NEWS
Front end soreness: the foot
Posted: Saturday, August 12, 1995
Many of the problems related to front-end soreness of horses can be tied to the feetAS horses move, there is a tremendous concussive force exerted upon their feet, limbs, joints, muscles, and tendons. Several factors that work together may cause any one or a combination of these structures to become sore or injured. As a result of an injury or soreness, a horse's way of going, willingness, and ability to work, go to the paddock, load in the gate, and race may be adversely affected.
There are many factors that may affect a horse's physical soundness. They include the horse's age, conformation, shoeing, conditioning, gait, speed, stride length, appropriate tack and its fit, handling, footing, and the actions of the people on and around the horse. Any one or a combination of these factors may cause a horse to become sore or injured.
A primary problem that develops in one joint or leg may lead to a secondary injury or soreness elsewhere in the same leg or in another limb. This secondary problem occurs as a horse attempts to ease its pain and discomfort from the initial injury by compensating and altering its way of going. Often the compensatory secondary soreness that develops is more of a problem for the horse and trainer than the initial injury or soreness. Specific injuries and soreness can alter a horse's gait in characteristic ways. However, the slow development of a primary problem or the occurrence of one or more secondary injuries may obscure the early recognition and subsequent treatment of the initial injury.
Recognition and identification of musculoskeletal problem areas of a horse may be done by a variety of examination methods and techniques. In some instances, a horse's way of going is all that is needed to localize the sore area. The other extreme that may be encountered is the need for an in-depth, time-consuming lameness examination with auxiliary tests and diagnostic equipment. The end result of any type of lameness exam, however, is the same: the identification of injured or significant sore areas. Once an area is localized, steps are taken to determine the extent and severity of the injury so a prognosis can be made and appropriate treatment started.
A balanced foot
A horse's head and neck weigh approximately one-fifth of the horse's total body weight and act as a balancing beam. About two-thirds of a horse's weight is distributed over its front legs because of its conformation and forward center of gravity. If a horse's foot care and conformation is adequate, the stress and concussive forces associated with training and racing are more equally distributed throughout the support structures of the front legs, hind legs, and body.
Everyone talks about the importance of a balanced foot for a horse. This is important. Of equal importance and often overlooked is the hoof-pastern axis as viewed from the side. This axis refers to two imaginary lines running through the hoof and pastern. One line runs down the center of the pastern and the other line is drawn up the front edge of the hoof. The two lines should be parallel. When they are, the weight of the horse will be transferred down the pastern column to the center of the hoof. This provides the most efficient and effective method for weight distribution. Even with horses that have steep or sloping pasterns and shoulders, the hoof-pastern axis will be parallel when the feet are properly trimmed.
A broken-back hoof-pastern axis occurs when the two lines converge and the line of the hoof tilts to the rear. This is frequently seen when the toes are too long or the heels are too short. The weight of the horse is then transferred to the heel and navicular region of the foot, causing soreness. This is mistakenly done in an attempt to increase the stride length of a horse. A broken forward hoof-pastern axis is also possible, but much less common. Any abnormal hoof-pastern axis predisposes a horse to additional problems farther up their legs.
The hoof can be involved in a number of abnormal conditions. The more common abnormal conditions include sole bruising; subsolar abscess; thrush; hoof wall cracks at the toe, quarter, or heel; long toe and underrun heels; seedy toe; contracted heels; corn; navicular syndrome; laminitis (founder); pedal osteitis; and coffin bone fracture. These conditions often contribute to or are the underlying cause of serious problems higher in the leg.
Underlying disease
Contracted heels are often symptomatic of some underlying disease or improper shoeing. Seedy toe is due to a hollow hoof wall where there has been a loss of hoof substance at the horn of the toe for a variety of reasons. Corns are a trauma-induced painful condition of the insensitive and sensitive tissues of the sole usually at the angle of the bar and wall.
Navicular bursitis/navicular disease begins as a bursitis due to increased pressure on the navicular bursa by the deep digital flexor tendon. The bursitis can progress to degeneration and erosion of the navicular bone. Laminitis involves inflammation of the sensitive laminae of the hoof. The clinical effects may range from sore, warm feet to rotation or sinking of the coffin bone, while pedal osteitis is associated with inflammation and changes of the coffin bone. The inflammation and increased blood flow causes rarification of the coffin bone due to calcium loss.
The foundation of a horse and its athletic career depend upon a solid and balanced foot with a proper hoof-pastern axis. The achievement of an appropriate foot balance and straight hoof-pastern axis is dependent upon the evaluation and subsequent trimming of each individual horse. There is not one set preconceived angle that every horse should mimic. The hoof-pastern axis will be straight when a horse is appropriately shod. The concurrent hoof angles will provide the straight hoof-pastern axis and they will vary with each horse. Such a solid foundation decreases limb trauma and the degree of soreness that develops from the repetitive stresses of athletic performances.
Brad J. Gordon, DVM, specializes in surgery, lameness, and therapeutics in the Midwest and Caribbean.
