Coccidioidomycosis and Blastomycosis

Canine fungal diseases include coccidioidomycosis and blastomycosis. Commonly mistaken for lung cancer, these diseases come from the environment. Fungal soil organisms create airborne microscopic spores, which easily pass deep into the dog's lungs. Healthy dogs' immune systems usually fight these diseases, but high numbers of spores or an immune-compromised animal allow rapid spore reproduction and signs of disease.

  1. Blastomycosis Infection

    • Blastomycosis is present in soil along streams, lakes and ponds. It is common in the upper Midwest United States following the Mississippi and Ohio rivers. Sometimes it lives in landscaping and potting soils. Dogs acquire the disease by inhalation of spores while digging and probing for scents within organic soil. Upon entering the lungs, spores transform into yeast which has the ability to disseminate to other sites of the body such as skin, eyes and joints.

    Coccidioidomycosis Infection

    • Coccidioidmycosis occurs in semi-arid regions of the southwestern United States. Infection occurs from inhalation of spore-covered dust particles. Valley Fever is the common name for this disease. Once inhaled the spores grow into spherules, which enlarge until they rupture. Rupturing releases hundreds of new spores, spreading the infection. Most dog immune systems kill the spherules, but in compromised animals it becomes a serious disease.

    Symptoms and Diagnostics

    • Common signs of both fungal infections include fever, depression, weight loss and coughing. Untreated progressive signs can be as serious as blindness, lameness, seizures and respiratory distress. Diagnosis is problematic because symptoms mimic many other diseases. X-rays commonly lead to a misdiagnosis of lung cancer. A complete history of a dog̵7;s activities and travels are imperative to a correct diagnosis. Blood tests can screen for exposure, but only microscopic identification of the organism proves disease.

    Treatment

    • Treatments for these diseases depend on how far the disease has progressed. If the fungus is only in the lungs and has not progressed systemically to nerves, joints or other tissues, prognosis is good. A dog in poor condition may react poorly to antifungal therapy, specifically when large numbers of spores die quickly and cause severe inflammatory reactions. New antifungal agents, such as itraconazole, are well-tolerated and have few side effects.

    Complications

    • Approximately 20 percent of animals surviving treatment have recurrence. Relapses usually occur within the first six months after treatment. Antifungal drugs may damage liver and kidneys during treatment, therefore clinical monitoring is essential. Fungal infection spread to joints causes inflammatory pain. In eyes it causes blindness and nerve damage leads to immobility. Unfortunately, symptom variability can lead to a delayed diagnosis and increased complications.