Blastomycosis in Dogs

(Photo by Cam Bowers)

A Note From Dr. Ed:

This disease is a systemic fungal disease caused by Blastomyces Dermatitidis.  Dogs and people are the most commonly infected species but this organism has been isolated from cats, horses, wolves, ferrets, and polar bears.  This fungus most often appears to be found in the soil, but living near a waterway or water source dramatically increases the chance of becoming infected with Blastomyces.  Although outdoor pets are most often the ones infected with this organism, it can present itself in animals that are 100% indoors.  The truth of the matter is that there are concentrations of this organism throughout various regions in the environment.   If you or your pet happen to stumble across one of these areas, an infection can occur.  At our veterinary hospital we have seen families that have multiple pets infected with Blastomyces.  This is a really serious disease found primarily in the Mississippi, Missouri, and Ohio River Valleys, the mid-Atlantic states, and parts of Canada.

The presentation of an animal with Blastomycosis is extremely variable.  Some dogs will show signs of weight loss, enlarged lymph nodes, increased respiration rate, skin lesions, or fever.  Other pets may simply be lethargic and have minor eye inflammation.  In certain parts of the country, (like here in East Tennessee), we consider Blastomyces a possible diagnosis for every coughing dog.  We also consider it a possible diagnosis for any dog with eye inflammation.  The effectiveness of the treatment for this disease frequently correlates with how quickly a definitive diagnosis can be established.

Although it is great if the organism can be found directly by a cytologic diagnosis (viewing it under a microscope), this is not always possible.  Other diagnostic aids are available, such as the Mira Vista Test, which can be run on a urine sample.  These alternate means of testing have helped improve the possibility of a quick diagnosis.  Remember that the more quickly it is diagnosed, the better the chance of successful treatment.

The treatment for Blastomycosis is a drug called Sporanox (itraconazole).  Sporanox is very effective but unfortunately, it is also very expensive.  If your veterinarian feels that your pet has this disease, don't hesitate to begin treatment.  Luckily, the success rates are great for dogs that get a diagnosis early in the disease process.

Our information is not intended to replace the advice of your veterinarian.  Do not use this information for diagnostic purposes. Always take your pet to your veterinarian to obtain a diagnosis and course of treatment.