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Discoid (Cutaneous) Lupus Erythematosus

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What is discoid lupus erythematosus?

Discoid lupus erythematosus (DLE), also known as cutaneous lupus erythematosus, is an autoimmune disease that affects the skin. DLE is the most common type of cutaneous (skin) lupus in dogs; it is very rare in cats. Dogs with DLE develop crusting and scabbing of the skin, usually starting around the nose, and they lose skin pigmentation in the affected area.

What causes DLE?

Discoid lupus erythematosus is an autoimmune disease in which the body’s own immune system is activated to attack the body. This immune attack kills a layer of cells within the skin, causing the surface of the skin to slough (shed).

The underlying cause of DLE is unknown. It has been noted that ultraviolet (UV) light appears to worsen DLE and the condition is more common in sunny climates. Inflammation triggered by UV radiation is thought to contribute to this condition. A genetic basis for the condition hasn’t been established yet, although DLE has been diagnosed in siblings within a litter and in mother-daughter pairs.

What are the signs of DLE?

Dogs with DLE typically develop erosions, ulcers, and de-pigmented areas (light discoloration of the skin) around the nose. In many patients, the nasal planum (the hairless area around the nostrils) becomes smooth, losing its bumpy, cobblestone-like texture. The skin around the nose also has a well-developed blood supply, so if skin lesions occur near a major blood vessel, heavy bleeding can result.

"Dogs with DLE typically develop erosions, ulcers, and de-pigmented areas 
(light discoloration of the skin) around the nose."

In some dogs, the lesions spread to other areas of the body. These lesions most commonly affect the skin around the eyes, around the lips, on the ear flaps (pinnae), and around the genitals (rarely). Skin lesions can also become generalized, spreading across the entire body, although this is uncommon.

How is DLE diagnosed?

The diagnosis of DLE requires a skin biopsy. Your veterinarian will obtain a small sample from a skin lesion by doing a punch biopsy, in which a circular blade removes a small, circular plug of skin. Your dog will likely require general anesthesia or heavy sedation for this procedure, because the skin on the face and muzzle is very sensitive.

© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Jun 13, 2025.