Categories: Diseases & Conditions

Blastomycosis: Symptoms and Treatment in Dogs

Blastomycosis, called blasto for short, is caused by fungus blastomyces dermatitidis. Simply put, blastomycosis is a very serious and potentially deadly illness that’s caused by a fungus typically found in the soil near water ways or swampy areas. The spore that causes the infection is airborne, so soil that has been disturbed or dug up is most likely the source of airborne spores. Once inhaled, the spores turn into a yeast that rapidly infests the lungs.

Because blastomycosis can have multiple symptoms, it’s unlikely to be quickly diagnosed unless you or your veterinarian are already aware blasto is in your area. As a result, the illness has usually progressed beyond the point of treatment and recovery by the time other illnesses or disease are ruled out and blastomycosis is diagnosed. Blasto is not communicable from dog to dog, or dog to human, although humans, cats, and other mammals can become sick if they inhale the spores.

Blasto can affect virtually every system in a dog’s body, so observation and a physical exam, including blood tests, are unlikely to point a veterinarian in the direction of a blastomycosis diagnosis. Three dogs recently stricken in southwest Minnesota exhibited an array of symptoms: swollen muzzle, significant and very quick weight loss, seizures, raspy breath, trouble breathing, swollen lymph nodes, lethargy, fever, chills, depression, and sores that wouldn’t heal. It wasn’t until the veterinarian did a microscopic examination of a scraping from the unhealed sore on one of the dogs that the yeast cells were discovered, making the blasto diagnosis possible. In speaking with a local veterinarian, I’m aware of other dogs in Minnesota whose eyes and eyesight were affected and who experienced paralysis in their hind legs. Blastomycosis is also suspected to have been the cause of some dogs who exhibited pneumonia-like respiration, skin lesions, testicular enlargement, and bleeding gums.

Once diagnosed, blasto is most often treated with Itraconzole, an antifungal agent. Even then, symptoms of blastomycosis can get worse before they get better if there are massive amounts of dead yeast in the dog’s system that the body must expel. Treatment of blasto usually lasts several months, and you can expect costs to run into the thousands of dollars. The good news is that the vets I’ve spoken with believe that if blasto is caught early, before it can spread too far, most dogs can be effectively treated. The key is early detection, and that usually happens only if you or your vet keep blasto in the backs of your minds when presented with a sick dog.

To date, there are no known blastomycosis preventative medicines or vaccines. If your dog does become sick, let your veterinarian know if you suspect blasto. Being aware of any cases in your area, knowing symptoms to look for, and being proactive if your dog should fall ill is the best approach. Blastomycosis is not a reported disease, so information on the numbers and frequency of cases is limited; this also adds to delays in diagnosing blasto.

There is also an excellent forum for anyone wanting more information — or to share information — about blastomycosis: http://blastomycosis.ca/forum/