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Autoimmune Skin Disorders |  |
| In these immunologic skin disorders, antibodies are directed against intracellular cement substances at the basal cell layer, which results in separation of the epidermal cells (acantholysis).
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Pemphigus foliaceus is more common in dogs than in cats and horses but is still an uncommon disease. It is characterized clinically by erosions, ulcerations, and thick encrustations of the skin and mucocutaneous junctions. The absence of lesions in the mouth, and the widespread thick, crusty nature of the skin lesions, tend to differentiate pemphigus foliaceus from pemphigus vulgaris. Autoantibodies are present in the skin and react with intracellular cement substance.
These autoantibodies cause a separation of the cornified from uncornified cell layers. High doses of glucocorticoids are used initially, but low-dose, alternate-day therapy is used once the disease is under control. More potent immunosuppressive drugs such as cyclophosphamide or azathioprine are used with glucocorticoids in cases unresponsive to steroids. Gold salts, in conjunction with low doses of glucocorticoids, are sometimes helpful in maintaining remission in animals in which
steroids alone are ineffective. Animals that respond poorly to initial therapy, or require high dosages of drugs to control lesions, have a poor longterm prognosis. |
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Pemphigus vulgaris is rarer than pemphigus foliaceus. It is characterized by bullous lesions along the mucocutaneous junctions of the mouth, anus, prepuce, and vulva, and in the oral cavity. Other areas of the skin are only mildly involved. Because the epidermis of animals is relatively thin (compared with human skin), the bullae rupture rapidly and form erosions; consequently, characteristic bullae are seldom seen. The bullae occur as a result of suprabasilar
acantholysis. Secondary bacterial infection often complicates the lesions, and if untreated, the disorder is often fatal. It is treated with high doses of glucocorticoids alone or in combination with other drugs such as cyclophosphamide, azathioprine, or gold salts. The disease is difficult to maintain in remission, and the longterm prognosis is fair to poor. |
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Bullous pemphigoid has been recognized in dogs, most often in Collies and Doberman Pinschers. Lesions are often widespread but tend to be concentrated in the groin. The involved skin resembles a severe scald. Bullae also may be seen; they are subepidermal and may be full of eosinophils. Autoantibodies to the basal lamina proteins are seen in immunohistopathologic sections. The treatment of choice is prednisolone and azathioprine used in combination; remission is
frequent, but continuous drug therapy at relatively high dosages may be required to keep the disease under control. The longterm prognosis is poor. |
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