| Conformation is a term to describe a horse’s anatomical makeup relating to its specific function. For example, Quarter horses are anatomically built to work at high speeds for short distances while Thoroughbreds are bred for high speed and long distance. Whether purchasing or breeding horses, it is important to decide beforehand what the intended use of the horse will be and whether or not it has the right conformation for the chosen discipline. In addition conformation is used to help predict future lameness issues and can be helpful in guiding lameness diagnosis. This article will discuss some common conformational issues and introduce the concept of how these can relate to lameness. This is an enormous topic and is only discussed briefly here. Conformation is mainly a heritable trait although nutrition, environment, and hoof care play a role as well. Horses have been bred for thousands of years to encourage the expression of conformational characteristics that improve the use of certain breeds.
When evaluating conformation, it is important to look at the entire horse. According to Ross in Diagnosis and Management of Lameness in the Horse, conformation evaluation has four components: 1) balance, 2)assessment of lengths, angles, and heights, 3)muscling, and 4)conformation of the limbs. Each component is judged separately and then put together for an objective assessment of the whole horse. It is essential to assess the animal on a hard flat surface with the horse standing squarely.
One can look at the balance of the horse by dividing the body into thirds; the forehand, the mid-body, and hindquarters. The more correctly proportioned horses are generally better athletes. Excessively long or short backed horses may have problems with their backs and/or hind limbs. In addition the withers and the rump height should be equal. Horses with higher rump height may have more issues with forelimb lameness. Proper body length can be determined by measuring the distance from the point of the shoulder to the rump. This distance should be equal to or slightly longer than the withers height.
Shoulder and croup or rump angles are important to look at as well. Horses with longer flatter rumps should have longer strides while short steep croup angles could increase the chances of hind limb lameness. Shoulder angles should be around 45º. Steeper angles may result in decreased shock absorption and therefore increased forelimb lameness.
As stated earlier, to evaluate the legs properly, the horse must be standing on a level surface, standing square. It is easy to misjudge a conformational defect if the animal is not positioned properly. When viewed from the front of the horse, an imaginary plumb line drawn from the point of the shoulder straight down should divide the front legs into two equal halves. If the hoof is on the outside of the imaginary line they are called base-wide, and if on the inside they are base-narrow. Each of these may be accompanied with a toed-in or toed-out conformation where the hoof turns to the inside or outside respectively. Horses with these defects have a list of potential lameness and hoof wear issues that must be dealt with accordingly including lower limb arthritis, strains and sprains, and interfering.
When viewed from the side, a plumb line drawn from the elbow joint should bisect directly through the knee and fetlock joints. Abnormalities in this area can cause tendon and ligament strain, joint injuries, and navicular syndrome.
Hind limb conformation can be the most difficult to judge. Viewed from the side, a plumb line drawn from the point of the rump to the ground should touch the back of the hock and be in line with the canon bone. From the back, a line drawn from the point of the rump should divide the hock and fetlock through the middle. Horses that are mildly turned out in the hind limbs or slightly cow-hocked are common and don’t typically have lameness associated with this conformation defect. More severe abnormalities can put extra tension on the hocks, hips, and fetlocks resulting in arthritis or injury.
The angle of the pastern should roughly be the same as the angle of the shoulder. Steep pasterns have little shock absorption and low pasterns have poor tendon and ligament support. The pastern angle should be in line with the hoof angle when viewed from the side. A “broken back” or “broken-forward” pastern-foot axis can lead to uneven load distribution and potential coffin bone or navicular bone problems as well as tendon and ligament strain.
This is by no means a complete review of conformation, but hopefully it introduces a few concepts to guide you in horse purchasing, breeding, or general maintenance of your horse. The charts are taken from Mike Ross’ Diagnosis and Management of Lameness in the Horse. They illustrate some of the issues discussed
Copyright © 2009 The NW Horse Source, LLC
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