Most Ohio Dog Owners Have Never Heard of It. That's the Problem.

• Read next: Histoplasmosis in Dogs: The Fungal Disease Ohio Dog Owners Need to Know About

• Also in this series: The Fungal Disease That Doesn't Care Where You Live

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There’s a fungus living in the soil along Ohio’s waterways right now. It doesn’t announce itself. It doesn’t leave a visible trace. And if your dog inhales it — which can happen in the time it takes them to bury their nose in a patch of wet ground — it can begin a chain of events that lands them in an emergency animal hospital, fighting for their life.

It’s called Blastomycosis. And most Ohio dog owners have never heard of it.

I hadn’t either — not really — until I saw a post in a Facebook group from someone whose young German Shorthaired Pointer was critically ill. I kept thinking about Gus, my own GSP, who spends every outdoor moment doing exactly what sporting dogs are built to do: nose down, moving fast, investigating everything. The post stayed with me. So did the research that followed.

This one’s worth knowing.

What Is Blastomycosis?

Blastomycosis is a serious systemic fungal infection caused by Blastomyces dermatitidis. It thrives in moist, decomposing soil — particularly near rivers, lakes, wetlands, and wooded floodplains. When that soil is disturbed, microscopic spores become airborne.

A dog doesn’t have to dig a giant hole to be exposed. Walking through wet ground, splashing near a riverbank, or simply doing an enthusiastic sporting-dog sniff can be enough to inhale the spores.

Once inside the body, the spores transform into a yeast form that colonizes the lungs and can spread through the bloodstream to the:

• Eyes

• Skin

• Bones

• Lymph nodes

• Brain and nervous system

This is not a minor infection. Blastomycosis can be fatal.

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Ohio Is Ground Zero

If you live in Ohio, you live in an endemic region. Blastomycosis is most common throughout:

• The Ohio River Valley

• The Mississippi River Valley

• The Great Lakes region

That’s not distant geography. That’s here.

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Activities that increase exposure risk include:

• Hunting

• Fishing

• Camping

• Digging

• Excavation

• Swimming in rivers and lakes

• Exploring wooded areas

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Research consistently shows that Blastomycosis occurs most often in young, large-breed dogs, with particularly high rates reported in:

• Coonhounds

• Pointers

• Weimaraners

In other words: sporting dogs, hunting dogs, and field dogs — the breeds that spend the most time in exactly the environments where this fungus lives.

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Why Blastomycosis Gets Missed

The dangerous part is that the early symptoms are incredibly vague.

Early signs may include:

• Coughing

• Lethargy

• Weight loss

• Swollen lymph nodes

• Fever

Those symptoms can easily look like a mild respiratory infection, kennel cough, or “maybe they’re just not feeling great today.”

As the infection progresses ...

Body System	Possible Symptoms
Lungs	Dry, harsh cough; labored breathing; respiratory distress
Eyes	Redness, discharge, cloudiness, vision loss
Skin	Raised or ulcerated lesions
Bones	Lameness, swelling, pain
Brain/Nervous System	Seizures, balance problems, neurological changes

About 85% of affected dogs show lung involvement.

And once neurological signs appear, the prognosis becomes much more serious.

IMPORTANT The takeaway: Do not wait. If your dog develops respiratory symptoms along with lethargy, fever, weight loss, or swollen lymph nodes — especially after spending time near water or in wooded areas — Blastomycosis deserves immediate consideration.

Diagnosis

Blastomycosis is often mistaken for:

• Pneumonia

• Cancer

• Other fungal infections

• General respiratory disease

Veterinarians may use:

• Physical exam and exposure history

• Chest X-rays

• Urine antigen testing (commonly through MiraVista Diagnostics)

• Blood work

• Cytology or biopsy of affected tissue

• Additional antigen testing if suspicion remains high

One of the most important things you can tell your veterinarian is where your dog has been. Geography matters enormously with fungal diseases.

Treatment

There is no quick fix.

Treatment typically involves 6–12 months of antifungal medication, most commonly Itraconazole.

Severe cases may require Amphotericin B, hospitalization, oxygen therapy, IV fluids, anti-inflammatory medications, and pain management.

One important detail many owners don’t know: The first 24–72 hours after starting treatment can actually be one of the most dangerous periods. As the fungus dies, inflammation in the lungs can temporarily worsen, and dogs with severe lung disease often need very close monitoring.

Prognosis: Honest Numbers

What studies show
Overall recovery with treatment	50–75%
Severe lung involvement during hospitalization	~50/50 survival
Three or more body systems affected	Poor prognosis
Central nervous system involvement	Often fatal
Relapse after successful treatment	~20%

Prevention: What You Can Do

There is currently no vaccine for Blastomycosis.

What you can do:

• Know when you’re in a high-risk area.

• Be cautious around freshly disturbed soil.

• Monitor your dog closely after outdoor activities.

• Call your veterinarian early if respiratory symptoms appear.

• Tell your vet about recent exposure to rivers, lakes, wetlands, or wooded floodplains.

For many sporting-dog owners, avoiding these environments entirely isn’t realistic. Awareness is often the most practical form of prevention.

Blastomycosis Isn't the Only Fungal Disease in Ohio

This is the part many veterinarians in endemic regions think about routinely: Blastomycosis is not alone.

Ohio dogs may also encounter:

• Histoplasmosis — often associated with soil contaminated by bird and bat droppings.

• Aspergillosis — which behaves very differently and can occur virtually anywhere.

They share an unfortunate trait: they often look like something else until they become severe.

A Quick Comparison

Feature	Blastomycosis	Histoplasmosis	Aspergillosis
Fungus	Blastomyces dermatitidis	Histoplasma capsulatum	Aspergillus spp.
Where it's found	Moist soil near rivers, lakes, wetlands	Soil contaminated with bird or bat droppings	Decaying vegetation, compost, hay, grain, moldy organic matter
Highest-risk dogs	Sporting and hunting breeds, young large-breed dogs	Sporting and hunting breeds, young large-breed dogs	German Shepherds (disseminated), dogs with heavy environmental exposure
How dogs are infected	Inhalation of spores	Inhalation or ingestion of spores	Usually inhalation
Primary organs affected	Lungs, eyes, skin, bones, lymph nodes	Lungs, GI tract, liver, lymph nodes	Nasal passages or multiple organs (disseminated)
Hallmark symptoms	Cough, fever, eye disease, lameness	Weight loss, diarrhea, fever, lethargy	Chronic nasal discharge, nosebleeds, facial pain (nasal) or vague systemic illness (disseminated)
Diagnosis	Urine antigen, imaging, cytology	Urine antigen, imaging, biopsy	CT/rhinoscopy, biopsy, fungal culture/PCR
Treatment	Itraconazole ± amphotericin B	Itraconazole ± amphotericin B	Topical antifungals for nasal disease; systemic antifungals for disseminated disease
Can it relapse?	Yes	Yes	Yes
Can it be prevented?	Reduce exposure; no vaccine	Reduce exposure; no vaccine	Reduce exposure; no vaccine

A Final Word

I don't share this to create panic.

I’m sharing it because I read about a young GSP puppy whose owner never saw this coming, and I immediately thought about Gus — nose to the ground, doing exactly what he was bred to do.

If this post causes even one Ohio dog owner to recognize the symptoms earlier, ask a better question at the vet clinic, or seek care a few days sooner, then writing it was worth it.

Know the name. Know the signs. Act fast.

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As always, this post is for informational purposes and is not a substitute for veterinary care. If you have concerns about your dog's health, contact your veterinarian.