Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

Blastomycosis in Dogs

What Is Blastomycosis in Dogs?

Blastomycosis, also known as “Blasto,” is a systemic disease caused by the fungus Blastomyces dermatitidis, affecting the entire body. The fungus thrives in soil rich in moisture and decomposing organic matter like leaves and feces, commonly found in areas near water bodies.

Originating as mold in the environment, the fungus generates spores—tiny reproductive cells dispersed into the air when the soil is disturbed. Dogs can inhale these spores or have them embed in their skin, leading to blastomycosis.

Once inside a host’s warm body, the spores transform into budding yeast, primarily colonizing the lungs or skin. From there, the infection can spread to the bloodstream and other organs. The lungs, skin, eyes, bones, lymph nodes, brain, and testes are commonly affected. Less frequently, the prostate, liver, mammary glands, and heart may also be targeted.

As the disease advances, the yeast spreads to additional organs. When three or more organs are involved, the prognosis for the dog usually deteriorates. However, if caught early with mild symptoms, most dogs respond well to treatment.


The symptoms of blastomycosis vary depending on the organs affected. Approximately 85% of cases initially present with a dry, harsh cough, while up to 50% may exhibit skin nodules accompanied by pus. Owners of dogs residing in or frequenting areas near water bodies should be vigilant for the following signs:

  • Respiratory issues, including coughing, difficulty breathing, and nasal discharge (especially bloody discharge)
  • Draining skin nodules or lesions
  • Fever
  • Swollen lymph nodes
  • Weight loss or decreased appetite
  • Eye problems like inflammation, blindness, or swelling
  • Urinary problems, such as bloody urine, difficulty urinating, or enlarged testicles in males
  • Neurological symptoms like head tilts and seizures
  • Lameness or limping

In most instances, skin lesions and respiratory issues are the earliest indicators of blastomycosis in dogs.


Blastomycosis usually develops when dogs inhale airborne spores of the fungus from disturbed soil contaminated with the fungus. Sporting or hunting dogs face higher risks due to frequent exposure to such contaminated areas. Additionally, the spores can penetrate the skin. Regions with water and decomposing material, or those recently disrupted by construction activities, elevate the likelihood of exposure to the disease.


Veterinarians employ a comprehensive physical examination and detailed history to diagnose blastomycosis in dogs. Given its potential to mimic other conditions, veterinarians must exclude common ailments during diagnosis.

Diagnostic steps may include:

  • Blood tests
  • Imaging techniques like radiographs, ultrasound, or CT scans to assess lung condition
  • Urinalysis to detect yeast presence
  • Cultures
  • Serology
  • Biopsies

Definitive diagnosis entails identifying the organism in tissue samples obtained through biopsies or aspirations from skin lesions. (Aspiration involves collecting a small sample from an area via a needle for further analysis.)

Providing information about your dog’s recent whereabouts, especially in high-risk exposure areas, is crucial for accurate diagnosis. Mentioning any recent vacations or trips with your pet can aid the diagnostic process.


The treatment of blastomycosis in dogs typically involves oral administration of antifungal medications. This treatment regimen often spans several months, and if the condition is not severe, it can be managed at home.

Dogs experiencing breathing difficulties may necessitate oxygen therapy and hospitalization until their condition improves. In severe cases or instances where oral medication proves ineffective, extended hospital stays, intravenous medications, and additional medical care may be necessary.

For dogs with severe eye involvement, topical medications may be required, and in extreme cases, surgical removal of the affected eye might be necessary.

Living and Management

Preventing blastomycosis entails avoiding areas where the fungus might be prevalent, as there’s no foolproof preventive measure. With prompt treatment initiation and proper medication adherence, the prognosis for most dogs is favorable once symptoms manifest.

Pets with severe lung disease may initially appear worse as the fungal organisms perish. Improvement may take one to two weeks post-treatment initiation, necessitating close monitoring despite any underlying conditions.

Brain involvement often leads to seizures, which may be uncontrollable and fatal. When the disease spreads to more than three body systems, the prognosis tends to be grim. Relapses can occur in severe cases or if treatment is prematurely discontinued, typically within the first 6 months post-treatment.

Recovery doesn’t guarantee full immunity, and routine veterinary appointments, including annual exams, remain crucial for ensuring your pet’s ongoing health and well-being.

Blastomycosis in Dogs FAQs

What is the life expectancy of a dog with blastomycosis?

Without long-term treatment, the prognosis for dogs with blastomycosis is poor. The disease will continue to advance without intervention.

Can blastomycosis be transmitted to humans?

Blastomycosis cannot be transmitted to humans from dogs through airborne means like breathing or coughing. However, transmission via blood, such as through a dog bite, is possible. Proper precautions, including the use of gloves, should be taken when changing and disposing of bandages and bandage materials. This is especially important for individuals with compromised immune systems, as there is a risk of inhaling the fungus present on bandages.

How did my dog contract blastomycosis?

Dogs can contract blastomycosis when they inhale or come into contact with spores from soil contaminated with the fungus. Disruption of contaminated soil releases the spores, which can then be inhaled or penetrate the skin.

Scroll to Top