Horse Bone Diseases

The skeletal structure of a horse consists of myriad bones all working together to support its body mass. When the joints and muscles activate the movement of these bones, the result is the subsequent locomotion of the horse. Therefore, when a horse suffers from a bone disease, the animal will not only experience physical discomfort but will often lose its ability to move or, in the worst-case scenario, will become completely immobilized.

  1. Spavin

    • A degenerative arthritis of the lower joints of the hocks, spavin initially appears as a hard, bony swelling at the front, inside and lower edges of a horse’s hock, and is often the result of a strain, sprain or trauma that caused the bone’s surface to become inflamed. The inflammation then leads to the development of an “exostosis” (new growth) that encroaches on the surface of the joint and produces the arthritis. Symptoms include the formation of a hard, bony swelling and chronic lameness that is increased when the horse’s hock is flexed for thirty seconds to a minute.

    Ringbone

    • Ringbone affects a horse’s pastern and coffin joints. Although it may occur at any age, ringbone is most often seen in older horses. Several factors predispose an animal to ringbone, including conformation defects, heredity, improper foot balance and incorrect shoeing. However, it may be caused by direct trauma to the pastern or coffin joint or by concussion from regularly traveling on hard surfaces. Symptoms include lameness and usually, but not always, a bony swelling in the affected area.

    Navicular Disease

    • Navicular disease is a degenerative process involving the deep flexor tendon and the small bone (navicular bone) that lies at the back of a horse’s foot. The navicular bone degenerates, usually on the rear surface, creating hollows and cavities (lacunae) and producing chronic pain. Although the disease most often occurs in older animals, it can occur in horses of any age, especially if they have been used for extended periods of roadwork or jumping. Symptoms include “pointing” or standing with one foot ahead of the other, lameness in the forelegs, and stumbling. The horse will also walk toes first in an attempt to avoid putting weight on its heels.

    Founder

    • Founder usually affects a horse’s forefeet and involves inflammation of the laminae. Since the wall of the heel and sole is extremely firm, there is no room for swelling, and because the laminae are highly sensitive, the animal experiences acute pain. There are several causes of founder, including a horse’s consumption of too much grass while getting too little exercise; overindulging on grain or corn; retaining afterbirth; and standing for excessively long periods without being able to lie down or move around. Symptoms include marked lameness, elevated body temperature, increased pulse rate, heat in the coronet, difficulty lying down or getting up, and obvious pain when the foot is touched.

    Splints

    • Located at the back and to each side of a horse’s cannon bone, the splint bones are attached to the covering of the cannon bone by a ligament. If the horse’s forelegs are subjected to excess stress or strain, the ligament can become stretched and the covering will detach from the bone. Subsequent inflammation leads to swelling, and symptoms include localized pain and noticeable lameness. However, the pain and lameness normally abate in two to three weeks, but the swelling gradually becomes harder as inflamed fluid and tissue calcify and fuse the splint bone directly to the cannon bone.