Blastomycosis in Dogs
Blastomycosis is a fungal disease caused by Blastomyces dermatitidis, which is found in soil. The fungus is very difficult to detect in soil and there is no definitive way to remove it from the soil. In the United States, the disease is most prevalent in the warm, moist environment found in the Ohio and Mississippi River valleys. This fungus most commonly infects humans and animals through the respiratory tract. Once infective spores are inhaled, they settle in the lower airways and begin to reproduce. From here, the organism can spread through the bloodstream to involve other organs. Infrequently, infection can occur through inoculation of an open wound.
Symptoms will depend on which organs of the body are affected:
Blastomycosis can require specialized testing to diagnose. If skin lesions are present, sometimes the fungus can be detected by analyzing the wound discharge underneath of the microscopic (this test is called "cytology"). Xrays are done to assess the degree of disease within the lungs. Other tests may be necessary to look for evidence of the fungus in urine or blood samples.
Blastomycosis is a treatable disease, but not all pets will survive this serious infection. There is no way to determine survival before treatment is begun, although pets with advanced disease and in poor condition are less likely to recover. Antifungal medications are used to kill the blastomyces organism - many pets require therapy for several months. For many patients, the critical period comes in the first 24 to 72 hours when the fungal organisms begin to die. The lungs harbor a large number of organisms and a severe inflammatory response may occur as treatment takes effect. Relapse of the disease can occur even if the initial treatment appears successful. Additional therapies may include: antibiotics for secondary infections, oxygen therapy, fluid therapy, pain medications, and wound care.
Studies have found that once an animal is infected, the fungal organism enters a different form of its life cycle- this form does not appear infectious to other animals or humans. The infected pet does not need to be segregated from other household pets or humans; although through hand-washing should be prudent. The true risk of infection to others probably comes from sharing the same environment which infected the pet (i.e. the soil). We recommend discussing any health concerns with your family physician; especially if human family members are immunocompromised.
Symptoms will depend on which organs of the body are affected:
- fever, lethargy, weight loss, swollen lymph nodes, and decreased appetite are common
- respiratory symptoms may include coughing, nasal discharge, heavy breathing or respiratory distress
- skin lesions with drainage appear if the skin is infected
- blindness can occur if the eyes are infected
- lameness occurs if joints are infected
Blastomycosis can require specialized testing to diagnose. If skin lesions are present, sometimes the fungus can be detected by analyzing the wound discharge underneath of the microscopic (this test is called "cytology"). Xrays are done to assess the degree of disease within the lungs. Other tests may be necessary to look for evidence of the fungus in urine or blood samples.
Blastomycosis is a treatable disease, but not all pets will survive this serious infection. There is no way to determine survival before treatment is begun, although pets with advanced disease and in poor condition are less likely to recover. Antifungal medications are used to kill the blastomyces organism - many pets require therapy for several months. For many patients, the critical period comes in the first 24 to 72 hours when the fungal organisms begin to die. The lungs harbor a large number of organisms and a severe inflammatory response may occur as treatment takes effect. Relapse of the disease can occur even if the initial treatment appears successful. Additional therapies may include: antibiotics for secondary infections, oxygen therapy, fluid therapy, pain medications, and wound care.
Studies have found that once an animal is infected, the fungal organism enters a different form of its life cycle- this form does not appear infectious to other animals or humans. The infected pet does not need to be segregated from other household pets or humans; although through hand-washing should be prudent. The true risk of infection to others probably comes from sharing the same environment which infected the pet (i.e. the soil). We recommend discussing any health concerns with your family physician; especially if human family members are immunocompromised.
