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Blastomycosis in Dogs

Blastomycosis is a fungal infection.

Blastomycosis is a fungal infection caused by Blastomyces dermatitidis.

Cause of Blastomycosis in Dogs

The cause of blastomycosis infection is inhaling the infective fungal spores, which are common in wet areas like swamps, riverbanks, and lake areas. Once in the body, the fungus affects the lungs, resulting in fungal pneumonia. The immune system tries to mount a defense, but the result is even more inflammation that irritates the body.

Blastomycosis can result in organ failure, including respiratory arrest, and death.

Signs of Canine Blastomycosis

Signs that a dog has contracted blastomycosis include:

  • Weight loss
  • Decreased appetite
  • Cough and labored breathing
  • Red eyes and discharge from the eyes
  • Limping (due to inflammation of the lining of the bones)
  • Skin sores that drain
  • High fever
  • Enlarged lymph nodes
  • Enlarged testicles and prostate in male dogs
  • Seizures

Diagnosis of Blastomycosis in Dogs

When a dog has some or all of the signs of blastomycosis along with a history of having been out hunting or in a swamp or lake, the veterinarian may suspect the condition. The doctor will need to rule out other causes of such signs, including pneumonia, cancer, heart failure, and a host of different skin, joint, and lung conditions.

Inflammation will be evident on blood results, and some dogs will have a high calcium value when they have blastomycosis. Fine needle aspirate of the lymph nodes, a transtracheal wash, or impression smears of sores on the skin that are draining may reveal blastomycosis organisms under the microscope. Special stains used on the microscope slides can help make the organisms easier to see.

Treatment of Canine Blastomycosis

Dogs with blastomycosis are treated with itraconazole or fluconazole, which are anti-fungal medications. Severely affected dogs may need hospitalization and oxygen therapy. Treatment is necessary for a minimum of 60 days and sometimes much longer.

X-rays can be taken of the lungs at intervals to monitor the infection's response to treatment. Often, the lung fields look worse early in the treatment as the organisms begin to die, and even more inflammation occurs. The dog's clinical signs may get worse then too, so the dog's cough and breathing should be monitored especially closely during the first few days of therapy.

Prognosis for Canine Blastomycosis

The prognosis for dogs with this condition is guarded. About a quarter of dogs die within the first week or so of treatment. The earlier the condition is recognized, properly diagnosed, and treatment is begun, the better the chance of survival. The medications can also have adverse side effects that can be severe in some dogs.

Is Blastomycosis Zoonotic?

Blastomycosis isn't directly transferrable from dogs to humans except through bite wounds. However, people can inhale the spores from the same source as their dog.

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