Systemic lupus erythematosus commonly known as SLE is a rare autoimmune mediated disease which is seen in dogs. SLE has a variety of signs of most often cases are presented because of lameness or skin disorders.
What is the Cause?
The primary cause of SLE is unknown in dogs and humans, although several factors have been suggested. Here are some of the factors:
- Genetic inheritance
- Exposure to environmental factors like ultraviolet light, which definitely induces a photosensitivity reaction in affected animals
- Exposure to viral infections
- Endocrine factors
- Drug administration like anticonvulsants, contraceptives, hydralazine, isoniazid, penicillamine, procainamide and vaccinations
- Suppressor T cell deficiency and other immunological disorders
What the primary cause the disease is characterized by the production of non-specific antibodies (antinuclear antibodies - ANAs) by the animal which may attack specific cells or tissues like
- Red blood cells - Erythrocytes
- White blood cells - Leukocytes
These ANAs combine with free DNA to form DNA-antiDNA complex and can become deposited in a variety of tissues causing a Type III hypersensitivity reaction, including:
- The synovial membrane
- The walls of arterioles causing necrosis and fibrosis
- The glomeruli resulting in glomerulonephritis
*Note both dogs and humans with SLE have low concentrations of thymic factors in their blood.
Breeds that SLE typically occur in:
- Afghan Hounds
- German Shepherd Dogs
- Irish Setters
- Old English Sheepdogs
- Rough Collies
- Shetlabd Sheepdogs
SLE usually occurs in middle-aged dogs around age 6, but there is no age or sex predilection in dogs.
Signs to watch for:
- Anaemia due to haemolysis of red blood cells
- Coagulopathy due to thrombocytopenia
- Recurrent shifting lameness associated with a polyarthritis (seen in 75% of cases)
- Recurrent shifting lameness associated with a pilynyositis
- Myocarditis and pericarditis
- Neutological signs including seizures, psychoses and polyneuropathies
- Oral ulcers
- Pneumonitis or pleuritis
- Polydispsia and pilyuria with proteinuria due to glomerulonephritis
- Skin lesions including alopecia, cellulitis, crusting, erythema, furunculosis, panniculitis, seborrhoea, ulcers (mucocutaneous junctions and footpads), scar formation (50% of cases) The lesions can affect the face, ears, limbs, and body
Multiple organ system involvement makes diagnosis complicated.
What is the Diagnosis?
Dogs should have at least 2 manifestations of the disease and diagnosis is made by indentification Of ANAs by an indirect immunoflurescent test, and by histolathological examination of skin biopsies for lymphohistiocytic interface dermatitis, thickened basement membrane, vasculitis, subepidermal vesicles, basal cell degeneration
Anaemia may be present and a direct Coombs' test may or may not be positive. Other haematological changes may include, thronboctopaenia, leucopaenia or leucocytosis, proteinuria and hypergammaglobulinaemia.
Unfortunately the ANA test can give a false positive result in 20% of dogs with infectious diseases like leishmaniasis. The Lupus Erythematosus (LE) test is not as useful as it lacks soecificity and sensitivity and can vary daily.
What is the treatment?
- Coticosteriods - prednisone, prenisolone, methylprednisolone
- Other immunomodulating drugs like azathioprine, cyclophosphamide chlorambucil, sometimes in combination with corticosteroids.
- Levamisole has been beneficial in some cases 2.5mg every 48 hours
- Aspirin has been beneficial in some cases
- Vincristine has been used if thrombocytopenia is severe
- Management of secondary disease like renal failure
What is the prognosis of this condition?
Unfortunely, the prognosis is unpredictable to poor and it is worse if coagulopathy or haemolytic anaemia are present. It is reported that over 40% of cases die in the first 12 months following the diagnosis, but long term remission does occur in some dogs. I knew of a Chinese crested that had this and the first year was terrible. She was 4 years old and had thousands of dollars worth of treatment, but after a year she's stable with the help of medications and is 10 years old now.
What are the Long term issues?
Unfortuntely, euthanasia is often requested in animals that are refractory to treatment.