Al-Qadisiyah Journal of Veterinary Medicine Sciences

Abstract Histological quantification of lung includes measuring and analyzing the proportions of respiratory area, the respiratory bronchioles which lead to the alveolar sacs and alveoli where gas exchange occurs, and connective tissue quantification, the amount of collagen and elastic fibers, which provide support and elasticity for the lung. This can be done by techniques like image analysis software and histological staining methods, such as Hematoxylin and Eosin, Masson's trichrome and Van Gieson to differentiate connective tissue from air spaces. The present analysis aimed to quantify and compare the respiratory area and connective tissue between two adult, healthy of both sexes independent animal groups cow and sheep based on ten specimens per group (n = 10) were collected from local slaughterhouse in summer (2025). The analysis revealed no significant differences between respiratory area of cow and sheep (P > 0.05), that the average respiratory area in sheep (90.18 µm2) was moderately higher than that in cow (85.21 µm2), indicating a more efficient structure for gas exchange, which associated with higher metabolic demands and active lifestyle of sheep. In contrast, cow lung significantly demonstrated greater amount of connective tissue, suggesting increased structural support necessary for large body size but reduced respiratory efficiency