Immune mediated diseases are an increasingly recognized group of diseases in dogs 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. 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, in which autoantibodies are directed at bullous pemphigoid antigen (skin glycoprotein). The condition has been seen in the Collie and Doberman Pinscher.
Generally, the vesicles (small blisters), bullae (large blisters) and ulcers do not spread and remain the same size as the previous bullae, with new bullae developing within scarred lesions. Scarring is common, but variable in severity. 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. Secondary bacterial infections are frequent. The typical clinical course of BP is chronic but relatively mild. Most affected dogs have lesions in and around the mouth, around the eyes, in the armpits and the groin. Both acute and chronic forms of the have been recognized. Dogs severely affected with the acute form may be lethargic, lose appetite, have fever, and appear depressed.
Diagnosis is based on clinical signs, skin biopsy, and immunologic testing. The erosive and often infected lesions respond poorly to routine treatment for bacterial dermatitis, which is the primary differential diagnosis. The disease may improve without treatment only to recur. 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 the disease itself.