The way a horse is built has a significant effect on how the feet and legs deal with the impact of runningThe impact of a horse's feet and legs upon the ground as he travels is one of the major causes of lameness and unsoundness-either directly or indirectly. Horses that have good conformation, with feet and legs that distribute concussion equally to all parts, are less apt to become lame with hard use. The muscle and skeletal arrangements of the better performance horses are remarkably alike, regardless of breed; these are the horses that can best handle the stress and strain of athletic exertion. Their bodies are shaped to absorb and distribute concussion so that no one part suffers undue wear and tear.
The horse is a heavy bodied animal for the size of his feet. He has much less ground surface for the weight of his body than does a human. The impact of a horse's weight times his speed creates a tremendous amount of concussion on those few square inches of hoof. How well a horse holds up under this kind of trauma to feet and legs is the primary factor determining the length of his useful life. The horse's front legs are subject to more concussion than the hind legs, since about 65% of the horse's weight is carried by the front legs (due to the head and neck). This is why many types of lameness are more common in front legs and why conformation faults are generally more serious in front legs than in hind legs.
Concussion is countered by several factors, including the way a leg is built and the way it moves, distributing impact through a number of different structures. Poor conformation always put added stress on certain parts, which may eventually lead to breakdown, lameness, and/or unsoundness. The more nearly ideal the leg and joint conformation, the more uniformly the stress will be distributed and absorbed.
movement within the compound joints of knee and hock, the pumping action of the foot, and the springy action of the fetlock joint are the main shock absorbers in the leg. A horse must have proper length of bone and proper angulation between the bones for ideal motion and ability to withstand concussion. Joints should always be large and well defined, not small and pinched up.
The traveling horse is subjected to a lot of concussion, transmitted to his body through feet and legs, but several factors work together to overcome the effects. In the front leg, the foot expands and the plantar cushion(frog) acts as a buffer. The pastern "gives," transferring strain from the leg bones to the more elastic tendons. If the pastern is too upright, more concussion is transmitted directly to the bones. The shoulder blade glides over the ribs and transfers any remaining shock (not taken up by the pastern) to the body muscles.

The knee
Front legs suffer the most concussion not only because of the extra weight they carry but also because of the way the knee and elbow joints are constructed, making the leg a solid column whenever weight is placed on the foot. The knee absorbs some concussion in its two rows of overlapping flattened bones (seven bones, just like in the human wrist), arranged in two rows between forearm and cannon bone. Each little knee bone is separated from those around it by a layer of cartilage, as well as synovial membranes that lubricate the gliding surfaces. Thus, the bones can move a little upon each other and absorb some of the force traveling up the leg.
But the knee cannot flex like the hock does; when taking weight, the knee must remain extended and rigid. In the front leg, the pastern alone is able to yield, to absorb the impact transmitted upward from the foot. Thus, a horse with a long, sloping pastern has more give and more concussion-absorbing ability than the horse with a short, steep pastern, usually holding up better under hard use than the choppy striding upright horse that hits the ground with more jar.
The fetlock joint has a great degree of movement and is supported by the flexor tendons and suspensory ligament. The pastern joint (between the long pastern bone and short pastern bone) has little movement and minimum amount of concussion absorption (perhaps one reason it is subject to problems such as ringbone). The coffin joint inside the foot has more movement and elasticity because of the way the navicular bone is placed and its pulley action with the flexor tendon. Direct concussion to the coffin joint is avoided by transferring some of the weight from the short pastern bone to the navicular bone, and from it to the coffin bone. The navicular bone is well supported by the deep flexor tendon behind and below it.
The knee supports weight only when fully extended (front leg straight) and the elbow joint is locked, making the leg a solid column except for the pastern. The force then travels up the leg to the shoulder joint and hence to the shoulder blade. A small degree of flexion is produced by the shoulder joint (you can see the point of the shoulder drop slightly when the front foot lands) but it is the shoulder blade that gives the main buffering effect.
The body is slung between the front legs by means of muscle attachments holding the shoulder blade to backbone and ribs. The shoulder blade is loosely attached to the ribs by fibrous tissue. muscular attachments are somewhat flexible and stretchy, absorbing some of the concussion that would otherwise be thrown upon the skeleton. The flat surface of the shoulder blade can glide upward and backward over the ribs when weight is taken, and this gliding action protects the body from excessive jarring. The more upright the shoulder blade, however, the shorter it is with less gliding action and less shoulder joint flexion. A horse with upright shoulders and pasterns transmits more jar to the horse's body (and to the rider) as well as to the legs.

The hind legs
In the hind leg, the flexible hock joint, accompanied by stifle action and flexion, absorbs most of the concussion. There is not the degree of movement in the hock bones as in the knee bones, but this is not crucial since the partial flexion of the hock diminishes concussion.
In front, the body is suspended between the forelegs; there is no bony attachment. But in the hindquarter the pelvis is attached to the backbone at the sacrum, which is capable of only very limited movement. Thus, any concussion not absorbed by the hind leg is transferred to the backbone and has to be taken up by the disks between the vertebrae. If these have already suffered from jarring and overcompression or have become fused due to concussion and inflammation (and subsequent calcification), any buffering effect will be gone, leading to a painful back.
Extra concavity of the sole of the hind foot helps diminish effects of concussion; there is more give to the sole. The horse's foot works best at counteracting concussion when the foot is of proper size and shape with strong, deep heels. The hoof wall expands when weight is placed on it, the rear parts spreading and the fibrous tissue above the frog compressing and expanding outward as the foot takes weight. Thus, the concave sole flattens and descends as the foot takes weight. Frog and sole movement in a normal, healthy foot are instrumental in reducing concussion.

Distribution
To better distribute the weight and impact of traveling at fast speeds, over jumps, etc., the horse uses several mechanisms to maneuver without hurting himself. He can change his center of gravity very quickly by raising or lowering his head, and can flex his hocks and take more weight on the hind legs, freeing the fronts. He can, in turn, gather his weight back off the front legs when stopping quickly.

Weakest links
The long pastern bone and the navicular bone are perhaps the weakest links in the structure. But the unique arrangement of tendons and pulley blocks created by the sesamoid and navicular bones make very little direct strain upon the pastern bone if the horse has a good sloping pastern. Short, steep pasterns (and feet too small for the weight of the horse- too small to distribute concussion) put more strain on these bones. Extra weight and pressure is also put on the navicular bone if the horse gallops uphill or has long toes and low heels.
No two horses are built alike and it is not easy to tell which horse will hold up under hard use and which will break down, just by looking at conformation. There is another factor involved; for want of a better term we will call it structural integrity-the strength and soundness of the stay apparatus and all other factors that hold joints and bones together. This is as crucial as good conformation, for without it a horse will not hold up.
Some horses with serious conformation faults still manage to hold up well after years of hard use on the racecourse, hunt field, endurance rides, or other strenuous careers. These horses have structural integrity, the "good leather" that holds them together and enables them to stay sound and perform well under the handicap of imperfect leg structure. When judging a horse, one looks at conformation and guesses at durability. Most horses with poor conformation do eventually break down from the stress of concussion if used hard but there are always exceptions-the few who fool you because they have the strength of structure to hold together in spite of the odds against them. But, as a general rule, it is a safer bet to go with the well-constructed horse, since good conformation is more conducive to athletic ability, proper function, and longevity. Good feet and legs are more apt to stay sound, since they can handle concussion.


An old Chinese treatment attracts new interest
The new age of technology has caused some horsemen and veterinary practitioners to look to the past to treat everything from colic to back pain to acute and chronic injuries. The ancient art of acupuncture is enjoying a resurgence these days as horsemen seek treatments that work without inadvertently causing post-race positives. Now horsemen can add another classic Chinese treatment method to their arsenal-herbal therapy.
At a recent seminar conducted in Lexington by holistic veterinary practitioners and their herbal products manufacturer, Thousand Mile Chinese Herbal Formulas, some 80 veterinarians, horsemen, and other interested parties heard about the benefits of Chinese herbal therapy, which its practitioners laud for its effectiveness without the side effects like those caused by steroids.
The seminar-which was held at the Gluck Equine Research Center in Lexington and featured presentations by Joyce Harman, D.V.M., Chinese herbal expert Jake Paul Fratkin, and Huisheng Xie, D.V.M.-introduced its participants to the "new" vocabulary of Chinese medicine, which describes the primary aspects of herbs in terms of temperature, energy direction, and taste. Therapists operate from a basic catalog of some 350 substances-mostly plants but also some seashells and animal parts-that are combined in specific formulas for specific treatments.
Acupuncturists and Chinese herbal therapists say that getting Western hardboots to overcome differences in the vocabulary and philosophies of Eastern medical practices has been the hardest part of their job. But as drug testing sensitivity increases and the nationwide New Age trend for holistic therapy extends into equine health care, even hardboots are taking a second look.
Although few are used to thinking of equine ailments in terms of energy blockages, excess cold, or stagnant blood, the Gluck Center's Dr. Tom Tobin-a self-described "mainstream pharmacologist"-noted in opening the June 15 seminar that the roots of his specialty clearly are based in herbal remedies. But unlike Western medicine, Fratkin added, Chinese herbal therapy is based on using substances and procedures that are not necessarily aimed at a particular symptom; rather, under this ancient modality, the therapist focuses on the horse's entire system and environment.
Still, most proponents of traditional medicine agree that Chinese herbs-which are imported from mainland China or Hong Kong and can be administered as feed supplements or topically-are not the only path to enlightened treatment. Fratkin noted that Western medicine often is best for "crisis intervention" against life-threatening situations, while traditional Chinese treatments are more useful-and often less harmful-than Western medications in dealing with chronic problems, degenerative disorders such as arthritis, and stress-related problems. And Harman encourages horsemen and veterinarians alike to throw off cultural blinkers and use both systems in complement when seeking treatments for their horses.
-Glenye L. Cain