CRUCIAL CONFORMATION

Part 1: An overview

When choosing or evaluating a horse, there are many factors to consider: breed, breed type (how the horse embodies the characteristics of his breed or type), pedigree, colour, temperament and personality. However, the most important element is the conformation, particularly if you want the horse to have an athletic career or breed. Choosing a horse based on an understanding of conformation makes it less likely that you will endure the disappointment or heartbreak of a career-ending injury or early loss of use due to arthritis or injury.

A horse with good conformation has no apparent faults that detract from his general appearance and function. Crucially, however, conformation is not just about looks but also about suitability for the job the horse will be asked to do. Some of the 'rules' of conformation are based on pure physics – structural strength, leverage forces and proper angles, for instance – and these help us understand why some horses stay sound and others do not.

Of course, some horses with poor conformation go on to be winners, but these are truly the exception to the rule. Most of the best equine athletes possess certain qualities of good conformation that enable them to perform at a higher level. Generally, the horse with good conformation and proper body and leg angles experiences less wear and tear on joints and other structures. He is more apt to stay sound and perform well during a long life of athletic service than a horse with serious conformational flaws.

Unsoundness

Poor conformation predisposes horses to certain unsoundness issues. For example, some conformation types can make a horse more likely to develop ringbone, sidebone, splints, and navicular syndrome.

Injuries from accidents are responsible for some types of unsoundness, such as blindness due to a kick to the eye or sidebone due to an injury. These obviously are unrelated to the horse's conformation and far more related to temperament and just plain luck! Other types of unsoundness, such as a bowed tendon, bucked shins and certain splints, can result from excessive strain and overwork. Problems like this, which are caused by strain and trauma, tend to occur more readily and be more severe in a horse with poor conformation.

An unsoundness can be mild or severe, depending, to some extent, on the horse's function. For example, a bowed tendon or ringbone may stop a jumper in his tracks but may not be an issue for a pleasure horse or happy hack.

Form follows function

When breeding or selecting horses for specific purposes, we must have a good eye for the aspects of conformation that promote soundness and enable a horse to excel in what we are looking for him to do.

When evaluating a horse, it's essential, therefore, to consider his conformation and how it affects his health, soundness and ability to perform his job. To understand how the horse moves and to evaluate his chances for athletic success in a specific task or sport, we must have a basic understanding of equine anatomy, especially the horse's skeletal and muscular systems. You can more easily envisage how the horse's skeletal system functions when you realise that nearly every part of the horse's body (except the tail!) corresponds to a similar part of the human body. Similarly, the only anatomical feature humans have that horses do not have is the clavicle or collar bone.

Comparative Anatomy

Front Legs

The bones of the equine front leg are similar to those of the human arm and are arranged in the same order: the shoulder blade (scapula), humerus (upper arm), and radius and ulna in the forearm. There are only a few minor differences. The two lower arm bones (radius and ulna) are fused together in the horse, and the ulna is smaller, but the upper end remains as the point of the elbow. In humans, the two arm bones are separate but parallel to each other, with some connecting tissue between them. This allows the human forearm to rotate at the elbow, whereas the horse's forearm cannot rotate. Thus, in the horse's front leg, the knee, which is equivalent to the human wrist, must move forward in a straight line.

Another difference is that the human arm is free moving and independent from the shoulder joint downwards, whereas the horse's humerus, equivalent to the arm bone, is attached to the chest wall but with skin and very strong muscles. This gives it a much more limited range of motion, as it is encased in the overall 'body' of the horse.

Hindlegs

In a horse's hind leg, the femur (the upper leg bone or thighbone) is also bound to the body by muscle and skin. This gives the impression that the horse's hind leg begins at the stifle, just as you might think a horse's front leg starts at the elbow, but it actually begins where the pelvis joins the spine. The bones and joints of the equine hind leg are similar to the bones and joints of our leg. The horse's stifle has the same structure as the human knee, with the patella or kneecap present in both.

Knees and hocks

The horse's front leg is like the human arm, with the equine' knee' corresponding to the human wrist, and having the same seven bones in identical arrangement: six small flat bones in two rows, with the seventh bone, the accessory carpal bone, standing out at the back of the horse's knee, as does the small prominence at the back of the human wrist on the inner side. The horse's hind leg compares to the human leg, with the hock joint corresponding to the human ankle and having the same seven bones. The point of the hock is similar to the human heel, and both have an Achilles tendon. The strong muscle above the hock is similar to the human calf muscle.

Lower leg

The cannon bone, front and rear (below the horse's knee or hock), corresponds to the human middle finger or toe, and the fetlock joint is equivalent to the middle knuckle on that finger or toe. The horse's hoof is like the tip of our middle finger. The horse's hoof wall grows from the coronary band in the same way our fingernails grow. A human has five fingers and toes, but the horse only has one central 'finger' and two reduced digits on either side of it. These digits are the splint bones that go partway down the cannon bone, leaving the enlarged middle bone (cannon bone) to bear the horse's weight. These small splint bones partially support the knee joint, but the large, strong cannon bone (third metacarpal) is the main support. In the hind leg, the cannon bone compares with the middle toe, with the hock joint also partially supported by the smaller bones (splint bones) alongside it.

Chest

The rib cages of horses and humans have similar bones, although the chest shapes differ. The thorax (chest) of the horse is flatter from side to side, and the shoulder blades move back and forth along its sides. The human chest, on the other hand, is flatter from front to back, and our shoulder blades move at the back of our rib cage. The horse's chest is also much deeper from breastbone to spine, and the horse has much greater lung capacity and endurance than a human.

Head and neck

The horse's neck is longer and more mobile than the human's but has the same seven bones. The horse's heavy head allows him to use his neck as a pendulum, swinging it up and down or side to side to shift his balance. His long neck also helps him to reach the ground when grazing and scan the area for predators or other threats.

Some key definitions

Blemish: A visible lump, thickening or scar. A blemish is not considered an unsoundness unless it interferes with a moving part or the ability of the horse to work or has the potential to cause lameness with hard work. A blemish is NOT a fault of the horse's conformation. It might be a healed splint, windgalls or a scar.

Conformation: How a horse's body is put together; specifically, his body shape, the configuration of the body parts, the relationship between those structures, and how they function. Conformation determines how a horse moves and how well or poorly his body can withstand the effects of work.

Fault: An undesirable conformation aspect, such as sickle-hocks, pigeon toes or a short neck. Sometimes, a fault may lead to unsoundness if the horse is worked hard.

Sound horse: A healthy horse with no injuries or impairments.

Unsound horse: A horse with a physical injury or abnormality that interferes with his usefulness.

Unsoundness: Anything that makes a horse lame or unsafe to ride, impairs the stamina for work, or otherwise makes him unable to perform normally.

Take home message

Conformation is a vital consideration when choosing a horse. Unfortunately, this seems to have fallen out of favour in recent years, with many equine shoppers looking solely at the performance or bloodlines of the horse rather than his potential for longevity. In this series, we will be looking at the key aspects of conformation that are important to bear in mind when choosing your next equine athlete.