“…All these changes in pulmonary histophysiology may be associated with the gradual decrease in NPV values that was observed between 120 and 24 h before whelping in the present study; the terminal stages of growth and secretory activity of connective tissue ducts appear to be inversely related to pixel intensity of the tissue (Giffin et al, 2009(Giffin et al, , 2014. Similarly, an increase in NPVs just prior to parturition may be associated with the saccular phase of foetal lung development (Lourenço and Machado, 2013), reflecting the biochemical and functional adaptations that occur during lung maturation (Benson et al, 1983;Nicholas et al, 1986;Adler et al, 1990), specifically, the reduction in total protein content (Ahmadi et al, 2013) and augmentation of enzymatic activity (VanDuzer et al, 2014). Results of the present study, however, are inconsistent with those reported by Banzato et al (2017), where there was an abrupt increase in pulmonary echogenicity during the canalicular phase and a plateau during the saccular phase of foetal lung development in various large dog breeds.…”