**5. Gross pathological lesions**

On post-mortem examination of dead pigs from natural outbreaks, the gross pathological lesions may be marked by congestion and petechial haemorrhages on all over the serous membranes. Widespread petechial haemorrhages in the wall of thoracic cavity is the hallmark of the disease. Hydrothorax with presence of strawcoloured fluid in thoracic cavity can be seen (**Figure 1**). All the visceral organs may exhibit petechial to ecchymotic haemorrhages on the serosal surfaces. In some animals, hydrothorax, pleurisy and hydropericardium can also be prominent [18, 19].

The lungs usually show congestions with varying degrees of consolidation and with a marked thickening of the interlobular septa, pleura and rubbery consistency of lungs. There may be petechiae over the lungs (**Figure 2**). In acute cases the lungs may be severely consolidated with liver-like consistency. Whereas, subacute to chronic infection manifest grossly by marbled appearance of lungs (**Figure 3**), rubbery consistency and thickening of pleura (**Figure 4**), and emphysematous changes in lungs [20–22]. Heart may be severely congested and there may be presence of petechial as well as haemorrhagic streaks and necrotic foci which can be visible upon removal of pericardium (**Figure 5**). Rounding of heart and haemorrhages were also observed by Kapoor *et al.* [23]. The liver is one of the severely affected organs in this disease. The lesions may be characterized by congestion, petechiae and multiple necrotic foci on the surface of liver [21, 22]. Splenomegaly is a constant lesion seen in all the cases. There may be haemorrhagic enteritis in pigs died of swine pasteurellosis.

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**Figure 3.**

**Figure 2.**

**6. Histopathological lesions**

*Marbled appearance of lungs of a pig died of swine pasteurellosis.*

Lungs, the primarily affected organ, microscopically shows a variety of lesions from

congestion of capillaries with thickened interlobular septa and atelectasis to severe lesions of perivascular and bronchial infiltration of inflammatory cells. There may be

*Pathological Changes Associated with Natural Outbreak of Swine Pasteurellosis*

*DOI: http://dx.doi.org/10.5772/intechopen.94849*

*Petechiae over lungs of a pig died of swine pasteurellosis.*

*Pathological Changes Associated with Natural Outbreak of Swine Pasteurellosis DOI: http://dx.doi.org/10.5772/intechopen.94849*

**Figure 2.** *Petechiae over lungs of a pig died of swine pasteurellosis.*

**Figure 3.** *Marbled appearance of lungs of a pig died of swine pasteurellosis.*
