FIG. 1.

Canine lung sections. (A) Typical fibrino-suppurative, necrotizing, and hemorrhagic pneumonia due to S. equi subsp. zooepidemicus, characterized by diffuse filling and obliteration of alveolar spaces by numerous neutrophils, fibrin, and proteinaceous fluid. Bronchioles contain hemorrhaged blood, proteinaceous fluid, and sloughed necrotic cells. This section was stained with hematoxylin and eosin. Magnification, ×20. (B) Neutrophils frequently contain numerous intracellular Gram-positive cocci. This section was Gram stained. Magnification, ×40.