Pathological investigation of an outbreak of pneumonic pasteurellosis in pigs

An outbreak of pneumonic pasteurellosis in swine was studied in an organized farm in Bareilly. The affected animals developed symptoms marked by fever, lethargy, respiratory distress, erythema, marked oedema and cyanosis of the skin. The affected animals died within 4–7 days after the onset of clinical symptoms. Necropsy examination showed congestion of lungs, liver, kidney, nasal turbinate and lymph node, frothy exudate in trachea and bronchi, consolidation of apical lobes in lungs and petechial haemorhages over serosal surface of intestine, epicardium and endocardium. Histopathology revealed fibrinous pleuritis, fibrino- suppurative bronchopneumonia with bacterial colonies in lungs, necrotic changes and haemorrhages in renal parenchyma, haemorrhages and infiltration of mononuclear cells in the liver. Impression smears from spleen stained with Giemsa's stain exhibited bunches of bipolar cocco-bacilli. In bacteriological examination, pure bacterial colonies were isolated on blood agar from lungs and spleen of affected pigs. Culture characteristics, colony PCR from the cultures, sequencing of purified PCR product identified the isolated causal bacteria as Pasteurella multocida.