I can not think of a more beautiful example of form equaling function than to watch a dressage horse perform an extended trot. If the horse is conformationally correct in the slope of his shoulder (and is properly trained) the front leg extends like a ballerina's graceful outstretched hand. Just as the ballerina's stretch extends through the very tips of her perfectly poised fingers, so too the extension in the dressage horse stretches down through the toe of the hoof which gracefully flips forward and lands softly with energy and impulsion exploding into the next stride.
This same extension is what stretches out a thoroughbred down the track, reaching for every fraction of an inch the hindquarters can propel him to. The horse with a proper slope to his shoulder is fluid in his motion and his gaits are comfortable to ride.
The slope of the shoulder is not difficult to find. Follow the line of the shoulder from withers through point of shoulder (the furthest point forward at the end of the shoulder bone, or scapula). Then draw a straight line either along the underline of the horse or on the ground. The angle formed where these two lines meet should be about 45 degrees. The straighter the shoulder line, the wider that angle will be.
Horses are said to be "straight in the shoulder" when this angle is over 45 degrees. The conformation in the shoulder is normally mirrored in the slope of the pastern (the skinny part of the leg between the leg and hoof) which should also be about 45 degrees. The shoulder and pastern act like shock absorbers. When a horse is straight in the shoulder and pastern his gaits are very short and choppy. Not only is he not as comfortable to ride, but the constant jarring can be damaging to him. The most serious complication that such a horse is predisposed to is a hoof condition called "navicular." We will discuss this condition more fully in another issue that will be dedicated to the hoof. In brief, it refers to the degeneration of the navicular bone inside the hoof.
A "sweeny" is an unsoundness located in the shoulder area. It is a degeneration of the muscles on either side of the scapula caused by nerve damage. The bone will appear very sharp and pronounced as the muscles on either side atrophy. When the horse walks, he will swing the leg on the affected shoulder out to the side. You may also hear a popping sound. This action is referred to as lateral slippage and may be apparent long before the muscles show the signs of atrophy.
