Blastomycosis in Dogs

What is Blastomycosis in Dogs?

Blastomycosis in dogs is a fungal infection caused by the organism Blastomyces dermatitidis. This fungus is commonly found in the environment, particularly in moist, wooded areas with acidic soil, such as riverbanks and lakeshores. Dogs can become infected with Blastomyces dermatitidis by inhaling fungal spores that are present in the soil or in decaying organic matter.

Once inhaled, the spores can transform into yeast-like organisms and cause a systemic infection in the dog's body, the incubation period in dogs is 5-12 weeks. Blastomycosis primarily affects the lungs but can also spread to other organs, including the skin, eyes, bones, and lymph nodes. 

How Common is Blastomycosis in Dogs?

Blastomycosis is a relatively rare fungal infection in dogs, but its prevalence can vary depending on geographic location. It is considered an emerging disease in veterinary medicine. Blastomycosis is caused by the fungus Blastomyces dermatitidis, which is found in the environment, particularly in regions with moist soil and decaying organic matter, such as wooded areas and near bodies of water.

The prevalence of blastomycosis in dogs is highest in certain areas of the United States and Canada, where the fungus is more common. These areas include the Mississippi River Valley, the Ohio River Valley, the Great Lakes region, and parts of the southeastern United States. In these endemic regions, blastomycosis is more frequently diagnosed in dogs.

However, in most other parts of the world, blastomycosis is rare in dogs. It is not considered a common canine disease on a global scale. Nonetheless, because the fungus can be found in various environmental settings, sporadic cases of blastomycosis can occur outside of the known endemic regions.

Is Blastomycosis in Dogs Contagious?

Dogs typically become infected with Blastomyces dermatitidis by inhaling the fungal spores from the environment. Once inhaled, the spores can lodge in the dog's lungs and cause an infection. It is not spread through direct contact between dogs or from dogs to humans. However, it's essential to note that the fungus exists in certain geographic areas, so dogs in those regions are at a higher risk of exposure. 

An infected dog could transmit blastomycosis to another animal through a bite, although this appears to be extremely rare.

What Causes Blastomycosis in Dogs?

Blastomycosis is a fungal infection that primarily affects dogs and other animals. Dogs are the most susceptible species to systemic infection with Blastomycosis. The disease is rarely reported in cats. The reason dogs are more susceptible is unknown, but immune-deficiency and the tendency to have their noses in the soil may play a role. 
Dogs can get blastomycosis when they inhale fungal spores from the environment, usually found in soil and decomposing organic matter near water sources like rivers and lakes. These spores can become airborne when the soil is disturbed, such as during digging or excavation.

Once inhaled, the spores can settle in the dog's lungs, where they can grow and cause infection. From the lungs, the fungus can spread to other organs like the skin, bones, and eyes through the bloodstream. The incubation period (time between exposure and development of signs) is from 5 to 12 weeks.

It's essential to be cautious when dogs are in areas where blastomycosis is prevalent, particularly in regions with a history of the disease. Early detection and treatment are crucial for a better prognosis, as blastomycosis can be a severe and potentially life-threatening condition if left untreated. That's why it's important to recognize the symptoms.

Signs of Blastomycosis in Dogs

Blastomycosis can affect various organs in dogs, making it a challenging disease to diagnose and treat. The symptoms can vary widely, but common signs include:

• Respiratory Symptoms: Coughing, wheezing, and difficulty breathing are often the first signs of blastomycosis. Dogs may develop pneumonia as the fungus primarily infects the lungs.
• Fever: Many infected dogs will run a high fever, which can persist for weeks.
• Loss of Appetite: A decrease in appetite is a common symptom, and some dogs may experience weight loss.
• Lethargy: Infected dogs often become lethargic and lack their usual energy.
• Skin Lesions: Blastomycosis can also cause skin lesions, which may appear as ulcerations, lumps, or pustules.
• Eye Problems: In some cases, the eyes may become inflamed, leading to discharge and discomfort.

How to Test for Blastomycosis in Dogs?

Diagnosis typically involves a combination of clinical signs, imaging studies (such as X-rays), and laboratory tests to identify the fungus or its DNA in affected tissues.

Blood Work

Blood tests can be helpful in diagnosing blastomycosis. A complete blood count (CBC) and serum chemistry panel can reveal abnormalities such as an elevated white blood cell count (indicating an inflammatory response) and changes in liver and kidney function.

Chest X-rays

X-rays of the chest can be essential in identifying lung involvement, which is common in blastomycosis. Chest X-rays may show characteristic changes such as nodules, infiltrates, or abscesses.

Fungal Culture

A definitive diagnosis of blastomycosis is often made through fungal culture. Tissue samples or fluids (such as pus) from affected areas, like skin lesions or lung secretions, can be cultured in a laboratory to identify the fungus. This can take several days to weeks.

Cytology

Fine-needle aspirates or biopsies of affected tissues can be examined under a microscope (cytology) to look for the presence of Blastomyces dermatitidis yeast forms. This method can provide a quicker diagnosis than fungal culture.

Antigen Testing

Some specialized veterinary laboratories offer antigen tests that can detect the presence of Blastomyces antigens in the dog's blood or urine. This can provide a rapid diagnosis, but it may not be as sensitive as other methods.

PCR (Polymerase Chain Reaction) Testing

PCR can be used to detect the DNA of Blastomyces dermatitidis in clinical samples. It is a sensitive and specific method for diagnosing the infection.

Histopathology

If biopsies are taken, histopathological examination of tissue samples can reveal characteristic changes caused by the fungus.

Treatment of Blastomycosis in Dogs

The treatment of blastomycosis in dogs typically involves a combination of antifungal medications and supportive care. 

Antifungal Medications

The primary treatment for blastomycosis in dogs is antifungal drugs. The most commonly used antifungal medication for blastomycosis in dogs is itraconazole. Other options may include fluconazole or amphotericin B. The choice of medication and the duration of treatment will depend on the severity of the infection and the dog's overall health.

Supportive Care

• Cough Suppressants: If your dog has a persistent cough, your veterinarian may prescribe cough suppressant medications to help alleviate discomfort.
• Fever Reducers: Dogs with blastomycosis often develop a fever. Fever reducers such as acetaminophen (under veterinary guidance) or non-steroidal anti-inflammatory drugs (NSAIDs) may be recommended to reduce fever and discomfort.

Cough Tabs are an antitussive and cough suppressant for temporary relief of cough symptoms in dogs.

Symptomatic Treatment

• Skin Symptoms: If your dog has skin lesions or sores, antifungal sprays or creams may be prescribed to treat the affected areas. Keeping the skin clean and dry is also important.
• Eye Symptoms: Anti-inflammatory eye drops or ointments may be prescribed if your dog has eye involvement due to blastomycosis. This can help reduce inflammation and discomfort.
• Hospitalization: In severe cases of blastomycosis, hospitalization may be necessary. Dogs with severe respiratory distress or organ involvement may require oxygen therapy, intravenous fluids, and close monitoring.

	Kills more than 650 kinds of bacteria and fungi in minutes. Penetrate 2mm subcutaneously for antibacterial purposes. Good for wound healing, skin renewing, and itching relief, having great antibacterial and anti-inflammatory effects. Nano-silver particles are applied with slow-release technology.
	The active ingredient in these eye drops is hydrocortisone acetate, which is a corticosteroid. Corticosteroids have anti-inflammatory properties and can help reduce swelling and itching in the affected area. It is designed to help alleviate discomfort caused by various eye conditions, including allergies, itching, redness, and swelling.

Nutritional Support

Ensure your dog receives proper nutrition during the treatment period. Some dogs with blastomycosis may experience a decreased appetite, so offering palatable, high-quality food can be important.

How to Prevent Blastomycosis in Dogs?

Preventing blastomycosis in dogs primarily involves avoiding exposure to the fungal spores. Since the fungus thrives in moist, acidic soil, taking the following precautions can help reduce the risk:

• Limit Outdoor Exposure: In areas where blastomycosis is prevalent, reducing a dog's outdoor activities in wooded or damp areas can minimize the risk of exposure.
• Regular Monitoring: Keep a close eye on your dog's health, and if any symptoms resembling blastomycosis appear, consult a veterinarian promptly.
• Educate Yourself: If you live in a blastomycosis-prone area, familiarize yourself with the disease's symptoms and prevention measures to ensure early detection and treatment.

Histoplasmosis vs Blastomycosis

Histoplasmosis and blastomycosis are both fungal infections that can affect dogs, but they are caused by different fungi and have some distinct differences:

Causative Agents

Histoplasmosis: It is caused by the fungus Histoplasma capsulatum.
Blastomycosis: It is caused by the fungus Blastomyces dermatitidis.

Transmission

Histoplasmosis: Dogs can acquire histoplasmosis by inhaling spores of Histoplasma capsulatum found in soil enriched with bird or bat droppings.
Blastomycosis: Blastomycosis is typically contracted by dogs when they inhale fungal spores from moist soil, especially near bodies of water.

Geographic Distribution

Histoplasmosis: It is more common in certain areas of the United States, especially in the Ohio and Mississippi River valleys.
Blastomycosis: It is prevalent in different regions, including the Great Lakes, Mississippi, and Ohio River valleys.

Clinical Signs

Histoplasmosis: Clinical signs in dogs may include respiratory issues, weight loss, lethargy, and gastrointestinal problems.
Blastomycosis: Dogs with blastomycosis often exhibit respiratory symptoms, skin lesions, fever, and can also have eye, bone, or joint involvement.

Diagnosis

Histoplasmosis and Blastomycosis: Diagnosis for both diseases involves detecting fungal elements in clinical samples (e.g., tissues, fluids) or through serological tests.

Treatment

Histoplasmosis and Blastomycosis: Both infections require antifungal medication for treatment. Medication choice and duration may vary depending on the severity of the infection.

FAQs

Is blastomycosis curable in dogs?

Blastomycosis in dogs is generally treatable with antifungal medications, such as itraconazole or fluconazole. Treatment typically lasts for 4-6 months, and it's important to follow your veterinarian's guidance regarding the duration and type of medication. Most dogs respond well to treatment and can recover fully,  with reported recovery rates up to 75 percent if the disease is caught early.

How long does Blastomycosis in dogs need to last?

The duration of treatment for blastomycosis in dogs can vary depending on the severity of the infection and the individual dog's response to treatment. It typically lasts for a minimum of several weeks to several months. Dogs with severe infections may require longer treatment periods.

Is blastomycosis in dogs fatal?

If left untreated, blastomycosis in dogs can be fatal. The disease can affect various organs, including the lungs, skin, eyes, and bones, and can lead to severe illness or even death. However, with prompt and appropriate treatment, the prognosis for dogs with blastomycosis is generally good, and most dogs recover.

When is Blastomycosis in dogs' timeline?

The timeline of blastomycosis in dogs can vary. The incubation period (time from exposure to the fungus to the development of symptoms) is usually around 2-15 weeks. Once symptoms appear, the disease can progress rapidly if left untreated. Early diagnosis and treatment are crucial for a better outcome.

Does blastomycosis go away on its own?

Blastomycosis is a fungal infection caused by the fungus Blastomyces dermatitidis. It typically does not go away on its own and requires medical treatment with antifungal medications. Without proper treatment, blastomycosis can persist and potentially become more severe.

Can a dog survive blastomycosis?

Yes, dogs can survive blastomycosis with appropriate treatment. Treatment typically involves antifungal medications, such as itraconazole or fluconazole, administered over an extended period. The duration of treatment can vary but often lasts several months. In some severe cases, hospitalization and intravenous antifungal therapy may be necessary. Surgery may also be considered in cases with extensive lung involvement.

Conclusion

Blastomycosis is a fungal infection that can pose a serious threat to dogs, especially in regions where the fungus is prevalent. Recognizing the symptoms, seeking prompt veterinary care, and adhering to the prescribed treatment plan are crucial steps in managing this disease. Additionally, taking preventive measures to reduce a dog's risk of exposure to Blastomyces dermatitidis is essential in ensuring their overall well-being. By staying informed and vigilant, dog owners can help protect their furry companions from the potential dangers of blastomycosis.