Systemic Lupus Erythematosus in Dogs: Systemic Aspects

Systemic Lupus Erythematosus in Dogs: Systemic Aspects

Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO

BASIC INFORMATION

Description Systemic lupus erythematosus (SLE) is an autoimmune disease that arises when the body's immune system attacks multiple tissues or organs in the body, as if they were foreign. SLE may involve the joints, skin, kidneys, platelets, and red blood cells. Most affected dogs are young to middle-aged. Dogs of many breeds can develop SLE, but the German shepherd dog appears to be predisposed. Causes In SLE, antibodies are produced that form complexes with antigens (proteins) on or in the body's cells. These immune complexes become trapped in the blood vessels of certain organs, such as joints and kidneys, and cause an inflammatory reaction. The body's attempts to deal with the inflammatory reaction actually make the situation worse. It is not known why the body creates antibodies against its own tissues.

Clinical Signs

Vague signs may develop initially, such as weight loss, lethargy, poor appetite, and mild lameness. Dermatologic signs occur in about 33% of affected dogs. (See the handout on Systemic Lupus Erythematosus: Dermatologic Aspects.) Polyarthritis, which is inflammation in multiple joints, develops in about half of dogs with SLE and manifests as lameness, pain, and swelling of the joints. (See the handout on Immune-Mediated Arthritis.)

Dogs with kidney involvement may have no clinical signs initially. If significant kidney damage develops, then increased thirst and urination, muscle wasting, nausea, and vomiting may be seen. (See the handout on Protein-Losing Nephropathy in Dogs.) An immune-mediated hemolytic anemia occurs in about 30% of dogs with SLE, and platelets may also be affected. Associated signs include weakness and pale gums from anemia and widespread hemorrhages on the gums and skin from poor blood clotting. (See also the handouts on Immune-Mediated Hemolytic Anemia and Immune-Mediated Thrombocytopenia.)

Diagnostic Tests

Routine blood and urine tests are usually recommended and may show multiple abnormalities such as anemia, low platelet count, elevated protein levels in the blood and urine, and mildly altered kidney function. X-rays of the joints and abdomen may be indicated, depending on the clinical signs. An ultrasound of the abdomen is helpful to examine the kidneys. If excessive protein (proteinuria) is found in the urine, additional urine tests may be recommended. (See the handout on Urine Protein Assays in Dogs.)

Several immune assays may be performed, such as a lupus erythematosus (LE) clot test, antinuclear antibody assay (ANA), and Coombs' test. Immunologic tests may also be performed on biopsies of skin, kidneys, and joint tissues. Fluid may be aspirated from inflamed joints and sent for analysis and culture.

The diagnosis of SLE is difficult, because no single test is available that indicates the presence of the disease. Additional tests may be recommended to rule out other diseases that can cause similar signs and laboratory findings, which include infections, other immune diseases, drug reactions, and certain cancers. Making a diagnosis of SLE depends on eliminating these diseases and documenting at least one positive immunologic test and involvement of at least two different organ systems.

TREATMENT AND FOLLOW-UP

Treatment Options

Corticosteroid drugs, such as prednisone, are the most common treatment. High, immune-suppressive doses are usually needed to bring the disease under control, so it is important to rule out the presence of infectious diseases prior to starting therapy. Once clinical signs improve, the prednisone dosage may be tapered.

If the dog does not respond well to prednisone alone, stronger immune-suppressant medications, such as azathioprine, cyclosporine, and cyclophosphamide, may be added to the therapy. Other medications, supplements, and dietary changes may be recommended to help alleviate proteinuria, joint pain, vomiting, weight loss, and other signs.

Follow-up Care

Long-term monitoring is needed of both the disease and potential side effects of the medications used to treat it. Prednisone commonly increases appetite, thirst, and urinations and causes weight gain and secondary effects on the liver. The stronger immune suppressants can produce adverse effects on blood cells and on liver and kidney function. Periodic recheck visits and repeated laboratory tests are typically needed for the life of the dog. Prognosis SLE is a chronic, progressive disease that is difficult to control. Many pets do not respond to therapy or respond only partially (for example, the skin improves but the kidney disease does not). Sometimes response occurs early on but, as time goes by, the disease becomes harder to control. If kidney damage occurs and the kidneys begin fail, the prognosis is poor and survival times are usually short.

IF SPECIAL INSTRUCTIONS HAVE BEEN ADDED, THEY WILL APPEAR ON THE LAST PAGE OF THE PRINTOUT. Copyright ? 2011 by Saunders, an imprint of Elsevier Inc. All rights reserved.

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