WHAT IS BLASTOMYCOSIS?
Blastomycosis is a disease caused by a fungus in the soil, Blastomyces dermatidis. The organism is found in rich, acidic soil along the waterways of the Midwest and central United States.
In Minnesota, most Blastomycosis cases are found in St. Louis, Itasca, and Beltrami
counties, but more recently Chisago and Washington counties also. This disease must be reported to the Minnesota Department of Health. The disease can be deadly and affect the respiratory system, skin, eyes, bones, urinary system, and central nervous system. The incubation time is about 45 days and September is the most common month that it is diagnosed.
WHO IS AT RISK?
Dogs are most at risk for Blastomycosis. There were 907 cases of Blastomycosis of pets in Minnesota between 1999 and 2011. 97 % of the cases were dogs; 3 % were cats. The breeds most affected were Labrador Retrievers at 37%, Golden Retriever at 10 %, German Shepherd at 4%, Siberian Husky at 4 %, German Shorthaired Pointer at 2%, and Cocker Spaniel at 2%. Dogs like to roam around and dig in the soil, which exposes them to the fungus. Many of us have summer cabins and bring our pets, causing them to be exposed. People are susceptible to this disease also. It is seen more at construction sites when the soil is being disturbed. This disease is not contagious between hosts, whether they are dogs or people, and can only be contracted by being in contact with the fungal spores in the soil.
SIGNS OF BLASTOMYCOSIS
Signs of the disease include lethargy, anorexia, weight loss, cough, difficulty breathing, fever, skin lesions, lameness, blindness, heat seeking, and seizures. People will notice that their dogs are very sick. At the Westgate Pet Clinic radiographs can be taken which may show a characteristic pattern of inflammation in the lungs. If there are draining tracts in the skin, a slide made of the material and examined under the microscope may show the budding yeast. Enlarged lymph nodes can be sampled to show the yeast also. It is important to get a diagnosis as soon as possible in order to begin treatment.
TREATMENT OF BLASTOMCYCOSIS
Once a positive diagnosis is made, treatment is begun immediately with an antifungal medication, called itraconazole. This medication is very expensive and treatment can takes months to provide a cure. The medication is given daily until a negative urine test is obtained. To prevent relapse, at least two negative urine tests may be obtained before stopping the medication. There is no clear way to prevent infection except to stay out of areas that are known to have the fungus in the soil. Many pets (55%) can be cured with dedication to giving the medication daily as long as it is needed. Some pets will die if the symptoms are severe, especially lung infection. We have seen this disease at Westgate Pet Clinic in dogs that have been to northern in Minnesota or Canada.
by Doctor Rhonda Downie