Bullous pemphigoid

In nature animals have evolved a sophisticated defence system that produces glycoproteins called immunoglobulins or antibodies in response to chemicals (antigens) on the surface of organisms (eg bacteria, viruses) or other substances (eg toxins) that gain access to the body. The antibodies chemically bind with the antigens - an initial step in the process to remove them from the body. Under normal circumstances the body's immune system recognises tissues and cells that are part of itself, and the immune system will only produce antibodies against foreign cells. However, sometimes the controlling mechanisms fail and the immune system does produce antibodies which attack the animals own body tissues. These are called autoantibodies and the disease that results is called an autoimmune disease.

Autoimmune blistering skin diseases have been recognized for decades in humans and dogs. Pemphigoids are a group of autoimmune skin disorders that affect the subepithelial level of the skin. Bullous pemphigoid (BP) is a very rare autoimmune blistering dermatosis that affects cats, dogs, and horses. Autoantibodies are directed at a skin glycoprotein called bullous pemphigoid antigen.

Bullous pemphigoid has been seen in Collies and Doberman Pinschers.

Generally, the vesicles (small blisters), bullae (large blisters) and ulcers do not spread and remain the same size as the previous bullae. Scarring is comon, but variable in severety. New bullae often develop within scarred lesions. Secondary bacterial infections are frequent. Vesicles are usually less than 1 cm in diameter and are fluid-filled sacs originating in the epidermis or dermis. Compared to vesicles, bullae are fluid-filled elevations of the skins larger than 1 cm in diameter. The fluid is usually clear and is composed of serum, but may be pink or red if blood is present. In BP, the bullae are tense and well defined.

The typical clinical course of BP is chronic but relatively mild. Most affected dogs have lesions in and around the mouth and around the eyes. Lesions also almost always are present at other locations including the armpits and the groin. Both acute and chronic form of the disease have been recognized. Dogs severely affcted with the acute form may be lethargic, lose appetite, have fever and appear depressed.

Diagnosis Immune mediated diseases are anincreasingly recognized group of diseases indogs and cats. They take a number of forms and may affect different organs of the body. Diagnosis of these diseases is often difficult and costly. Diagnosis is based on clinical signs, skin biopsy and immunologic testing. The lesions are erosive and often infected. They respond poorly to routine treatment for bacterial dermatitis which is the primary differential diagnosis.

Treatment The disease is usually treated with corticosteroids, but continuous treatment is often needed and the longtem outlook is poor. The disease may improve without treatment only to recur without cause. Following remission the therapy is gradually tapered, but this may frequently result in relapses. Treatment is usually lifelong and there maybe side effects from the medication just as life threatening as thedisease itself. Antibiotics are used if secondary bacterial infection is present. Topical glucocorticoids frequently are not effective. Key drugs and therapies for bullous pemphigoid can be found HERE.