Gait is the muscular action of the horse, or different sequences in which the horse's feet touch the ground. Gait abnormality is commonly associated with pain and/or restriction of movement. For example, restriction of movement occurs when scar tissue limits normal joint motion. "Poining" of front foot indicates pain in the limb, usually the heel area. "Pushing back" with weight on heels indicate pain in the toe area. Stiff, stilted action ("pottery gait"), short stride indicates pain in both front legs. Short stride, difficulty going back is a sign of pain in both hind legs. Some gait abnormalities result from poor conformation.
In many cases abnormal gait can point to specific health problems. Assessment of gait usually takes into account every aspect of gait, such as length of stride, whether too long or too short. Careful observation of the horse's gait can simplify the diagnostic process. In general, the horse with a musculoskeletal problem has irregular gait. That is, the horse may take an abnormal step, or have an abnormal placement; however, the abnormality is the same from step to step. In contrast, the gait pattern in a horse with a neurologic disease is different. The foot placement or step will vary from one step to the next. If local anesthesia resolves the previously identified gait abnormality, then musculoskeletal disease must be the cause. 1
Certain conditions cause a distinctive gait abnormality. In some cases it is so characteristic that a diagnosis can be made just on the abnormality alone. For example, in spinal cord disease, interruption of nerve impulses can cause incoordination (ataxia), stiff-legged or high-stepping action, and weakness. In fibrotic myopathy the horse is unable to swing the affected hindleg as far forward as normal, and so plants the foot down early, in an abrupt manner. 2
Sometimes the horse seem to be reluctant to put weight on its heel, so it is taking short steps and landing toe-first. It appears as if the horse is guarding its shoulder joint by not allowing the normal range of movement. This gait abnormality is mistakingly called "shoulder lameness," but in fact is caused by pain in the back half of the foot.
Horses with stringhalt demonstrate a very specific gait characterized by exaggerated hock flexion varying from stiffness, which is only seen during periods of excitement, to a marked flexion in which the foot of the affected leg strikes the abdomen. Horses sometimes are almost unable to move forward without "bunny-hopping." They also have difficulty in stepping backward or circling. 1,4
Several gait abnormalities are caused by nerve damage. One of the most commonly affected nerve is suprascapulare nerve, which emerges from the chest underneath the shoulder and supplies the muscles of the shoulder. Injury results in wasting of the muscles on the outside of the shoulderblade because of damage to their nerve supply. The condition is called "sweeny," or "shoulder slip."5