Diagnostic Laboratories ----------------------- Subclinical illness in caged birds makes diagnosis of disease difficult. Consequently, the avian veterinarian must rely heavily on diagnostic laboratories to provide tests that can aid in the diagnosis and treatment of disease, as well as help monitor the clinical course of the avian patient. Bacterial and fungal diseases can be diagnosed in the microbiology laboratory, and the proper and most effective antimicrobial drugs (antibiotics, etc.) to use in treating these diseases can be determined.