Blastomycosis is a systemic fungal infection caused by the dimorphic pathogen Blastomyces dermatitidis. B. dermatitidis grows as a mold in moist soil or vegetation that, under certain conditions, releases spores that can be inhaled by nearby animals or people. Once they enter the lungs, the spores transform into large thick walled broad-based budding yeast that multiply within the lung and other tissues of the infected animal. If it continues to multiply in the lung, blastomycosis can cause significant pulmonary disease (pneumonia) in animals and people. The yeast also have a tendency to disseminate to other sites in the body, particularly to the skin, eyes, and joints in dogs, and sometimes to the skin in people. For more information about blastomycosis, click on the links to the right.