Blastomycosis in Dogs
What is Blastomycosis?
Blastomycosis is a dangerous systemic fungal disease that can affect not just dogs but humans as well. Blastomycosis is caused by Blastomyces dermatitidis, a fungus that grows in areas where the soil is acidic, wet and rich in decayed foliage. Common areas for Blastomyces dermatitidis include streams, rivers lakes and even beaver dams. These conditions must be present in order for the fungus to survive.
It generally enters the body through the respiratory tract. It’s very hard to detect because the Blastomyces are not generally found in large widespread areas but rather in small pockets. When dogs inhale the fungal spores, they make their home in the small airways and commence to reproduce and spread throughout the entire respiratory system.
What Dogs are Susceptible?
Although blastomycosis can affect humans, dogs are ten times more likely to get this disease. Dogs that are the most susceptible to developing blastomycosis are those that live within 400 yards of a body of water or spend a lot of time near water, such as hunting and sporting dogs.
Other dogs highly at risk of developing this disease are intact male large breed dogs living in or near wet areas. When the area that holds the fungus is touched, the fungus spores are transferred to the air where the dogs can inhale it.
Once they inhale it, it travels to their lungs, which generally results in a respiratory infection. If the infection becomes serious, the disease can spread from the lungs to other organs of the body. Blastomycosis may start as a respiratory disease that affect the lungs but can also affect the bones, brain, eyes, skin, tissues and lymph nodes.
How is it Diagnosed?
We may think that once the dog develops the disease it would be easy to diagnose, but that’s not the case because dogs may not show clinical symptoms for weeks or months even though they may be infected with blastomycosis. Symptoms of blastomycosis include:
- Skin lesions
- Oozing lesions on the mouth, nose or paw pads
- Weight loss
- Shortness of breath
- Intolerance to exercise
- Eye diseases
- Enlarged lymph nodes
Diagnoses, which are usually made in the late summer or early fall, involve the following.
- Full blood count
- Serum chemistry test
- Thoracic radiographic examination
- Cytologic examination of infected tissues and cells
- Urinary antigen test
- Serologic test
- Polymerase chain reaction test
Of all the tests, cytology is the most effective in diagnosing blastomycosis. A tissue sample is sent to a laboratory to determine if the organism is present in the body. A screening blood test is also highly effective and commonly used for diagnosis purposes.
In certain cases, diagnosis may be difficult because so many of the symptoms of blastomycosis are also found with other diseases. If a dog has some blastomycosis symptoms but does not live in or frequent wet areas, the vet may not even suspect blastomycosis at first.
How to Treat
Treatment for blastomycosis is medication under the supervision of a veterinarian. Itraconzole, an antifungal drug, is the most common treatment choice and is generally given to the dog for at least two months or until the symptoms of the disease are gone. If the dog has a more serious case, the dog may also be given both Itraconzole and Amphotericin B.
Additional medications for blastomycosis include Voriconazole, fluconazole and ketoconazole. The prognosis is best for dogs that have little or no lung damage and worst for dogs whose central nervous system is infected. Follow up urine tests are recommended to ensure the treatment has been successful. Approximately 70 percent of dogs with blastomycosis who were diagnosed and treated early survived. However, about 20 to 25 percent of these dogs have relapses within the first year.
How to Care for a Dog with a Blastomycosis
Caring for a dog with blastomycosis can be difficult because it can affect so many different parts of the body. Lymph nodes, tissue and skin are affected in about 50 percent of dogs affected by blastomycosis. Approximately 30-50 percent of affected dogs develop glaucoma, blindness and retinal detachment. If there is one positive about this serious disease, it’s that blastomycosis is not contagious.
The first and most important way to care for the dog is to follow the vet’s recommendations and keep up with all follow up visits so the treatment and disease can be monitored. Treatment can take from six months to a year so it’s important to stick with it and follow all medical recommendations. It is also in the dog’s best interest to keep him or her out of wet areas as much as possible.
What to Do if You Suspect Blastomycosis
The best recipe for successful treatment of blastomycosis is early diagnosis and aggressive treatment. One of the most common and first signs owners notice is that the dog appears to have difficulty breathing. The dog may also suffer from intermittent coughing and may have a dry and raspy chest cough. If the dog exhibits these symptoms or any symptoms that may be consistent with blastomycosis, it’s imperative to get the dog to a veterinarian as soon as possible.