Blastomyces dermatitis is a dimorphic fungus which infects dogs, humans, cats, and horses, among other species. Infective spores are inhaled at which point the fungus transforms into an asexually reproducing yeast that infiltrates lung parenchyma and has potential for systemic spread. Clinical signs of blastomycosis reflect respiratory infection, systemic disease, and location of dissemination. A 4-year-old male neutered Boxer mixed breed dog from the Adirondacks presented to the Cornell Emergency Service on 2/28/14 as a referral for fever, inappetence, lethargy and non-productive, harsh coughing. He was found to have pleural exudate and cytologic evaluation of the fluid revealed Blastomyces dermatitidis organisms and a mixed inflammatory cell population. The patient was treated with long-term oral fluconazole and his clinical signs resolved within 5-6 months of the treatment. Prednisolone therapy was also initiated at the start of his treatment for a suspected inflammatory response to circulating fungal antigen.