Canine perianal furunculosis and interdigital lesions: Probable systemic lupus erythematosus

Abstract

The clinical signs of systemic lupus erythematosus (SLE) are not specific. The classification of signs according to their diagnostic importance from major to minor signs has proved to be useful, and when employed together with serological and immunohistochemical tests can lead to an accurrate diagnosis. Skin lesions are classified among the major signs corresponding to about 15% of lesions under the suspicion of SLE in dogs. A 5-year old German shepherd dog that was presented to clinical examination had developed perianal fistulas and infectious interdigital dermatitis. The dog was treated with antibiotics for 3 months and did not improve. Clinical signs included skin changes: alopecia, erythema, depigmentation, pain, ulceration and granulation tissue in the perianal zone and limbs, and articular changes: carpal and tarsal joint effusion and pain during the evaluation of forced flexion/extension. Histopathology from perianal and interdigital zones of affected skin revealed partial separation of epidermodermal junction and presence of cellular debris, moderate vacuolization of epidermal basal cells, and abundant dermal histiocytic and lymphoplasmacytic inflammatory infiltrate and collections of eosinophils in blood vessels. The Peryodic acid Schiff (PAS) reaction showed basal membrane discontinuity in diseased skin and partial thickening in both affected and healthy skin. Both affected and healthy skin revealed immunoreactions of IgM, IgA and C₃ but not of IgG at the epidermodermal junction. According to clinical, histopathology and immunohistochemistry evidence we suggest that the present report is a probable case of SLE.