Blastomycosis In Dogs

Blastomycosis is a relatively rare disease cause by the fungus Blastomyces dermatitidis.  It is most commonly found around river banks and other wet places.  Hunting dogs are the most common victims of this disease.  It is spread when a dog inhales the spores or receives a puncture wound that contains the spore and introduces it into the body.  The spores then begin to grow in the lungs and can suffocate the dog by clogging up the lungs.  It can also spread into other areas of the body such as the eyes, joints, and other organs.  If left untreated, the disease results in death.

Symptoms to look for include fever, flu-like symptoms or pneumonia, lost of appetite, weight loss, eye infection, sudden blindness, difficulty breathing, skin sores or lesions that will not heal, decreased stamina, joint pain, reluctance to walk and loss of coordination, and lymph gland swelling.

It is often necessary to be persistent with your veterinarian to diagnose blastomycosis because it is rare.  Many other things can cause one or more of these symptoms.  It often takes several weeks to make the correct diagnosis.  It may be necessary to go to a specialist to definitively determine what is wrong.  Be sure to let your vet know if you have traveled recently to a river system and gone hunting with your dog or let him run there.

This disease is diagnosed in several ways.  Specifically, tests are run for a fungal infection using any of the following methods:  analysis of fluid drained from skin lesions, sputum culture, tracheal wash, chest x-rays, blood and urine analysis, examination of the cells in the lymph nodes, examination of lung tissue.  Tissue samples may be taken to test for the presence of fungal organisms if none of these are available.

Blastomycosis is treated with anti-fungal medication.  It is challenging and frustrating to treat as it may take a year or more of therapy to eradicate the fungus.  It also may only go into remission, only to pop out again when the dog is stressed or has immune system problems.  In addition, the medications are expensive and dangerous.  They can cause organ damage in and of themselves.  It is very like giving chemotherapy for cancer — the aim is to kill the fungus without killing the patient.

The most common drugs used to treat blastomycosis are itraconazole, amphotereicin-b, itraconazole suspension, ketoconazole, fluconazole, posaconazole, voriconazole, and prednisone.

When treatment starts, dogs seem to get worse for five to eight days.  This is probably because the yeast is dying and the body must reabsorb it and rid the body of it.  After this, the dog should start to get better.

The usual first line drug is itraconazole.  Amphotereicin-b is used in life threatening infections, although it can damage the kidneys.  Actually, all of these drugs are very hard on the kidneys.

There is no vaccine or preventative for blastomycosis.  The best thing you can do is limit the amount of time your dog spends in areas where the fungus is present.  This may not be practical if you live in one of those areas.  In that case, simply be alert to the symptoms and visit the veterinarian at the first sign of them.