Lupus erythematosus (systemic, cutaneous/discoid)
There are several forms of lupus erythematosus that are recognized in people, two of which have been identified in dogs. Lupus is an autoimmune disorder, meaning that the body mounts an inappropriate immune response to some part of itself.
Systemic lupus erythematosus (SLE) is an uncommon but severe disorder in which the inappropriate immune response is widespread in the body, and can cause arthritis, kidney disease, anemia, and skin disease. Cutaneous lupus erythematosus (CLE) is thought to be a milder variant of SLE, and the problems are confined to the skin. CLE is also called discoid lupus erythematosus
unknown, but the condition runs in families.
SLE most commonly affects joints, muscle, skin, blood, and/or kidneys. The condition tends to wax and wane, so your dog will have periods of remission and of flare-up. The kinds of problems you may notice include shifting lameness (ie varies depending on which joint is affected at any time), weakness and pale gums (due to anemia), and/or increased drinking and urination (kidney disease). The face and the feet are the areas of the skin most often affected, with ulcers and loss of pigment on the nose, and ulceration and thickening of the footpads.
With CLE, you are most likely to see red, scaling areas of inflammation on your dog's face, and loss of pigment from the nose. There may also be lesions on the ears and thickening of the footpads. Affected dogs are otherwise healthy.
Nasal scarring is common with both SLE and CLE. Exposure to ultraviolet light is a factor (especially in CLE), and so the condition is seen more often and is more severe in the summer and in sunny parts of the world.
Because SLE can affect many different body systems, diagnosis is challenging. (In fact it is sometimes called, "the great imitator"). Once suspected, diagnosis is confirmed by specific blood tests and biopsy for examination by a veterinary pathologist.
CLE is diagnosed through examination of biopsy samples.
Treatment for SLE generally requires relatively high doses of steroids in combination with chemotherapy. In general, dogs with joint, muscle, or skin disease seem to respond better to medication, and have longer periods of remission, than those with severe blood or kidney problems. Unfortunately, many dogs with SLE die or are euthanized within a year of diagnosis, either due to the disease itself, the inability to control it, and/or unacceptable drug reactions. In other dogs, the disease can be well-controlled with medication for several years.
CLE is treated with relatively lower doses of steroids plus vitamin E and fatty acid supplements. Treatment generally needs to be lifelong, and dogs usually do well on it.
Exposure to ultraviolet radiation worsens the skin lesions in both conditions, so sunscreen is adviseable and dogs should be sheltered from peak sunlight (approximately 10:00 to 3:00).
For the veterinarian: Treatment for SLE must be individualized for each dog, generally starting with large doses of systemic glucocorticoids, and going to other immunomodulating or chemotherapeutic drugs if necessary. There is a good discussion of treatments for both forms of lupus erythematosus in the reference below.
The list of rule-outs with SLE is extensive, due to the varied and changeable cutaneous and systemic manifestations of this disorder. Diagnosis is based on signs of multisystem involvement (most commonly anemia, thrombocytopenia, glomerulonephritis, polyarthritis, nasal and footpad dermatitis, fever of undetermined origin), a positive antinuclear antibody test, and histopathologic and immunopathologic evaluation.
Diagnosis of CLE is by histopathologic and immunopathologic evaluation.
Although the mode of inheritance is not known for either cutaneous or systemic lupus erythematosus, these conditions run in families. Affected animals should not be bred and it is prudent to avoid breeding their close relatives as well.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Scott, D.W., Miller, W.H., Griffin, C.E. 1995. Immunologic Skin Diseases. In Muller and Kirk's Small Animal Dermatology. p. 578-588. W.B. Saunders Co., Toronto.