Introduction
Lupus is an autoimmune disease which occurs rarely in dogs, although it probably is underdiagnosed. The signs of lupus vary widely and often are missed until the disease has reached an advanced stage. The exact cause of lupus is not known, but there is strong evidence that it is genetically inherited.
There currently are two forms of lupus that occur in dogs. The clinical signs associated with each form of the disorder are vastly different and may be influenced by genetic, environmental, pharmacologic and/or infections factors.
Symptoms of Lupus in Dogs
Systemic Lupus Erythematosus (SLE)
Systemic lupus erythematosus is a multi-system autoimmune disease characterized by the formation of antibodies against a number of normal body cells or tissue. Basically, the dog’s body attacks itself, from the inside out. The mean age of dogs with this disease is 6 years, but it can occur in dogs of any age. German shepherds are clearly overrepresented. Other breeds that seem predisposed to developing SLE include Shetland sheepdogs, Collies, Old English sheepdogs, Afghan hounds, Beagles, Irish setters and Poodles. Signs of SLE can occur anywhere, including in the musculoskeletal system, skin, kidneys, liver or other organ systems. The symptoms can occur suddenly or slowly and can wax and wane over time. Often, they follow a cyclic pattern.
Shifting-leg lameness is the most common sign of this disease, followed by lethargy, anorexia and skin lesions (especially in areas exposed to sunlight). An owner may notice her dog limping on a front leg, then not limping at all. Weeks or months later, the same dog might start limping on a back leg, or on the other front leg. This sporadic lameness is attributable to swollen, painful joints. Other signs can include periodic fever, oral ulcers, arthritis, pale gums, hair loss, increased thirst, increased urination and a number of neurologic abnormalities.
Diagnosis of SLE cannot be made based on any single test. The veterinarian must consider a constellation of clinical signs and exclude other possible underlying causes of those signs (cancer, infection, etc).
Discoid Lupus Erythematosus (DLE)
Discoid lupus erythematosus is considered to be a relatively benign variant of SLE that primarily affects the skin – especially on the face. The most commonly affected site is the hairless surface of the nose, called the “nasal planum.” Other possible sites are the lips, mouth, periocular area (around the eyes), pinnae (ears) and, rarely, the genitalia and lower limbs. DLE, sometimes referred to as “collie nose” or “nasal solar dermatitis,” is one of the most common immune-mediated skin diseases in dogs. Some breeds are predisposed, including Collies, German shepherds, Siberian huskies, Shetland sheepdogs, Alaskan malamutes, Chow chows and crosses of these breeds. There is no age or sex predilection. Dogs with DLE are otherwise healthy.
Clinical signs of DLE usually begin with depigmentation of the skin on the nose, which becomes pale. The hairless surface of the nose changes from the normal rough or “pebbly” texture to a smooth, shiny surface. There may be flaking and crusting at junctions between haired and hairless areas of affected skin. Depigmentation progresses to skin erosions and ulcers, with accompanying tissue loss and scarring. Pain and pruritis (itchiness) may or not be present. Exposure to sunlight tends to exacerbate the effects of DLE, which occurs more commonly in summer months and sunny climates.
If you notice these signs in your dog, please make an appointment with your veterinarian as soon as possible. Lupus cannot be cured, but with early diagnosis the effects of lupus can be managed.