The Disease Blastomycosis in Dogs

by Deborah Lundin
Hunting and sporting dogs have an increased risk for blastomycosis.

Hunting and sporting dogs have an increased risk for blastomycosis.

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If your dog loves to spend his leisure time digging up moist soil, knowing the signs and symptoms of blastomycosis is essential. Blastomycosis is a fungal infection caused by the Blastomyces dermatitidis. This fungus thrives in moist soil, especially in areas of fresh water throughout the Midwest and Southern states, such as Ohio and Tennessee. While treatment is available for blastomycosis, a proper diagnosis and early treatment is essential for a positive prognosis.

How Blastomyces Dermatitidis Spreads Disease

Blastomyces dermatitidis fungus resides in areas where decaying organic matter, such as leaves or wood, thrive. Moist, sandy soil near fresh bodies of water are another source. When your dog disrupts the soil containing this fungus, fungal spores release into the air. As your dog inhales, these spores travel into the lungs, where they take hold and reproduce. As reproduction begins, the fungus spreads throughout the body and can infect multiple organs.

Dogs With a Greater Risk of Infection

While blastomycosis can affect any breed, regardless of age or sex, certain breeds have a greater risk. Intact male dogs of large breeds and sporting breeds tend to have a greater risk due to roaming and increased exposure to environments where the fungus resides. In areas where Blastomyces dermatitidis thrive, such as Midwestern and Middle Atlantic states, the risk of infection increases. This is especially true if you live near areas of fresh water, such as a stream or lake.

What the Fungus Does to Your Dog

Symptoms associated with blastomycosis can vary depending on the area of the body infected. Common symptoms include fever, loss of appetite, weight loss, difficulty breathing and coughing. If the spores spread into the eyes, you may see discharge and inflammation. Skin lesions filled with a pus-like substance may also be present.

How to Treat Blastomycosis

Once your veterinarian diagnoses blastomycosis, treatment typically begins with oral antifungal medications, including itraconazole and fluconazole. In most cases, your dog will take this medication for a minimum of two months, with six months being the average treatment time. Medication must be administered for at least a month after symptoms go away. Because care occurs at home and lasts for many months, it is essential to follow all the medication directions given to you by your veterinarian. In rare cases, a relapse can occur. The risk for this is greatest when the spores infect the eyes, nervous system or testicles. In this case, removal of the eye or castration may be necessary.

Blastomycosis Can Infect You Too

Blastomycosis can occur in humans as well, though a direct spread between you and your dog is uncommon. If you treat weeping lesions on your dog’s skin, use gloves and care, especially if you have open cuts. Spores can transfer from one open wound to another. If your dog has no open wounds, the chances of you contracting blastomycosis from him are slim. However, if your dog develops blastomycosis, there is a good chance you may have encountered the spores from the environment as well. Symptoms in humans include fever, chills, cough, muscle aches and joint pain. These symptoms typically surface three to 15 weeks after exposure. If your dog is diagnosed with blastomycosis and you develop flu-like symptoms, it is a good idea to let your physician know.

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