Fig. 2.

Microscopic lesions of the lungs from pigs infected with: (a) B. bronchiseptica only, showing mild areas of interstitial thickening of the alveoli with mononuclear cells; (b) PRCV only, showing areas of moderate interstitial thickening of alveoli with mononuclear cells or (c and d) coinfected with both B. bronchiseptica and PRCV, showing areas of severe interstitial thickening of the alveoli with mononuclear cells, lymphocytic perivascular and peribronchiolar cuffing, and accumulations of neutrophils in the bronchioles (c); intra-alveolar aggregates of neutrophils, macrophages, epithelial cells, and necrotic debris (d). Sections are from the lungs of pigs shown in Fig. 1.