Use of Standing Computed Tomography for the Diagnosis of a Primary Respiratory Adenocarcinoma in a Scarlet Macaw (Ara macao)

An adult female scarlet macaw (Ara macao) was referred for evaluation of increased respiratory noise. Previous treatment with antibiotic agents by the referring veterinarian did not improve clinical signs. Upon presentation, when manually restrained, the patient became severely tachypneic with increased respiratory effort. Standing whole-body radiographic images revealed a soft tissue mass at the cranial aspect of the cardiac silhouette, but the origin of the mass could not be ascertained because of superimposed structures. Owing to the birdʼs significant respiratory compromise and concern for risks of general anesthesia, a standing computed tomography (CT) scan was performed without sedation to further assess the origin of the suspected mass. The CT images showed the presence of a large infiltrative intracoelomic soft tissue mass with adjacent keel osteolysis. After attempts at supportive care with nebulization, antibiotic therapy, and antifungal agents, the patientʼs condition declined and was subsequently euthanized. The results of the postmortem examination confirmed a large intracoelomic neoplasm with involvement of the keel, lungs, and adjacent air sacs. The mass was diagnosed as a primary respiratory adenocarcinoma, believed to have originated from the intraosseous air sac epithelium, with local pulmonary, air sac, and intracoelomic metastasis.