheritance of traits not identifiable by physical inspection, like the desire to win (competitiveness) and discipline (the ability to focus and to trust a rider). A good race horse is spirited, but not undisciplined. While the jockey and trainer are instrumental in molding this aspect of a winner, much of the emotional and spiritual talent of the horse is bred into him (or her).
Once more, Secretariat a good example here. Of the 653 foals he sired, 57 were stakes winners.
The Racing Form and a couple other sources of information provide very detailed statistics about how a horse has performed in every race of his career, including details on the competition, and how the horse was doing at different moments of the race. The data includes a description of the track and the race in each case, as well as the name of the jockey and the equipment used.
Personality is sometimes commented on in the documentation, but this almost intangible characteristic is left largely up to the racing fan to infer from the other information (like pedigree and performance history) and from personal observation of the horse at the track or in the video feeds.
Sometimes a horse will be described as "having class." Other times, it may be commented that a horse was "outclassed" in a race.
This term refers to a combination of factors that cause a horse to be considered good material for any given level of racing, often the top categories.
"Class" means a pedigree of champion horses, combined with a personality as a youngster that shows spirit and discipline for training, and a capacity to win. Such a horse "has class." The ambition of the trainer and of those who compose the line-up for races is to have the horse compete where his (or her) "class" (or lack of class) would indicate as appropriate.