Understanding Of Navicular Disease In Horses

By Enid Hinton


Sometimes problems develop on the navicular bone and the surrounding tissues. This is a bone found on the front side of the foot. It is also behind the coffin bone and next to small pastern bone. Strong tendons are bundled in this area running up to the end of the coffin bone. They also run across the soft tissues. Cartilage separates navicular bone and the coffin bone. For further protection, there is a small fluid sac over the navicular bone to prevent cases of abrasion. The syndrome affects this area causing inflammation and bone degeneration that can cause disabling lameness in horses. It is prudent that navicular disease in horses need to be given the necessary attention.

There is no known single cause of this syndrome. However, there are two theories put forward to explain what could be the cause. First, it is believed that compressing of navicular under the tendons and the small pastern bones, as explained above, can cause degeneration of cartilage. This causes the cartilage to flatten and results to it becoming less springy and is unable to absorb bigger shock.Researchers have also found gradual cartilage erosion and degeneration along the surface next to this bone where there was suspected compression. This is associated with biochemical changes and has similarity to human osteoarthritis. This erosion may progress to a point that the underneath bone becomes exposed and thus not protected.

What follows is constant rubbing of the tendon against this bone surface causing inflammation. In addition, Compression causes an increase in bone density under the cartilage especially near the tendons. Increase in bone density makes the bone brittle and may actually lead to a breakage.

Tension on the ligaments in this area also causes the problem. It causes strain on ligaments pulling the bone together leading to degeneration. This also decreases the blood flow to and from the bone. This region is full of blood vessels. When they are pulled apart, the vessels permanently thicken and restrict blood flow.

Restricted blood flow to and from this bone causes a buildup on the particular bone. In response to increased pressure and less blood supply, this bone absorbs mineral from its center. Tension on the other hand, causes a condition called exostoses. The ligaments attach to the bone giving it a canoe shape and they may tear in extreme cases.

The veterinary doctor recommends treatment dependent on the extent of this syndrome. The medication can range from conservative methods to more aggressive ones. Such interventions include shoeing for therapeutic purposes, oral and intravenous medication and surgery. Since the response to treatment is not always guaranteed, it is advisable to start with conservative methods before trying more aggressive ones.

Since response to any intervention is not guaranteed to be positive, most vets start with conservative methods and try aggressive ones when they do not work. A metallic bar is placed across the heel in shoe treatment. This is meant to relieve pressure and improve blood flow in the region.

The use of medication involves injection with vasodilators to improve blood flow. There are also anti-inflammatory drugs to treat pain. There are also oral medications aimed at relieving the problem. Surgery involves severing the nerves that could be causing the pain but causes the horse to lose sensation in the back of a foot.




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