Chronic progressive lymphedema (CPL) is a disease of some breeds of

draft horse A draft horse (US), draught horse (UK) or dray horse (from the Old English ''dragan'' meaning "to draw or haul"; compare Dutch ''dragen'' and German ''tragen'' meaning "to carry" and Danish ''drage'' meaning "to draw" or "to fare"), less often ...

, whereby the lower legs becomes progressively more swollen. There is no cure; the aim of treatment is to manage the signs and slow progression of the disease. The cause of CPL is not known, although it is suspected that a genetic disorder of

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

metabolism prevents the lymphatic vessels from functioning properly, leading to

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...

of the lower limbs. CPL resembles the human disease elephantiasis verrucosa nostra.

Signs

CPL is a progressive disease, which begins below the fetlock and gradually moves up the leg. All legs are affected, the hindlimbs usually more seriously so. Initial signs include thickening, crusting and folding of the skin. These early signs may be hidden by the long hair (

feather Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...

) on the horse's lower legs. Affected areas are itchy, causing the horse to stamp its feet and rub its legs, and painful, so that the horse may be reluctant to allow its legs to be touched. As CPL progresses, ulcers develop on the pasterns, and fibrosis leads to hardening of the skin and the development of nodules which may become baseball sized. Secondary

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

s with microbes or mites commonly cause complications. Infestations with the mange mite '' Chorioptes equi'' are very itchy, and lead to self-trauma and dermatitis. The quality of the hoof is often poor; hooves are prone to cracks, splits and the development of thrush and abscesses; horses may develop

laminitis Laminitis is a disease that affects the feet of ungulates and is found mostly in horses and cattle. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, and increased temperature in the hooves. Sever ...

. Chestnuts and ergots are often misshapen and irregular.

Management

There is no cure for CPL; the aim of treatment is to relieve the signs of the disease, and to slow the progression. Management requires daily care to prevent infection of the affected skin. The first step is to trim the feather from the lower leg, to ensure no affected areas are missed, and to allow application of treatments directly to the affected skin. Bacterial infections can be treated by gentle washing and drying of the skin. Topical treatments are required to treat chorioptic

mange Mange is a type of skin disease caused by parasitic mites. Because various species of mites also infect plants, birds and reptiles, the term "mange", or colloquially "the mange", suggesting poor condition of the skin and fur due to the infection ...

(caused by the mite '' Chorioptes equi''), as the mites are not vulnerable to oral or systemic treatments when they are within the crusts on the skin. Daily exercise assists with the flow of lymph. Combined decongestive therapy involves massage of the leg to move the lymph, followed by specialized compression bandaging which creates a pressure gradient up the leg. Horses with CPL often have poor-quality hoof, so regular trimming is required to help keep the hoof healthy.

Epidemiology

Affected breeds include the

Shire Shire is a traditional term for an administrative division of land in Great Britain and some other English-speaking countries such as Australia and New Zealand. It is generally synonymous with county. It was first used in Wessex from the beginn ...

Clydesdale Clydesdale is an archaic name for Lanarkshire, a traditional county in Scotland. The name may also refer to: Sports * Clydesdale F.C., a former football club in Glasgow * Clydesdale RFC, Glasgow, a former rugby union club * Clydesdale RFC, South ...

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...

, Gypsy cob, and Friesian. Signs are usually only seen in horses older than two years. Both sexes are affected.

References

{{Reflist Horse diseases