Blastomyces dermatididis is a fungal organism that causes Blastomycosis, a fungal infection in dogs. The fungi is found in sandy, acidic soil in close proximity to water. It can cause severe respiratory problems and may lead to blindness. The first symptom of this disease is the appearance of crusty sores on the skin.

Blastomycosis is a serious systemic fungal disease that primarily infects dogs as well as people and can cause respiratory, eye, and skin lesions. It can be fatal if not diagnosed and treated quickly. Even with proper treatment many dogs do not recover from the infection.

The disease is usually found only in the area of the Mississippi, Missouri, and Ohio River valleys, the Mid-Atlantic States and parts of Quebec, Manitoba, and Ontario.

A blastomycosis fungal infection in dogs happens when the animal inhales the blastomycosis spores found in the soil. The spores then travel down into the airways of the lungs and an infection develops. Once it infects the dog’s lungs it spreads throughout the body to the skin, eyes, bones, lymph nodes, subcutaneous tissue, and brain.

The symptoms of blastomycosis include lack of appetite, fever, depression, weight loss, coughing, eye problems, lameness, or skin problems. These symptoms may be present for a few days or a few weeks.

Approximately 85% of dogs who have blastomycosis also have lung lesions and 40% have eye lesions. Skin lesions are found in 20% to 40% of infected dogs.

The most common treatment for this disease is oral administration of the antifungal drug Itraconazole. This drug needs to be given to a dog every day for 60 to 90 days. It is the safest and most effective way to treat the disease, but the drug was meant for humans and is very expensive. An injectable drug, Amphotericin B, is also prescribed by some vets, and must be given intravenously several times a week by the veterinarian.

There is currently no vaccine available to protect against blastomycosis.

Histoplasmosis is a fungus found in dust that causes infection in dogs under four years of age. The result is a swelling of the lymphatic nodes in the neck and armpits. The fungus is found in the soil and enters the body through a dog’s lungs, causing a range of respiratory and intestinal symptoms. Some animals are able to recover from the infection without any medication while others require treatment with an antifungal medication.

Infections are more common in dogs who live outside or spend a good amount of time wandering around forested areas. Dogs become infected by inhaling the spore-like particles of the fungus present in the soil. The symptoms are varied and depend on the severity of the infection. Many healthy dogs recover from minor respiratory infections on their own. Dogs with a weak immune system may develop a more severe infection that can spread to its intestinal system, lymph nodes, spleen, liver, or even the eyes.

The most common symptoms are weight loss, fever, and loss of appetite. A dog may also have a cough and experience difficulty in breathing. X-rays of the chest and abdomen are usually necessary to detect the organisms in infected tissue. A biopsy of infected tissue may be done because the tissues often contain some of the small fungal organisms.

In simple cases of the respiratory form of histoplasmosis, treatment may not be necessary because the dog will often clear the infection on its own. However, the risk of the infection spreading or becoming more severe is very real.