The first thing we need to establish is that this is a soundness problem in horses, and not actually a disease. Veterinarians prefer to call it a syndrome. To better understand it, you really need to have some knowledge of the horse’s forelimb anatomy. The navicular bone lies behind the coffin bone and under the pastern bone.
It is supported by ligaments above, below and on the side. Cartilage lies between the navicular bone and coffin joint and between the navicular bone and the DDF tendon. The bursa is a small sac filled with a lubricative substance that protects the DDF tendon and navicular bone from abrasion as the tendon slides over the area. The bursa is located between the navicular bone and DDF tendon.
Causes of Navicular
There are several known theories to the cause of Naviular. Two important factors are:
- Compression of the navicular bone under the DDF tendon and the back of the small pastern bone. This compression can cause cartilage degeneration. With this cartilage erosion, the bone underneath becomes exposed, and the bursa and DDF tendon may become damaged by he constant rubbing against the navicular bone.
- Excessive tension placed on the ligaments that support the navicular bone, which results in strain and inflammation. This inflammation can decrease blood flow to and from the navicular bone, and cause a build up of pressure within the navicular bone. In response to the increased pressure and decreased blood supply, the navicular bone would absorb mineral from its center.
There are some factors that contribute to the cause of navicular such as conformation, body weight and horses that are stall-kept or have strong physical demands placed on them.
Symptoms of Navicular
The symptoms of Navicular are usually a gradual and progressive increase in lameness of the front legs. A tip-toe gait or walk is a common sign, as the horse is trying to walk on the toes due to the heel pain. They may also take longer to stop the stride because they will not place weight on the heel. Some other signs to look for include
- A continual shifting of body weight when standing
- A stumbling gait
- Shortening of the stride
- General irritability
After several months of pain, the feet may begin to change shape, becoming more upright and narrow.
Treatment of Navicular
Since there are different causes for Navicular in horses, no single treatment works for all cases. The advanced degenerative changes are non-reversible, so the best thing do is manage the condition and focus on alleviating the pain.
- Shoeing is the most important long-term management plan for a horse with Navicular.
- Decreasing intense work
- Drugs to treat the pain or improve the blood flow into the vessels of hoof
- Surgery (Neurectomy) to sever the nerves, so the horse loses sensation in the back of the foot is an option that should be a last resort.
The prognosis for a horse with Navicular is usually guarded. After time, all horses with Navicular will need to lessen the strenuousness of their work, but with proper management, a horse with Naviular can remain useful for some time.
For further questions about Navicular, please contact us.
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