Blastomycosis is a systemic fungal disease found primarily in the Missouri, Mississippi and Ohio River valleys. The Great Lakes region and eastern seaboard states report an increase of the fungal mold during the fall season. Finding out if blastomycosis occurs in your geographical region and seeking immediate veterinarian help upon recognizing the symptoms increases the dog's chance for successful treatment.
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Description
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Blasto fungus grows in moist, sandy soil rich in organic material. Proximity to water tends to be a key factor in the prevalence of these mold spores. Dogs inhale the fungal spores, which lodge in the lungs creating an infection. Once established in the lungs, it disseminates throughout the body affecting the skin, lymph nodes, eyes, brain and bones.
Risk Factors
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Exposure to soil in wet areas such as river valleys and lakes increases the risk for blastomycosis infection. As a result, hunting breeds such as pointers, retrievers and hounds have the highest rate of infection. Younger dogs, two to four years of age, tend to be in the higher-risk category. Male dogs show a greater risk of becoming infected than female dogs.
Symptoms
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Blastomycosis targets a dog's respiratory system first. As the fungus spreads through the lungs, lesions and nodules appear, making it difficult for the dog to breath. Watch for coughing, nasal discharge, harsh breathing and fever. Decreased appetite may lead to weight loss and weakness. As the fungus continues to spread, eye lesions and ulcerated skin lesions appear. If the dog has respiratory trouble and skin lesions, seek immediate veterinarian help.
Diagnosis
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Chest X-rays show the extent of lung lesions. Collecting scrapings from skin lesions produces a positive blastomycosis diagnosis about 50 percent of the time. Taking biopsies from enlarged lymph nodes or lung bronchi are only accurate about half of the time. Another diagnostic test is an antigen blood test, which detects antigens in the dog's urine, blood and spinal fluids. Immediate diagnosis and treatment is extremely important. Once the fungus has spread to the eyes or brain, treatment is almost completely ineffective.
Treatment
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The oral antifungal drug, Itraconazole, must be administered one to two times a day for two to three months. This drug is one of the most effective ways to treat blastomycosis, but cost is a large drawback. Itraconazole is currently the only home treatment. The remainder of the treatment options all require hospitalization. Amphotericin B is another antifungal drug option. Amphotericin B must be injected intravenously several times a week. Ketoconazole is another drug available to treat blastomycosis, but is not recommended by veterinarians due to its toxicity.
Follow-Up
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Continue veterinarian checkups after successful treatment. Twenty percent of dogs treated have a relapse. Relapses can occur up to 15 months after the treatment is ended. An additional round of treatment usually results in an 80-percent cure rate.
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