Lupus erythematosus is an immune-mediated disease in which the antigen-antibody complex lodges in the small vessels of many organs, including the skin. The exact stimulus for the antigen-antibody reaction is unknown. Two types of lupus occur in dogs.
Systemic Lupus Erythematosus
This is a complex disease affecting several body parts, including the skin, kidneys, heart, and joints. The first indication may be a stilted gait or lameness that wanders from joint to joint. Eventually, the lungs, nervous system, lymph nodes, and spleen may be involved.
Skin involvement is especially evident about the face and over the nose and muzzle, but may be found elsewhere. An erosive dermatitis, characterized by vesicles and pustules, develops in these areas, and is followed by crusting, oozing, and hair loss. The mucous membranes of the mouth are often involved. The foot pads can become thickened and ulcerated and may eventually shed. Anemia and bleeding problems may develop. Secondary pyoderma is a major cause of death.
The diagnosis is difficult, but is aided by a skin biopsy and an antinuclear antibody (ANA) test. This test is positive in 90 percent of cases.
Treatment: Treatment depends on what organs are involved. Most cases require chemotherapy. Secondary pyoderma must be treated aggressively. The outlook for long-term control is guarded.
Discoid Lupus Erythematosus
This is the second most common autoimmune skin disease, after pemphigus foliaceus. It is considered to be a milder form of systemic lupus and is limited to the face. Depigmentation of the nose is usually followed by the appearance of open sores and crusts. Collies, German Shepherds, Siberian Huskies, Shetland Sheepdogs, Brittanys, and German Shorthaired Pointers are most often affected. The typical appearance and location of discoid lupus, and the absence of other sites of skin involvement, make the diagnosis almost certain.
Treatment: Discoid lupus can be successfully managed with oral and/or topical corticosteroids. Oral vitamin E in a dose of 400 IU given every 12 hours, two hours before or after meals, is reported to be beneficial. Apply topical sunscreens during periods of exposure to sunlight (see Collie Nose). Sunblock may help as a preventative measure, as well. Ultraviolet injury severely aggravates this problem.