Cutaneous neosporosis during treatment of pemphigus foliaceus in a dog

A 4-year-old, intact male rottweiler was presented with a 10-day history of papulonodular dermatitis. At the time of presentation, the dog was receiving prednisone and azathioprine to treat pemphigus foliaceus. Cutaneous neosporosis was diagnosed by immunohistochemistry on skin biopsy specimens and a high serum antibody titer to Neospora caninum by Neospora agglutination test. Electron microscopy examination of skin specimens further supported the diagnosis. Clindamycin therapy, together with withdrawal of immunosuppressive medication, resulted in prolonged clinical remission. This report documents cutaneous neosporosis in an adult dog and suggests that immunosuppressive therapy might be a predisposing factor.