Macroscopic photographs of the entire lung from dorsal and ventral views, and microscopic photographs of lung histopathology. In general, alveolar consolidation and hemorrhage appeared substantially more in dorsal areas of the lower lobes (dependent zones). Lung samples that underwent high-frequency oscillatory ventilation (HFOV)-9 Hz showed significant improvement than those ventilated at 3 Hz. Also, lung histopathology revealed more alveolar and interstitial hemorrhage, atelectasis, alveolar and interstitial neutrophil infiltration, interstitial lymphocyte infiltration, and hyaline membrane formation in the HFOV-3 Hz and conventional mechanical ventilation (CMV) groups. Histological samples were stained with hematoxylin and eosin, magnification at 10 × 10.