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Blastomycosis, or “blasto” for short, is a fungal disease found in humans, dogs, and other mammals, occasionally cats. It is commonly misdiagnosed, often as cancer, Valley fever, Lyme disease, and other viral infections. It lives as a mold in warm (room temperature), acid, sandy soils near water. Once in the body, it lives as a yeast. It is contracted most often by inhaling through the nose the spores of the Blastomyces dermatitidis fungus. Blastomycosis is called a biphasic organism because it can grow in the environment as a fungus and within a mammal as a yeast.

In humans, blastomycosis is also known as Gilchrist’s disease, Gilchrist’s mycosis, Blastomyces dermatitidis, and Chicago disease.

Without proper diagnosis and treatment, Blastomycosis can be fatal.

For more information about Blastomycosis, visit

Blastomycosis in Dogs

Dogs are more susceptible because their noses are closer to the soil. It is believed that blastomycosis is more rampant during the fall season. Sporting and hunting breeds are the most often seen with blasto because of their frequent exposure to soil in wet areas. Young adults are more affected, but possibly just because that is the age group most often seen in hunting or field trials and on training grounds. For an unknown reason, one study has found that male dogs are more likely to contract it. Another study found that, while female dogs may have better survival rates with therapy, they are more likely to suffer relapses than males.

Blastomycosis has also been reported in other animals, including the horse, cow, cat, bat, and lion.

Symptoms include:

  • coughing
  • skin lesions, or small draining ulcer(s) on the skin, like a small abscess – draining bloody or purulent (pus) material
  • sudden blindness
  • lameness
  • blood in the urine
  • poor appetite
  • shortness of breath
  • fever that doesn’t respond to antibiotics – 103 degrees or higher
  • anorexia
  • depression
  • exercise intolerance
  • enlarged lymph nodes
  • eye problems: including redness, pain, swelling, excessive tearing, clouding of the corneas, and even blindness
  • listlessness
  • testicular inflammation

Disease Progression
Dogs often acquire blastomycosis after breathing in the spores from the soil through their nose and into their lungs. The skin lesions occur if the fungus get into the skin through an existing wound or puncture. In the lungs, it causes a pulmonary (lung) infection. It then spreads through the bloodstream or lymphatic system from the lungs to the eyes, brain, bone, lymph nodes, urogenital system, skin, and subcutaneous tissues.

After exposure to Blastomycosis, it may be weeks or months before you dog is showing symptoms. If a dog only inhales a few spores and is healthy, it is possible for his immune system to eliminate the spores. However if the amount of spores is great, or if the dog is immune suppressed or fighting another disease they will have a greater chance of taking hold within the lungs. As the single-celled yeast they become in the lungs, they can multiple rapidly.

To diagnose Blastomycosis, you need to get a positive sample of the blasto yeast from a lymph node or draining skin lesion or possibly by doing a lung wash, and maybe by sampling material coughed up by the dog. It is very difficult to get a positive sample, and there are many false positives and negatives when trying to diagnoses blastomycosis. A chest x-ray will confirm the symptoms, but not definitively diagnose the condition. Chest x-rays often show a “fluffy snowstorm” appearance to the lungs, which are the fungal organisms and associated inflammation.

One informational site says that “About 65 percent of dogs diagnosed with blastomycosis do survive. Because the treatment is long, complicated, and expensive with the potential for serious side effects, some owners elect to euthanize affected pets. In treated dogs, survival rates are approximately 85 percent, with up to 25 percent suffering relapses. Dogs with brain or eye involvement have a worse prognosis, and dogs with poor liver or kidney function may not be able to tolerate the necessary medications that must be metabolized by these organs. If an eye is involved, it usually must be removed since eyes don’t respond well to therapy and serve as a source of infection.” (source). Personally, and unfortunately, all the stories I have heard about blastomycosis in the last week have involved the death of the dog.

The treatment drugs of choice are amphotericin B, Ketoconazole and Itraconazole. Treatment is very expensive, and all figures I have read this week report costs incurred over $5000 Cdn. More information about these drugs for treatment, the use and side-effects can be found on this page
Even if the drug treatment is successful, it will not reverse any spinal or bone damage, or blindness. Even after treatment, the infection can remain dormant for many years and then reappear. However, after a year of remission without disease recurrence it is unlikely that your pet will have another occurrence of the disease.

There is no vaccine to protect your pet from blastomycosis. Avoidance of high-risk areas is the only thing you can do to lower your risk. Avoid areas of disturbed soil near water in areas where blastomycosis is common. Don’t allow your dog to dig in soil that may contain the fungus. Knowledge of the symptoms and existence of this disease will be your weapon should your dog ever begin to develop the symptoms mentioned above.

I lost my Golden Retriever, Surf, to what I believe was blastomycosis. Here is her story:

Surf’s Story

From Surf’s first cough until I had to let her go was only about 5 weeks. For the first 3 weeks she only had a cough. It really seemed like kennel cough. It was the characteristic cough-cough-cough-cough-long gag that I had read about kennel cough. It wasn’t too much of a bother. She didn’t cough at night, and at it’s peak it was only a couple times an hour. I didn’t want to infect other dogs by taking her to the vet as she seemed otherwise healthy. And I had just lost her older brother to mast cell cancer a few weeks earlier. I couldn’t let myself think my second dog could be sick too.

By week 3 when she started coughing up blood I was immediately worried and regretful that I hadn’t brought her to the vet’s earlier. The vet checked her over. She had a fever, but her lung sounds were normal. She coughed in the exam room, so he took a swab of the back of her throat to make a slide of it and check for anything definitive. He found lots of bacteria and cells indicating there was an inflammation and mucous. He mentioned blastomycosis then but said he didn’t see any on the slide. Her throat seemed sensitive to pressure, so he thought it could be an inflammation of her trachea, similar to kennel couch, and prescribed amoxicillin for 10 days.

Two days later she started turning down her food. Then she began to drag her back right paw and leg a little. I thought she had pulled her leg when she was trying to get off my bed, but it progressed to her right front paw as well. Then one night she just didn’t want to get up anymore. I had to start carrying her outside to pee because her legs just couldn’t navigate the stairs. I went back to the vet the next day, a week after her last visit. He couldn’t believe how fast she had declined. She still had a fever. He turned her right paws over one at a time to test her neurological responses. She couldn’t turn either of them back over to their proper position. He listened to her heart and chest for a long time, and then said he wanted to keep her to run full x-rays and blood work. When he called a couple hours later, he said she was anaemic, but worse yet, her lungs were completely full and that it was probably lung cancer. She coughed up a tablespoon of goop that they sampled and sent to a pathologist. I was absolutely devastated and wasn’t sure I was even going to bring her home from the vet’s. She was able to get up on her own and shuffle towards me, so I took her home. He gave her a shot of Baytril and I brought her home. She was not doing well.

For the next few days I stayed home from work and spent most of my time lying with her. Her breathing was fast and shallow. She would still drink on her own and pee when I carried her outside, but she was very still inside, only getting up to walk a few times a day. Sometimes she was too weak to lift her head. We tried so hard to get her to eat something, but she just wasn’t interested in any food. She wasn’t coughing much anymore. Two days after the night I took her back home from the vet, he called to say the pathologist found no cancer cells in the sample, or blastomycosis. Just lots of bacteria and dead cells because the sample might have been sitting in her upper respiratory system and wasn’t fresh. I thought we had a chance then. Surf had perked up a bit that day and ate a bit on her own. We put her on a heavy dose of Baytril (antibiotic). The vet wanted to do a lung wash or a lung biopsy to get a good idea of exactly what it was, in case it was blastomycosis, although he said he knew of a dog with similar symptoms who did have blasto. They sent him down to the University of Guelph for treatment, but $5000 in treatments later, he was just too sick and had to be put down. Surf was so weak by then, I knew she couldn’t handle the sedation for a lung wash. Two days later she could no longer walk, pee, eat, and she didn’t even show any joy when company showed up. My Dad and sister came to visit us and she didn’t even lift her head. Over the last 24 hours her temperature had fluctuated from being really really hot to much colder. Her stomach was distended. I really think her organs were all shutting down. I had to let her go. Absolutely heartbreaking…

I had heard of Blastomycosis being rather rampant in the Kenora, Ontario area. I had lived there for a summer and over the year following my work placement there, I started hearing new stories of dogs dying of it, and people contracting it from working near damp soil, like in their crawl space under a house or cottage, or under a porch. I had NO CLUE how widespread Blastomycosis is! Most information links about it report that it is mostly just in the Mississippi, Wisconsin, and Ohio River systems. However, I have since heard of it being here in Sault Ste. Marie, Ontario, as well as Chapleau and Timmins. I’ve read of it on the shores of Georgian Bay. I’ve also heard of it in New Brunswick. This fall (2005), it is rampant in Wisconsin.

The emergency vet on call who put Surf to sleep said she has seen several cases of Blastomycosis around here in the country, especially with hunting dogs and retrievers. She can’t understand why our local Algoma Health Unit says nothing about it.

I’ve learned that Blastomycosis can only be found in a very fresh sampling, which is why none of Surf’s swabs or phlegm slides showed it. She was always one to play at the shoreline when we took her for a swim. She dig in the muck for hours if I let her. I’m sure that is how she probably got it. If only I knew which lake…

Lisa Schuyler


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