This is a skin and subcutaneous infection acquired by contact with spores in the soil. The spores gain access through puncture wounds caused by thorns and splinters; therefore, the disease is seen most often in hunting dogs. Most cases are reported in the northern and central portions of the United States, especially along coastal areas and river valleys.
A nodular, draining, crusted sore forms at the site of the skin wound, usu- ally on the trunk or head. There may be several small firm nodules in the lymph glands that form a chain beneath the skin. On rare occasion the dis- ease becomes systemic and spreads to the liver and lungs. The outlook for these dogs is guarded.
The diagnosis is made by removing a piece of tissue and examining it under the microscope; or more conclusively, by growing the fungus in culture. A fluorescent antibody test can be performed on infected tissue or serum.
Treatment: Response is excellent when the infection is limited to the skin and surrounding tissues. Potassium iodide (a saturated solution) has been used, but care must be taken due to possible toxicity. Antifungals of the imidazole group (as described for Histoplasmosis) are therefore the agents of choice. Treatment needs to be continued for a month after clinical signs are resolved.
Public health considerations: Sporotrichosis is known to infect humans handling animals with infective drainage. It is important to wear rubber gloves and take strict hygienic precautions when handling all animals with draining wounds.