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

draft horse A draft horse (US) or draught horse (UK), also known as dray horse, carthorse, work horse or heavy horse, is a large horse bred to be a working animal hauling freight and doing heavy agricultural tasks such as plowing. There are a number o ...

, 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 encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...

metabolism prevents the lymphatic vessels from functioning properly, leading to

edema Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. S ...

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 an exa ...

) 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 tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

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 of the feet of ungulates, found mostly in horses and cattle involving inflammation of the laminae. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, and increased temperatur ...

. 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 infecti ...

(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. It is generally synonymous with county (such as Cheshire and Worcestershire). British counties are among the oldes ...

, Clydesdale, Belgian,

Gypsy cob The Gypsy Cob, also known as the Traditional Gypsy Cob, Irish Cob, Romani Cob, Gypsy Horse, or Gypsy Vanner, is a breed of domestic horse from the British Isles. It is a small, solidly-built horse of cob conformation and is usually piebald. It ...

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

References

{{Reflist Horse diseases