Abstract
Microbiological and histopathological examinations were carried out on five dead cockatiels ranging in age from one to two months，while oral swabs were taken from four live cockatiels with cockatiel lockjaw syndrome. Multiple bacterial agents were isolated from the lungs and from swabs of the nasal passage and oral cavity. Bordetella avium was isolated from five of the nine cockatiels. All isolates possessed a dermonecrotic toxin gene，which is thought to be responsible for pathogenicity. Histologically，skeletal muscles within the temporomandibular region showed denaturation and necrosis. Necrotic muscle fibers were organized by proliferated fibroblasts. Moderate to severe infiltrations of inflammatory cells and clusters of bacteria were observed. The antimicrobial susceptibility of B. avium isolates was investigated. The isolates were highly sensitive to common veterinary antibiotics such as beta-lactams，aminoglycosides and tetracyclines.
