An 18-month-old female ferret with an ulcerated metacarpal pad and signs of respiratory illness was diagnosed as having blastomycosis by visualization of organisms on a tissue imprint, an agarose gel immunodiffusion test, and thoracic radiography. The ferret was treated intravenously with amphotercin B at 0.4 to 0.8 mg/kg and orally with ketoconazole at 8 mg/kg for approximately 1 month, during which time clinical and radiographic improvement was noted. A change to SC amphoterocin B therapy resulted in relapse of clinical signs despite continuation of ketoconazole therapy, and necessitated euthanasia. Necropsy revealed granulomatous lesions typical of Blastomyces dermatitidis infection in the lungs, thoracic pleura, spleen, meninges, and brain. Comparisons between this case and canine blastomycosis cases are made and alternative treatment regimes for mustelid blastomycosis are suggested.
