Blastomycosis is a systemic fungal infection caused by the dimorphic fungus Blastomyces dermatitidis. The infective form of the organism, the mycelial phase, is most likely to be found in sandy, acidic soil near bodies of fresh water. High organic matter content in the soil from decaying wood byproducts or animal waste together with moist conditions promotes growth of the organism. Blastomyces dermatitidis has a relatively wide distribution. Blastomycosis is most commonly diagnosed in dogs and people