Dogs are susceptible to a variety of infections, and one of those is blastomycosis. This fungal infection can be deadly if left untreated, so knowing the symptoms and treatment options is essential. In this post, we'll discuss what blastomycosis is, how it's contracted, and the symptoms to look for in your dog. We'll also provide some treatment options for this serious infection. So keep reading to learn more about blastomycosis in dogs!
What is blastomycosis in dogs?
Blastomycosis in dogs is a fungal infection caused by blastomyces dermatitidis. This fungus is found in soil and organic matter and can affect many animal species but mainly dogs and humans. While it primarily affects the respiratory system, it can also involve other organ systems. The fungus is more likely to grow in areas where there are natural water sources, and moist, acidic soils rich in decaying vegetation. Infection occurs when the fungal spores are inhaled and the incubation period in dogs is 5-12 weeks.
The following are common areas in North America where blastomycoses fungal organisms can be found: mid-Atlantic states, Ohio, Mississippi, Tennessee, Missouri, and St. Lawrence River valleys, Great Lakes Region; as well as Manitoba, Quebec, and Ontario in Canadian regions.
What are the symptoms of blastomycosis in dogs?
Blastomycosis organisms have an affinity for the respiratory tract, and lung disease is the most common disease manifestation in the majority of cases in dogs. Respiratory symptoms such as cough, increased respiratory rate, increased breathing sounds, and respiratory distress are the most common.
Ocular lesions are also common sequelae of blastomycosis in dogs and include ocular redness, squinting and ocular discharge as blastomycosis can cause anterior uveitis. This can be severe enough to result in blindness.
Non-specific symptoms can include fever, lack of appetite, lymph node enlargement, draining skin lesions and lameness due to joint inflammation.
How is blastomycosis diagnosed in dogs?
A diagnosis of blastomycosis can be difficult as the symptoms are often nonspecific and can be caused by other infections. A combination of tests is typically used for diagnosis which may include a complete blood count, biochemical blood profile, urinalysis, chest radiographs, antibody testing, and cytology.
The urine blastomyces quantitative antigen (EIA) test is very accurate, with a reported sensitivity of 100%. However, it is possible for the test to give false-positive results for other types of fungi.
In most cases of blastomycosis in dogs, the chest radiographs are abnormal, even in dogs that don't have any respiratory symptoms. The classic finding on a radiograph for this condition is called a diffuse or generalized "snowstorm" pattern.
What are the treatment options for blastomycosis in dogs?
The treatment for blastomycosis in dogs includes the use of antifungal drugs. Itraconazole is the drug of choice and is effective in the majority of cases. Itraconazole is well tolerated by dogs with minimal side effects. The usual course of therapy is 3-6 months to be effective and curative. Veterinarians will recommend treating for at least 1 month past clinical resolution of symptoms. It is also recommended that itraconazole be given with food for maximum absorption.
Alternatively, fluconazole can be used but it is less effective than itraconazole. The benefit however is that it is less expensive and has fewer side effects than that of itraconazole. Also, a longer course of therapy is often required when treating blastomycosis with fluconazole compared to that of itraconazole.
Amphotericin B can also be used but is usually only used for very severe blastomycoses infections that result in central nervous system symptoms. The treatment duration is much shorter compared to antifungal drugs, but there is an increased risk of renal damage.
What is the prognosis for dogs with blastomycosis?
The prognosis for most cases of blastomycosis in dogs is quite good, with reported recovery rates up to 75 percent if the disease is caught early. The outlook is much worse when central nervous system involvement occurs since seizures are common upon the death of the organism and may be uncontrollable. Additionally, the prognosis is poor when more than three body systems are affected by the disease.
Additional questions about blastomycosis in dogs
How is blastomycosis spread?
Blastomycosis is typically spread by inhalation of blastomyces spores from the environment. The fungus is found in soil and organic matter and can affect many animal species. It primarily affects the respiratory system but can involve other organ systems. The fungus is more likely to grow in areas where there are natural water sources, and moist, acidic soils rich in decaying vegetation. Infection occurs when the fungal spores are inhaled. The incubation period in dogs is 5-12 weeks.
How can blastomycosis in dogs be prevented?
There is no vaccine available for blastomycosis, and it is not always possible to prevent exposure to the fungus. However, minimizing exposure to contaminated soil and water sources can help reduce the risk of infection. In areas where blastomycosis is known to occur, it is important to avoid letting your dog dig in the dirt or drink from stagnant water sources.
Can blastomycosis be cured?
In most cases, blastomycosis can be cured with antifungal therapy. Itraconazole is the drug of choice and is effective in the majority of cases. The usual course of therapy is 3-6 months to be effective and curative. Veterinarians will recommend treating for at least 1 month past clinical resolution of symptoms.
What are the long-term effects of blastomycosis in dogs?
The long-term effects of blastomycosis in dogs depend on the severity of the disease. Dogs that are treated early and have no central nervous system involvement typically have a good prognosis and make a full recovery. However, dogs that develop seizures or have more than three body systems affected by the disease often have a poor prognosis.
In conclusion, blastomycosis is a fungal infection that can affect both humans and animals. It is most commonly seen in dogs, although it can affect other animals as well. The main symptoms of blastomycosis in dogs include respiratory problems, eye problems, and fever. A diagnosis of blastomycosis can be difficult, as the symptoms are often nonspecific. The treatment for blastomycosis in dogs includes the use of antifungal drugs. Itraconazole is the drug of choice and is effective in the majority of cases. The prognosis for blastomycosis in dogs is quite good, with reported recovery rates up to 75 percent. If you have any questions about blastomycosis in dogs, please contact your veterinarian for further advice.