In budgerigars, a relative monocytosis and basophilia may be the only abnormal hematologic finding, suggesting chlamydiosis. The hemogram of aspergillosis and tuberculosis may be similar and includes leukocytosis and monocytosis. The stage of infection and host response in patients infected with Aspergillus or mycobacteria may result in little or no hematologic changes. Monocytopenia is not documented, but a low or zero monocyte count is normal for most species. Morphologic changes can include visualization of intracellular bacteria in septicemic birds.
Monocytes can become macrophagic in appearance in some serious chronic infections.