Although autoimmune dermatoses are relatively uncommon in dogs and cats, they are important because of their severity and propensity for causing systemic illness. The pemphigus complex of diseases are the more common autoimmune diseases. Pemphigus foliaceous results when autoantibodies are directed against an epidermal antigen. The primary lesions are papules and pustules. Foot pads may be hyperkeratotic with excessive build-up of crust with fissures. The differential list is long, but pyoderma is the most common disease with similar characteristics. If there is mucosal or mucocutaneous involvement, pemphigus vulgaris is more likely. Discoid lupus erythematosus is more common in specific breeds, including collies, Shetland sheep dogs, German shepherds, German shorthaired pointers, Siberian huskies, and Brittany spaniels. Classically, there is nasal depigmentation with subsequent erosion and crusts. Exposure to sun aggravates the condition.

Treating autoimmune dermatoses involves focusing on 3 phases: acute, maintenance, and supportive. Most patients require therapy for the remainder of their lives. Glucocorticoids at immunosuppressive doses are first-line therapy in the acute phase and may be sufficient for maintenance in some cases. Other immunosuppressive therapy includes azathioprine, cyclophosphamide, chlorambucil, and chrysotherapy (gold). Vitamin E has also been reported to have some beneficial effect.

Commentary: Although some forms of pemphigus are relatively benign, some, especially pemphigus vulgaris, may be fatal. Patients with vulgaris may have a positive Nikolsky sign (the skin is loose and when rubbed, slips free creating a new lesion). Patients will require lifelong treatment.

Diagnosis and treatment of common autoimmune skin diseases. MacDonald JM. WILD WEST VET CONF, October 2003.