section name header

Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • CPL is a disorder characterized by lymphedema of the lower extremities, leading to recurrent infections and severe fibrosis
  • Affected organ systems are hemic/lymphatic/immune and skin/exocrine. Exact pathogenesis is unknown
  • Elastin within the skin and around lymphatic vessels of the skin and subcutis is altered with increased levels of circulating anti-elastin antibodies
  • Ineffective lower extremity lymph drainage leads to lymph stasis, which induces diffuse nodular fibrosis and ischemia of the skin and subcutaneous tissues
  • Heavy feathering and decreased skin barrier function due to LE and ischemia foster recurrent bacterial and parasitic dermatitis

Signalment !!navigator!!

  • Draft horses with heavy feathering are affected—Shires, Clydesdales, Belgian draft horses, Friesians, Gypsy Vanners, some German draft breeds, and English Cobbs. Certain familial lines of draft horse breeds are more affected
  • The high incidence of CPL in certain breeds suggests a genetic component. Evaluation of FOXC2 (LE–distichiasis syndrome) and ATP2A2 (Darier–White disease) genes revealed no association with CPL. Other candidate genes are ubiquitin protein ligase E3A, CD109, transforming growth factor-β and myotubularin-related protein 6

Signs!!navigator!!

  • Develops as early as 2–4 years of age and progresses throughout life
  • Often more pronounced in the hind legs
  • Starts in the fetlock and pastern and expands proximally
  • Mild and/or early CPL—often not diagnosed under heavy feathering
    • After clipping mild pitting edema is appreciated resulting in lack of distinction of tendons and metatarsus/metacarpus and fetlock
    • There is mild rippling of skin surface of pastern and fetlock
    • Scaling
    • Chorioptes infestation results in pruritus and stomping
    • Oozing and crusting due to secondary infections
  • Severe/chronic CPL—lesions progress to carpus and tarsus
    • Leg swelling is firm from fibrosis of the CPL
    • Numerous firm folds and nodules can be palpated
    • Skin surface is extremely scaly, moist, and often greasy
    • Erosions and ulcers occur due to self-trauma (pruritus and interference of movement)
    • Persistent infections affect deeper tissues and induce lymphangitis and swelling of the entire leg
    • Coronary band is markedly hyperkeratotic and hyperplastic
    • Hoof quality is poor; may be brittle and chipped with splits and cracks
    • Repeated bouts of thrush and deep hoof abscesses are common
    • Chestnuts and ergots tend to be misshapen and hyperkeratotic

Causes and Risk Factors!!navigator!!

  • Heavy long feathering in association with wet and muddy environment
  • Lack of movement increases the LE

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Clinical presentation and history are characteristic. Thorough palpation of lower legs is necessary to identify early pitting edema.

Differential Diagnosis!!navigator!!

Pastern dermatitis in draft horses, in particular if several legs are affected, raises the concern for CPL.

CBC/Biochemistry/Urinalysis!!navigator!!

N/A

Other Laboratory Tests!!navigator!!

Skin scrapings and bacterial culture assist in identification of chorioptic mites or secondary pyoderma, respectively.

Imaging!!navigator!!

Lymphangiography illustrates dilated, tortuous lymphatic vessels in the distal legs and confirms the diagnosis.

Other Diagnostic Procedures!!navigator!!

N/A

Treatment ⬆ ⬇

Outline

TREATMENT

  • No curative treatment exists. Early recognition and careful management can drastically improve the condition and slow progression of the disease
  • Clipping of feathers is imperative for successful long-term management
  • Legs need to be kept clean and dry

!!navigator!!

Activity

  • Exercise increases circulation, lymph drainage, and lymph flow. Light exercise can be performed with the horse wearing compression bandages that constitute part of combined decongestive therapy
  • Cold water rinses are recommended on limbs with clipped feathers after exercise. Skin needs to be dried after rinsing
  • Routine hoof care is important to avoid thrush
  • Combined decongestive therapy—includes daily manual lymph drainage massage by a trained person and compression bandaging using specialized short-stretch bandages in phases 1 and 2. Horses can be walked with the bandages

Client Education

Owners must commit to life-long management.

Surgical Considerations!!navigator!!

Surgical debulking of nodules or epidermal shaving with subsequent compression bandaging has been suggested. However, intervention will disrupt the lymphatic vascular bed and enhance LE, unless stringent compression treatment is used.

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

Treatment of Chorioptes is crucial (fipronil or lime sulfur sprays; ivermectin; moxidectin). Bacterial infections need to be treated.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Possible Complications!!navigator!!

Permanent lameness and a poor quality of life.

Expected Course and Prognosis!!navigator!!

CPL can lead to premature euthanasia.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Age-Related Factors!!navigator!!

Progression with age.

Abbreviations!!navigator!!

  • CPL = chronic progressive lymphedema
  • LE = lymphedema

Suggested Reading ⬆ ⬇

Affolter VK. Chronic progressive lymphedema in draft horses. Vet Clin North Am Equine Pract 2013;29(3):589–605.

Author(s) ⬆ ⬇

Author: Verena K. Affolter

Consulting Editor: Gwendolen Lorch

Additional Further Reading ⬆

Click here for Additional Further Reading