CHRONIC PROGRESSIVE LYMPHEDEMA (CPL) IN DRAFT HORSES
A condition characterized by progressive swelling, hyperkeratosis and fibrosis of distal limbs has been characterized in Shires, Clydesdales and Belgian Draft horses and unfortunately affects numerous horses within these breeds. The disease has also been recognized in Gipsy Vanners; however, only a few horses have been evaluated at this point of time. This chronic progressive disease starts at an early age, progresses throughout the life of the horse and often ends in disfigurement and disability of the legs, which inevitably leads to the horse's premature death. The pathologic changes and clinical signs closely resemble a condition known in humans as chronic lymphedema or elephantiasis nostras verrucosa. The condition has therefore been referred to as chronic progressive lymphedema (CPL). The lower leg swelling is caused by abnormal functioning of the lymphatic system in the skin, which results in chronic lymphedema (swelling), fibrosis, decreased perfusion, a compromised immune system and subsequent secondary infections of the skin.
The clinical signs of this disease are highly variable. It is often first addressed as a marked and “therapy-resistant” pastern dermatitis (scratches). The earliest lesions, however, are characterized by skin thickening, slight crusting and possible skin folds in the pastern area. While readily palpable, these early lesions are often not appreciated visually as the heavy feathering in these breeds covers these areas. Upon clipping of the lower legs, it becomes obvious that the lesions are far more extensive than expected. Secondary infections develop very easily in these horse's legs and usually consist of chorioptic mange and/or bacterial infections. Pigmented and non-pigmented skin of the lower legs are affected. Appropriate treatment of the infections (pastern dermatitis) is not successful as underlying poor perfusion, lymphedema and hyperkeratosis in association with the heavy feathering present perfect conditions for repetitive infections with both chorioptic mange as well as bacterial infections. Recurrent infections and inflammation will enhance the lymphedema and hence, the condition becomes more chronic. As a result, the lower leg enlargement becomes permanent and the swelling firm on palpation. More thick skin folds and large, poorly defined, firm nodules develop. The nodules may become quite large and often are described as "golf ball" or even "baseball" in size. Both skin folds and nodules first develop in the back of the pastern area. With progression, they may extend and encircle the entire lower leg. The nodules become a mechanical problem because they interfere with free movement and frequently are injured during exercise. This disease often progresses to include massive secondary infections that produce copious amounts of foul-smelling exudates, generalized illness, debilitation and even death.
To MANAGE chronic progressive lymphedema (CPL)
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