Histoplasmosis is a disease of people and animals caused by a fungus called Histoplasma capsulatum. This fungus can exist in two forms (dimorphism). One form is a mold phase capable of floating in air, and the second form is a yeast phase that is capable of surviving and multiplying in body tissue. It is as common in dogs as in cats. Although they may show similar signs, cats most often show signs of breathing difficulty, whereas dogs usually show intestinal disorders accompanied by diarrhea.
Animals contract histoplasmosis by breathing the mold into their lungs (primary pulmonary stage). The organisms remain in the lungs until destroyed by body defenses and treatment or until they overwhelm the body. From the lungs, the disease may spread (disseminated stage) to any other tissue, such as the bones, kidneys, liver, spleen, lymph nodes, and eyes via the blood and lymph system. It may cause fever, anemia, depression, and weight loss. Animals with the disseminated form have little or no chance of surviving. However, if the disease remains in the primary pulmonary stage, your pet has a better chance of surviving, depending on its individual resistance and state of health.
People cannot contract histoplasmosis by direct contact with infected pets.
Important Points in Treatment
1. Diagnostic tests, including complete blood counts, serum chemistry profiles, cultures, cytology, and radiographs (x-rays), provide an overview of your pet’s organ systems and general physical condition. It is important for some tests to be repeated at certain intervals to help guide your pet’s therapy.
2. Treatment may extend for several weeks.