Known as collie nose, discoid lupus erythematosus (DLE) is an inflammatory skin disease seen in dogs and, very rarely, in cats. It usually affects the face and nose. It’s possible that DLE is a non-systemic type of systemic lupus erythematosus (SLE), but it isn’t as serious as SLE.
Owners usually first notice a loss of pigmentation around the dog’s nose. In some dogs, the bridge of the nose, the lips, the skin around the eyes, the ears, and the genitals may also be affected. DLE can change the surface of the nose from its normal cobblestone texture to smooth. Ulcerated sores may eventually occur. Some dogs find the disease really irritating and annoying, while others don’t seem to notice it much.
There is some thought that DLE could be a seasonal disease, because it’s affected by the ultraviolet rays in sunlight and is usually more of a problem in summer. It’s seen more often in high altitude locations where exposure to ultraviolet light is increased.
It’s most often seen in Brittanys, Collies, Shetland sheepdogs, German shepherds, German shorthaired pointers, and Siberian huskies. Females are at slightly more risk than are males. Dogs with DLE are often predisposed to squamous cell carcinoma.
Diagnosis can be confusing, as the same signs can be seen in such conditions as solar dermatitis, pemphigus, and ringworm. In addition, the antinuclear antibody (ANA) tests that are positive in SLE are usually negative in DLE.
Oftentimes the only treatment needed is to keep the dog out of a lot of sunlight, or at least out of sunlight during the middle of the day. Sunscreens without zinc oxide can help. Of course, dogs may want to lick the sunscreen off, so keep an eye on the dog when you use it. Use sunscreen made for dogs, because the sunscreens made for people contain ingredients (particularly zinc oxide) that are poisonous if ingested. Topical corticosteroids can be used if needed. Severe cases may require the use of oral corticosteroids, such as prednisolone, or immunosuppressive medications such as azathioprine. Oral vitamin E and omega-3 and omega-6 fatty acids can help, but several months of treatment are needed with those supplements before any effect can be seen.
Like SLE, treatment is life long, although DLE can have a long remission time during which sores don’t occur. Unlike SLE, DLE is not potentially fatal.