PATHOMORPHOLOGICAL CHANGES AND BACTERIAL PATHOGENS ASSOCIATED WITH SWINE PNEUMONIAS IN SOUTHWEST NIGERIA

Pneumonia is a major economic threat to swine industry worldwide, however, there is still dearth of information on the pathology and associated pathogens in Nigeria, and these were therefore investigated. Lungs from 408 slaughtered pigs were randomly collected from abattoirs in Abeokuta, Ibadan and Lagos. The lung samples were cultured for bacterial pathogens using standard techniques, while formalin-fixed tissues were processed for histopathological examination. Grossly, the most consistent lesion was bronchopneumonia (35.3%). The main histopathological findings were lymphoid hyperplasia of bronchus-associated lymphoid tissue (BALT) (88.2%), suppurative bronchopneumonia (63.6%), suppurative bronchitis and bronchiolitis with concurrent epithelial hyperplasia (57.1%), as well as thickened alveolar septa due to cellular infiltration consisting predominantly of neutrophils (54.1%). Ten different species of bacteria were isolated from the lung samples in which two or more pathogens were isolated from each sample (82.7%). Pasteurella multocida was the most frequently isolated bacterium (54.8%). Among the bacteria isolated, there were significant (P < 0.05) differences in the frequencies of isolation of β-haemolytic Streptococci, P. multocida, Haemophilus species and Escherichia coli between the pneumonic lungs and apparently normal lungs. The results of bacterial culture, gross and histopathological changes recorded in this study are consistent with bacterial pneumonia possibly caused by most of the bacteria identified in the present study.