Systemic Lupus Erythematosus

Also known as: SLE — Multi-Systemic Immune Mediated Disease

Introduction

Systemic Lupus Erythematous is an immune-mediated disease which can affect many different organ systems. The immune system is directed against various tissues of the body and immune complexes cause a type III hypersensitivity reaction. The condition is documented in cats and dogs but the etiology is not known. The disease has been reported in colonies of dogs suggesting that there may be a genetic or infectious component to the cause.

Diagnosis

Clinical Signs

Clinical signs depend on the tissues and organ systems affected by the condition. A combination of the following signs may be seen:

• Immune-mediated haemolytic anaemia
• Immune-mediated thrombocytopenia
• Polyarthritis
• Glomerulonephritis
• Vasculitis
• Dermatitis
• Seizures

Diagnosis of SLE is made on a combination of clinical findings, haemotologic, serum biochemistry and immunological testing results. Diagnosis can be challenging as the condition can mimic a number of other diseases. Ruling out differential diagnoses will help in securing a definitive diagnosis.

Laboratory Tests

A positive antinuclear antibody (ANA) test is supportive of a diagnosis of SLE.

Treatment

Treatment is with immunosuppressive drugs. Corticosteroids are the most widely used immunosuppresive drugs, prednisolone or dexamethasone is used alone or in combination with azathioprine or cyclophosphamide in more severe cases. Typically the dose can be tapered once the condition is under control.

Prognosis

Prognosis is good with appropriate treatment.

Literature Search

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Systemic Lupus Erythematosus publications

References

• Blood, D.C. and Studdert, V. P. (1999) Saunders Comprehensive Veterinary Dictionary (2nd Edition) Elsevier Science
• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier

From Pathology

• Systemic (SLE)
  • Multiple organs involved
  • Cats, dogs, horses
  • Immune dysregulation:
    • Damaged T-cell suppressor function, either primary deficiency or antibody mediated
    • Cytokine dysregulation
    • Resulting B-cell hyperactivity -> antibodies to self antigens -> antigen-antibody complexes deposited in various tissues -> Type III hypersensitivity
  • Lesions localised or generalised
  • Erythema, alopecia, depigmentation, crusting and scaling, ulceration
  • Microscopically: lymphohistiocytic interface dermatitis, thickened basement membrane, vasculitis, subepidermal vesicles, basal cell degeneration

• Also see Discoid Lupus Erythematosus