Chronic progressive lymphedema is a serious and difficult disease in draft horses, and is characterized by progressive swelling, increased thickness of the skin called hyperkeratosis and scarring of the distal limbs. The veterinary staff at UC Davis indicates the disease starts at an early age and progresses throughout the horse's life, which eventually leads to disfigurement and premature death. The disease and clinical symptoms are similar to a disease in humans called elephantiasis.
The lower leg swelling is caused by abnormal functioning of the lymphatic system, which results in chronic swelling, scarring, decreased immunity and chronic infections of the skin. The disease starts out as small skin infections on the lower legs that are not uncommon, called scratches, and after clipping the long feathers many times the infection is much more severe than expected and large areas of the skin are thickened with crusts. Also, many of these horses have a mite called Chorioptes that further increases the inflammation and infection. As the crusts and skin folds enlarge, large nodules can develop that cause mechanical difficulty in walking, and the infections continue to increase as they are usually resistant to antibiotics.
Unfortunately, there is no cure for the condition and managing the condition is the most that can be expected. Treatment includes clipping the feathers off of the legs to allow for topical medication. Since the horses have large nodules and scarring on the lower legs, the blood supply is decreased, which makes it difficult to treat the skin infections. If you have a draft horse with this syndrome, ask your veterinarian about treatment options.
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