A 7-year-old, spayed female Chihuahua with dyspnea, intermittent cyanosis, and dermal plaques was diagnosed withhyperadrenocorticism. Thoracic radiographs showed markedly hyperdense alveoli in multiple lung lobes. Computed tomography(CT) images showed lung mineralization confined to the lung parenchyma and pituitary macroadenoma. Pulmonary mineralizationsecondary to hyperadrenocorticism is commonly found on histopathologic examination. However, those lesions are rarely identifiedradiographically. We describe obvious pulmonary mineralization secondary to hyperadrenocorticism found on radiographs andpresent the first report regarding CT imaging of the mineralization. Pulmonary mineralization should be considered when a dogaffected by hyperadrenocorticism shows diffuse lung mineralization on radiographs.