Histopathologic evaluation of the lungs confirmed the progressive nature of the pulmonary lesions and corroborated the radiologic data. Suppurative and necrosuppurative bronchiolitis seen on days 1 and 2 became progressively worse by days 3 and 7 post-infection. The inflammation tended to be patchy or multifocal and an entire lung lobe was never uniformly affected, corresponding to the multiple patchy lesions seen on PET/CT by the end of the study. This also agreed with the analyses of the viral titers in various sections of the right caudal lobe and the PET/CT imaging. Our analyses of viral titers in the four representative sections suggest different levels of infiltration of the lobe. The histopathologic scoring for bronchiolitis correlated the best with the SUVMax of the lesions seen in the right and left lungs on PET.