Most Common Canine Illnesses – Blastomycosis


As far as infectious diseases go, so far we have covered mostly viral infections and the conditions that different viruses cause here on DogShow. Today, we are going in a different direction with a fungal infection called blastomycosis. The condition is caused by an organism called Blastomyces dermatitidis which is endemic to certain parts of North America (meaning that it does not appear elsewhere in the world, although this has somewhat changed as of lately). The condition is also known as North American blastomycosis and Gilchrist’s disease.

The fungus that causes the infection is usually found in sandy areas around large rivers where it feeds on decomposing trees and other flora. In the United States, it is most often found in the Mississippi River Valley, the Great Lakes Basin, central Appalachian Mountains and St. Lawrence River Valley. It is important to point out that other parts of the country also report cases of blastomycosis, although to a much lesser extent. The condition is mostly diagnosed in dogs and people.

The infection starts with the dog inhaling spores that are found in contaminated soil. The body temperature is perfect for the spores to transform into a yeast which initially infects the lungs. Via lymph and blood, the infection can spread to other body systems and tissues. In dogs, the tissues that are most commonly affected include lungs, eyes, skin, bone and lymph nodes.

The most common symptoms are those indicating that the lungs have been infected. These include harsh dry sounds coming from the lungs and cough. In addition to this, the dog will get winded sooner and their capacity for exercise will diminish. It is crucial to examine the dog radiographically to ensure that the infection has not caused lung lesions which can lead to severe complications and even respiratory failure.

Budding yeasts in cytoplasm of giant cells at arrows. Broad-based budding and double countoured cell wall seen in the giant cell in the center is characteristic of Blastomyces dermatiditis.

Budding yeasts in cytoplasm of giant cells at arrows. Broad-based budding and double countoured cell wall seen in the giant cell in the center is characteristic of Blastomyces dermatiditis.

In between 30 and 50 percent of dogs suffering from blastomycosis, lymph nodes will become inflamed or enlarged. Furthermore, between 20 and 50 percent of dogs will also experience the infection of the eyes. It is essential to address these infections as soon as possible in order to preserve vision. Eyes can be seriously damaged by blastomycosis and rapid response is crucial.

The skin may also become infected, causing lesions that can be ulcerated, although not necessarily. The parts of the body where lesions appear usually include nail beds, face and the snout. If your dog is diagnosed with blastomycosis, you should inspect their skin immediately. Bone can also be affected by blastomycosis and in some cases it can lead to more or less pronounced lameness. About a third of infected dogs experience bone infections.

While there are many fungal infections that can be effectively destroyed by the dogs’ immune systems, blastomycosis is not one of them. In short, some sort of treatment will be necessary in order to cure the infection and save the dog. By far the most common treatment is with an antifungal drug called itraconazole. The treatment is a long one, lasting from 60 to 90 days and it needs to be completed in order to ensure that the infection will not return. Dogs that are intolerant to itraconazole will be treated with other, similar medications.

Another thing that is very important to point out is that this condition usually causes severe appetite loss. Because of this, you might need to encourage your dog to eat or even force feed it during the early days of the infection.

Blastomycosis cannot be transferred from the infected dog to a healthy one. The only way to contract the disease is through inhaling the spores. Unfortunately, it is near impossible to ensure that your dog will not get the condition, especially if they spend a lot of time in the nature, near rivers and stagnant waters. The best thing you can do is familiarize yourself with the symptoms, know how to recognize them and visit the vet as soon as you notice any of them.


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