Steroid-sparing effect of mycophenolate mofetil in the treatment of a subepidermal blistering autoimmune disease in a dog

A 7-year-old female Cocker spaniel-cross was referred with an 8-month history of mucocutaneous erosive dermatitis. On physical examination, skin lesions affected the eyelids and periocular area, lips and vulva. Lesions were symmetrical with small diffuse superficial ulcers, haemorrhagic crusts, adherent purulent exudation in haired skin, and alopecia with hyperpigmentation and scarring. Histopathologic evaluation showed multiple, non-intact dermoepidermal junction vesicles and ulceration associated with a dermal lichenoid infiltrate. Immunohistochemistry showed strong to moderate reactivity in the dermoepidermal junction for the antibodies directed against canine IgG, human IgG lambda light chains and C3, respectively. A diagnosis of autoimmune subepidermal blistering dermatosis was made. Treatment with oral prednisone at 2 mg/kg and mycophenolate mofetil (MMF) at 20 mg/kg twice daily was initiated and after 4 weeks the ulcers and erosions were cured. During the rest of treatment, MMF was maintained at 10 mg/kg twice daily and prednisone could be tapered to 0.25 mg/kg once every other day without recurrences. In conclusion, this case report shows that MMF was well tolerated and might be effective as steroid-sparing agent in the long-term treatment of this autoimmune subepidermal blistering disease.