Aspergillosis is a fungal disease that occurs after a cat inhales infectious fungal organisms of the genus Aspergillus. Aspergillus is found worldwide in soil and decaying vegetation and affects all mammals, including humans. Though the fungus lives primarily in soil, both indoor and outdoor cats can get aspergillosis, possibly through the accumulation of spores in food or litter. Because this fungal organism exists worldwide, it is impossible to prevent aspergillosis, although most cats exposed to the organism do not get sick. Brachycephalic, or short-nosed, cats, such as Persian or Himalayans, do seem predisposed to developing this disease.

There are two main forms of aspergillosis, sino-nasal and sino-orbital. Sino-nasal aspergillosis occurs when the disease is confined to the nasal and sinus cavities and is the most common form of the disease. Clinical signs of sino-nasal aspergillosis include sneezing, chronic nasal discharge, bleeding from the nose, loud breathing, and sometimes fleshy masses are visible in the nostril. When the disease invades beyond the nose and sinuses into the tissues surrounding the eye, this is known as sino-orbital aspergillosis. A bulging eye, elevation of the third eyelid, or neurologic signs such as blindness or difficulty with balance can be signs of sino-orbital aspergillosis. Very rarely, aspergillosis can become disseminated throughout the body, causing problems such as pneumonia, fever, lethargy, and decreased appetite.

Aspergillosis is diagnosed by visualizing fungal segments, called hyphae, in tissue samples under a microscope. Advanced imaging of the head, such as a CT scan, helps identify the extent of lesions in the nasal cavity, sinuses, and orbital areas but cannot distinguish between aspergillosis and other diseases, such as cancer, without sampling tissue. For sino-nasal aspergillosis, treatment involves combining an extended course of oral antifungal medications and local topical infusion therapy performed under general anesthesia. With sino-orbital aspergillosis, radical surgery may be necessary, but unfortunately, treatments are not always successful. Overall, the prognosis for aspergillosis in cats varies depending on the extent of disease but is improving as techniques for local therapy improve.

Last updated 2021