Blastomycosis is a severe systemic infection caused by the fungal organism Blastomyces dermatidis. The organism grows in the soil in specific regions of the country, including the Missouri, Ohio, Tennessee, and Mississippi River valleys. Dogs and humans are most at risk for infection; however, cats, horses, and other animals are occasionally affected.
Because many tissues can be infected by the organism, the signs of the disease will vary. Signs such as difficulty breathing, exercise intolerance, weight loss, and coughing will be seen when pneumonia, a common manifestation of respiratory infection, is present. With bone infections, lameness may be the only sign. A third of the cases involve the eyes, resulting in pain, redness, glaucoma, retinal detachment, and blindness. In addition, about one-fourth of affected animals will have skin disease that may manifest as nodular areas or draining wounds. The prostate and testes can also be affected. Prostatic involvement may result in abdominal pain, a stiff gait, and difficulty urinating. Testicular infections may result in swelling, pain, and sterility.
Systemic fungal infections are always serious, and can be difficult to treat. Many times affected animals are immunocompromised, or have weakened immune systems, making the disease harder to eradicate. If untreated, most infections are eventually fatal.
