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Blastomycosis (Fungal Infection of the Lung and/or Skin with Blastomyces Dermatitidis) in Dogs

Occurrence: rarer
Location of illness: General/Whole body

Author: Dr. med. vet. Gisa Löwe | Last modified: 06.11.2025

Blastomycosis is a fungal infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. in dogs caused by the fungus Blastomyces dermatitidis. This infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. mainly affects the lungs and can spread to the skin and other organs.

BASICS/CAUSES:

Blastomyces dermatitidis belongs to the class of dimorphic fungi, meaning it can exist in two forms: as a mold in the environment and as a yeast-like form in the host’s tissue. This fungus is mainly found in moist, soil and organic-rich soils, often near bodies of water. Regions with high prevalences are primarily known in North America, especially in areas around the Great Lakes, in the Ohio and Mississippi Valleys, and in southern Canada.

The infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. occurs when dogs inhale the fungal spores from the air. These spores transform into the yeast-like form in the dog’s body and multiply in the lung tissues. From there, the fungus can travel through the bloodstream or lymphatic system to other parts of the body, including skin, eyes, bones, and the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior..

Susceptibility to infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. can be influenced by various factors, including the dog’s immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body., age, breed, and specific environmental conditions. Certain dog breeds, such as hunting dogs, which are often active in moist, wooded areas, may be at higher risk.

The most important facts at a glance

Blastomycosis in dogs is caused by inhaling spores of the fungus Blastomyces dermatitidis, which are found in certain moist soils. Dogs with weakened immune systems are particularly at risk. Symptoms can include Cough, nasalNasal refers to the nose and nasal cavities. In veterinary medicine, this can involve examinations, treatments, or diseases affecting the nose of dogs and cats. discharge, skin ulcers, Fever, and enlarged lymph nodes. DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is challenging and often requires special tests, including chest X-rays, microscopy and cultures of samples, and serological tests. Treatment is mainly with antifungals such as Itraconazole and can take several months. In severe cases, intravenous treatment may be necessary. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. depends on the severity of the disease and the timing of diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients.. Without treatment, the disease can be fatal. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is difficult as exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to spores is not completely avoidable, but dog owners in at-risk areas should keep their animals away from moist, wooded areas. Research focuses on improving diagnostic and treatment methods, as well as possible preventive measures, including the development of vaccines. Research is also being conducted to determine whether certain dog breeds are genetically more susceptible to the disease, which could lead to targeted breeding programs in the long term.

Causes

InhalationInhalation is the act of breathing air or other substances into the lungs through the nose or mouth. In dogs and cats, inhalation of toxins, smoke, or allergens can lead to respiratory problems. of spores of the Blastomyces fungus, which are found in certain soils, especially in moist areas
Immunodeficiency due to diseases or medications can increase the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

The symptoms of blastomycosis can vary widely, depending on which organs are affected. General signs include Cough, respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, and Weight loss. These symptoms are common when the lungs are affected.

With skin involvement, dogs can develop Lesions that look like ulcers or nodules and often do not want to heal. These Skin changes are often seen on the nose, paws, or other exposed body parts.

If the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. spreads to the eyes, it can lead to eye discharge, redness, and in severe cases, Blindness. Bone involvement can cause Lameness, while involvement of the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior. can lead to neurological symptoms such as Convulsions.

Diagnosis

The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of blastomycosis often begins with a thorough clinical examination and the collection of the medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits., including questions about places of residence and possible exposures. Due to the variety of symptoms, a definitive diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is often challenging and requires special tests.

To confirm the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., imaging procedures such as chest X-rays are often used to identify signs of lung disease. Direct microscopy and culture of samples (e.g., from skin lesions or respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. secretions) can detect the fungus.

Serological tests that detect antibodies against Blastomyces dermatitidis in the blood can also be helpful, although they are not always reliable. In some cases, a biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions. is required to make an accurate diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients..

Therapy

The treatment of blastomycosis in dogs mainly consists of administering antifungals. Itraconazole is the most commonly used drug and is usually administered over a period of several months. In severe cases or when oralOral means "through the mouth" and refers to the intake of food, medication, or other substances through the mouth. In veterinary medicine, many treatments are administered orally. administration is difficult, intravenous treatment with Amphotericin B may be considered.

The treatment can be lengthy and often requires careful monitoring by the veterinarian to detect side effects and check the effectiveness of the therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions.. SupportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. measures, such as treating secondary bacterial infections or supporting the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body., may also be necessary.

Prognosis and follow-up care

The prognosis for dogs with blastomycosis depends on various factors, including the severity of the disease, the organs affected, and the timing of diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients.. With early diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and appropriate treatment, the prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is generally good, although the recovery time can take several months.

Some dogs may suffer relapses despite treatment or suffer permanent damage, especially if vital organs are severely affected. Without treatment, however, the disease is often fatal as it can lead to severe organ damage.

Prevention

The preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of blastomycosis can be difficult as it primarily depends on environmental factors. Dog owners in endemic areas should try to keep their dogs away from known sources of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., such as moist, wooded areas or places with organic-rich soils.

Since exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to fungal spores in the environment cannot be completely avoided, it is important to recognize early signs of the disease and seek veterinary help quickly. Regular veterinary examinations and awareness of the symptoms of blastomycosis can be crucial to detect the disease early and treat it successfully.

Outlook on current research

Current research on blastomycosis in dogs focuses on various aspects of the disease, including diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients., treatment, and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring.. A major focus is on improving diagnostic methods to identify the disease more quickly and accurately. Work is currently underway on molecular techniques that allow Blastomyces dermatitidis, the causative fungus, to be isolated directly from clinical samples. These methods could speed up diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and reduce the need for invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. procedures.

Another area of research is the development of new therapeutic approaches. Although antifungals such as Itraconazole are often used to treat blastomycosis, efforts are being made to find alternative drugs that are more effective and less toxic. Researchers are also exploring the possibility of modulating the immune responseAn immune response is the immune system's reaction to foreign substances (antigens), such as microorganisms or proteins. It involves a series of processes aimed at recognizing, fighting, and eliminating these antigens. of dogs to improve the chances of recovery by specifically strengthening the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. to fight the fungus more efficiently.

Preventive measures are also the subject of intensive research. Researchers are investigating environmental factors that increase the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. with Blastomyces dermatitidis in order to develop preventive strategies. These include studies on the distribution of the fungus in different geographic regions and the identification of environmental conditions that favor the growth of the fungus. The goal is to map risk areas and develop preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. measures that dog owners in these regions can take.

In addition, research is being conducted to determine whether vaccines against Blastomyces dermatitidis can be developed. This research is still in its early stages, but initialInitial means beginning or at the start. In medicine, it can refer to the first symptoms of a disease or the first phase of a treatment process. results are promising. An effective vaccineA vaccine is a substance that stimulates the immune system to develop immunity against specific pathogens without causing the disease itself. Vaccines may contain weakened or inactivated pathogens, toxoids, or recombinant antigens. could help reduce the incidenceIncidence refers to the number of new cases of a disease or condition that occur within a specific time period in a specific population group. It provides information about the risk of contracting the disease. of the disease, especially in areas with high prevalence.

Some studies are also examining the genetic susceptibility of dogs to blastomycosis. It is believed that certain breeds or genetic lines may be more susceptible to the disease. In the long term, this research could lead to the development of targeted breeding programs to reduce the prevalence of the disease.

Overall, research on blastomycosis in dogs is a dynamic field that is constantly providing new insights. Advances in diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients., treatment, and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. offer hope for more effective control of this often serious disease.

Frequently asked questions (FAQs)

What is blastomycosis in dogs? Blastomycosis is a fungal infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. caused by the fungus Blastomyces dermatitidis. It can affect the lungs, skin, and other organs of dogs, often with serious health consequences.

How do dogs get infected with Blastomyces dermatitidis? Dogs usually become infected by inhaling spores of the fungus, which are found in the environment, especially in moist, wooded, or swampy areas.

What symptoms does a dog with blastomycosis show? Common symptoms include Cough, respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, Fever, loss of appetite, Weight loss, and Skin lesions. Symptoms may vary depending on the organs affected.

How is blastomycosis diagnosed? DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made through a combination of clinical signs, X-rays, blood tests, and detection of Blastomyces dermatitidis in tissue samples or body fluids.

What treatment options are available for dogs with blastomycosis? Treatment usually includes antifungals such as Itraconazole. TherapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. can take several months, and additional measures may be required in severe cases.

What is the prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. for dogs with blastomycosis? The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. depends on the severity of the disease and the timing of diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients.. Early treatment improves the chances of a full recovery, but the disease can be fatal if left untreated.

Can humans get infected from dogs with blastomycosis? Blastomycosis is not directly transmissible from dog to human. However, both can be infected from the same environmental source.

Are there ways to protect my dog from blastomycosis? Avoiding areas where the fungus is found is one of the best ways to reduce the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. Regular health checks can also be helpful.

Which dog breeds are most susceptible to blastomycosis? Some studies suggest that large dog breeds such as Labrador Retrievers and Golden Retrievers may be more susceptible, but blastomycosis can affect dogs of any age and breed.

What role does the environment play in the spread of blastomycosis? Environmental conditions such as humidity, temperature, and soil conditions influence the spread of the fungus. Areas with moist soils and abundant organic material provide ideal conditions for the growth of Blastomyces dermatitidis.