Computed Tomographic Characteristics of Normal Lungs in Blue and Yellow Macaws (Ara ararauna)

Respiratory disease is common in psittacine birds; thus, having evidence-based methods to evaluate clinical cases is important for confirming a diagnosis. The purpose of this study was to describe the computed tomographic characteristics of the normal lung parenchyma of wild blue and yellow macaws (Ara ararauna), including measuring lung volume and normal radiographic attenuation of the lung parenchyma. Ten blue and yellow macaws from a wildlife center were used for this study. For computed tomography, transverse 1-mm slices were obtained, as well as multiplanar and 3-dimensional reconstructions for description of tomographic anatomy. Quantitative lung radiodensity was evaluated by regions of interest and via the histogram method. The lungs occupied the dorsal region of the coelomic cavity, with a triangular appearance on sagittal view, and were divided into left and right lungs. The lungs showed no lobulation. Mean attenuation values obtained were -727.19 ± 44.53 Hounsfield units by the histogram method and -722.19 ± 29.69 Hounsfield units by regions of interest. There was no significant difference (P > 0.05) between methods. Mean lung volume was 26 ± 6.03 cm³. The description of the normal computed tomography lung anatomy and density values of blue and yellow macaws are useful baseline data that can be applied to the diagnosis of respiratory diseases in this species.