Discoid Lupus Erythematosus
What is discoid lupus?
Discoid Lupus Erythematosus (DLE) is a skin condition of dogs. It typically causes a loss of color in the hairless, moist part of the nose. A normally black nose may fade to gray or pink. The discoloration can be accompanied by ulcers and bleeding. The skin around the nose may also look abnormal, and rarely, the disease affects other parts of the skin. It does not affect other organs.
What causes discoid lupus?
The skin lesions in DLE are thought to arise when the animal’s immune system mistakenly targets the skin. The immune system normally clears infections and any substances that are “foreign” to the body, while ignoring, or tolerating, substances that are normally found there. We believe that in DLE, the immune system considers some of the normal components of the skin as foreign. It uses the mechanisms normally launched at foreign invaders to try to “clear” these skin components. The resulting inflammation and skin damage lead to the visible changes seen on the surface.
Unfortunately, we do not know all the factors that contribute to this disease. We do know that some breeds of dogs seem more prone to developing the disease. In many dogs, sunlight exacerbates or triggers the disease. Once DLE has developed, it tends to be a lifelong condition due to the long lasting “memory” of the immune system.
How is discoid lupus diagnosed?
The diagnosis is based on skin biopsies. Due to the location of the skin lesions, general anesthesia or sedation may be required to collect the biopsies.
How is discoid lupus treated?
Treatment consists of oral medications, topical therapy, or a combination of both. Oral medications are usually prescribed, as dogs tend to resist the application of medications to the nose, and can also quite easily remove them. Since DLE can be exacerbated by sun exposure, a sunscreen (not containing zinc oxide) should be applied to the nose when the dog goes outside. It is best to keep your dog indoors during the peak daylight hours.
The treatment for DLE may need to be continued for life, but serious side effects from the treatments are uncommon. Routine rechecks are recommended to enable the dose of medications to be kept as low as possible.