"Lupus" is a general term for an autoimmune disease characterized by the formation of antibodies against the body's own tissues. There are two distinct forms of lupus in dogs, each of which have different symptoms and consequences. They are discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE). DLE, sometimes referred to as "collie nose" or "nasal solar dermatitis," is one of the most common immune-mediated skin diseases in dogs and almost always is limited to the face, ears and mucous membranes. SLE is the more complex and serious of the two conditions and tends to target the skin, kidneys, liver, heart and joints.
Cause of Lupus in Dogs
The exact causes of lupus are not known, but it is thought that the disease has a strong genetic component. Other suspected contributing factors include viral infection, adverse drug reactions, stress and chronic exposure to ultraviolet radiation (sunlight). Sunlight exacerbates the effects of DLE, which occurs more commonly in summer months and sunny climates.
Prevention of Lupus in Dogs
There is no known way to prevent lupus in dogs. Affected animals should not be bred, because of the role that genetics play in this disease. Owners of dogs at increased risk of developing DLE should consider applying a high SPF, waterproof sunblock to their dogs' nasal planum (the fairly hairless area on the top of the nose/muzzle) and should keep them out of direct sunlight as much as possible.
Systemic lupus erythematosus is a very serious, progressive disease. Discoid lupus erythematosus is considered to be a much more benign, cutaneous (skin) variant of the systemic condition.
Lupus is an autoimmune disease which occurs rarely in dogs, although it probably is under-diagnosed. The symptoms of lupus vary widely and often are missed until the disease has reached an advanced stage. Two types of lupus occur in domestic dogs - discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE). The clinical signs associated with each form of the disease differ and may be influenced by genetic, pharmacologic, environmental and infectious factors.
Symptoms of Lupus in Dogs
Discoid (cutaneous) lupus erythematosus is a relatively benign variant of systemic lupus erythematosus that primarily affects facial skin. The most common site is the hairless surface of the bridge of the nose, called the nasal planum or planum nasale. Other sites are the lips, mouth, periocular area (around the eyes), pinnae (ear flaps) and, rarely, the genitalia or feet. Dogs with DLE usually are otherwise healthy. The symptoms of DLE can include one or more of the following:
Depigmentation (paleness) of the skin on the bridge of the nose
Skin redness (erythema), especially on the bridge of the nose, face and lips
Skin scaling and flaking, especially on the bridge of the nose, face and lips
Skin erosions (sores), especially on the bridge of the nose, face and lips
Skin ulcerations, especially on the bridge of the nose, face and lips
Skin crusting, especially on the bridge of the nose, face and lips
Scarring, especially on the bridge of the nose, face and lips
Pain at affected areas
Itchiness (pruritis), may or may not be present
Scratching at affected areas (variable)
Secondary bacterial infections (pyoderma)
In addition to losing its pigment, the hairless surface of the nasal planum in dogs with DLE typically transitions from its normal "pebbly" texture to a smoother, more shiny surface. Flaking and crusting at junctions between haired and hairless facial areas are also commonly seen. Many cases of DLE eventually go into remission.
Systemic lupus erythematosus is a much more serious condition than its cutaneous counterpart. SLE is a multi-system, immune-mediated disease characterized by the formation of antibodies against normal body cells and tissues. Basically, the dog's body attacks itself, from the inside out. While a large number of autoimmune symptoms can be caused by SLE, the most common include one or more of the following:
Shifting leg lameness (the most common sign of this disease)
Arthritis; polyarthritis (swollen, painful joints; non-septic; non-erosive; common)
Stiff, stilted gait
Loss of appetite (inappetence; anorexia)
Anemia (hemolytic); other bleeding problems
Skin lesions (redness; depigmentation; sores; pustules; vesicles/blisters), especially on the muzzle and in other areas exposed to sunlight
Secondary bacterial infections (pyoderma; common contributor to death)
Muscle wasting (atrophy)
Fever of unknown origin (fluctuating)
Pale gums and other mucous membranes
Hair loss (alopecia)
Thickened foot pads
Ulcerated foot pads
Enlarged lymph nodes (lymphadenopathy)
Enlarged liver (hepatomegaly)
Enlarged spleen (splenomegaly)
Increased water intake (polydipsia)
Increased urination (polyuria)
Neurological abnormalities (highly variable)
Signs of SLE can occur anywhere, including within the musculoskeletal system, skin, kidneys, liver, heart, lungs or other organs or organ systems. The symptoms can occur suddenly or slowly and can wax and wane over time. Often, the signs of SLE follow a cyclic pattern. Owners may notice their dog limping on a front leg, then returning to normal. Weeks or even months later, the same dog might begin to limp on a back leg, or on the other front leg. This sporadic lameness is attributable to swollen, painful joints.
Dogs at Increased Risk
Some breeds are predisposed to developing discoid lupus erythematosus, including Collies, German Shepherds, Siberian Huskies, Shetland Sheepdogs, Brittany Spaniels, German Shorthaired Pointers, Alaskan Malamutes, Chow Chows and crosses of these breeds. There is no age or sex predilection.
The mean age of dogs with systemic lupus erythematosus is 6 years, but it can occur in dogs of any age. German Shepherds are clearly overrepresented. Other breeds that are predisposed to developing SLE include Shetland Sheepdogs, Collies, Old English Sheepdogs, Afghan Hounds, Beagles, Irish Setters and Poodles.
Lupus – especially systemic lupus erythematosus - is not particularly easy to diagnose. The veterinarian must consider and rule out a number of other disorders that can mimic the symptoms of lupus before a diagnosis can be confirmed.
How Lupus is Diagnosed
Discoid lupus erythematosus (DLE) is less difficult to diagnose than its systemic counterpart. Usually, depigmentation of the skin on the nose, followed by the characteristic scaling, ulceration and crusting of facial skin, is diagnostic of DLE. Skin biopsies can be taken of non-ulcerated, depigmented facial areas for microscopic histopathologic examination.
Systemic lupus erythematosus (SLE) cannot be diagnosed based on any single test. The attending veterinarian must consider and exclude other possible causes of the dog's symptoms, such as pemphigus erythematosus, pemphigus foliaceus, cancer, tick-borne disease, kidney disease, bacterial/fungal/viral infection, musculoskeletal disorders and heart disease, among others. The results of a urinalysis and routine blood tests can vary widely based on the organ or organ systems affected by SLE. A skin biopsy and an antinuclear antibody (ANA) test can be helpful to confirm the diagnosis in many cases. A lupus erythematosus (LE) test is available to support the diagnosis, although the test is cumbersome and rarely used. Arthrocentesis can be used to sample joint fluid. Radiographs (X-rays) of affected limbs may disclose a non-erosive form of arthritis, which differs from the erosive lesions seen in dogs with rheumatoid arthritis.
It is important to rule out infectious causes of a dog's symptoms before treating it with immunosuppressive medications.
Two forms of lupus occur in domestic dogs: systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE). The effects of and treatment protocols for each form are very different. However, both are caused by an autoimmune disorder which essentially causes the dog's body to attack itself.
Treatment Options – Discoid Lupus Erythematosus
Discoid lupus erythematosus cannot be cured but is more manageable than the systemic form of the disease. The goals of treating DLE are to control and resolve the facial skin lesions, particularly on the hairless areas of the top of the muzzle. Treatment protocols may include oral or topical antibiotics, topical lotions or ointments, oral vitamin E, oral fatty acid supplements and oral or topical corticosteroids. Affected dogs should be kept out of the sun as much as possible, because the symptoms of DLE worsen with exposure to ultraviolet light. Owners can apply waterproof, high SPF sunscreen to their dog's face and ears to slow the progression of the disease. Dogs with DLE should be checked by a veterinarian regularly to assess their progress and to monitor the success of treatment. These dogs should not be used for breeding.
Treatment Options – Systemic Lupus Erythematosus
Systemic lupus erythematosus is also incurable. The goals of treating SLE are to manage the symptoms of the disease, relieve the dog from pain and lameness and prevent progressive renal or other organ failure if possible. Because the effects of SLE often wax and wane, not all cases need to be treated aggressively at all times. Dogs suffering from severe, acute-onset SLE may need to be hospitalized for initial management, until their condition is stabilized. There are a number of drugs that can be used to help manage SLE, including corticosteroids to suppress the abnormal immune reaction and non-steroidal anti-inflammatory drugs (NSAIDs) to reduce the inflammatory response. NSAIDs and steroids normally are not given in combination, because of the increased risk of gastrointestinal ulceration. Secondary bacterial skin infections should be treated aggressively with appropriate antibiotics.
Dogs with SLE usually require chronic chemotherapeutic treatment to suppress their immune systems and manage the painful symptoms of the disease. Often, a combination of steroids and other immunosuppressant drugs is used to combat the effects of lupus. Supportive care, enforced rest and dietary restriction to reduce protein intake may also be recommended. In most cases, SLE must be managed for life, although sometimes the daily dosage of medication can be tapered if the disease goes into remission. Long-term immunosuppressive therapy can have adverse side effects that should be discussed by the veterinarian and owner when designing a treatment protocol for a dog with SLE. These can include bone marrow suppression and a dramatically increased risk of developing severe infections, such as bronchopneumonia and urinary tract infections, among other things. Weight gain is also common with steroid use. Unfortunately, lifelong immunosuppressive therapy is the only viable method for managing SLE at the present time. There is no surgical option. Regular physical examinations, urinalyses and blood tests (complete blood counts and serum biochemistry profiles) should be conducted to monitor the side effects of chronic chemotherapy. Affected animals should not be bred.
The prognosis for dogs with DLE is fairly good, since the disease is rarely life-threatening. Dogs with DLE often go into remission and normally do not require chronic immunosuppressive therapy. Moreover, dogs with DLE usually seem to feel fine, even though the condition can be disfiguring and distasteful to their owners.
Unfortunately, given the unpredictable and progressively debilitating course of SLE, the prognosis for dogs with this form of lupus is guarded to poor.