The spore form of the fungus lives in the environment. From there it is inhaled into the alveoli of the dog's lungs. Depending on the animal's immune system and the amount of spores inhaled, the dog may either clear the infection or it will spread throughout the body. A dog infected with blastomycosis can show many signs. The dog may have a fever, lose weight, and go off feed.
Respiratory signs are most common, including coughing and respiratory distress.
The dog may also have skin lesions and draining open sores. These skin lesions are often ulcerated and have a clear to bloody discharge. Blastomycosis can cause rapid changes in the eyes. Pain, swelling, redness, excessive tearing, clouding of the corneas, and even blindness may result from this fungal infection. To detect blasto, your veterinarian may want to radiograph the lungs in addition to looking at samples of skin lesion drainage under a microscope.