Inflammation involving the nasal passages of dogs and cats is termed rhinitis. The hallmark clinical signs seen with a case of rhinitis include sneezing and nasal discharge. Causes of rhinitis include bacterial infections, nasal tumors, trauma, and foreign bodies.
In addition, the fungal organism Aspergillus fumigatus can invade the bones and tissues constituting the nasal passages in dogs and cats, resulting in rhinitis. The fungal organism Cryptococcus neoformans infects cats in the same way.
The nasal discharges associated with fungal disease, which are usually green and thick in nature, might persist for months at a time. In addition, ulceration involving the outer surface of the nose is sometimes seen.
Aspergillosis can occur primarily on its own or secondarily to other conditions that might compromise the immune system.