Methods of lung lavage in pigs -: a comparison

Lung lavage is a valuable tool for the diagnostic of respiratory diseases in swine, although not all methods are applicable in practice. The impact of three different lavage methods (bronchoscopic, endotracheal, transtracheal) on bacterial and cellular findings as well as on the concentration of the antimicrobial peptide PR-39 was evaluated in 38 healthy pigs. Contamination with ubiquituous microorganisms and the occurrence of pavement epithelial cells were lowest in transtracheal lavage fluid, while the percentage of polymorhonuclear neutrophil granulocytes (PMNs) and the PR-39 concentrations were highest. Cell differentiation was not possible in endotracheal lavage fluid. Diagnostic sensitivity of Mycoplasma hyopneumoniae polymerase chain reaction was highest in combination with bronchoscopic lavage fluid. Isolation of pathogenic organisms was possible in 43% of the pigs and therefore can not be considered as significant for the health status of the herd. In addition, 98 pigs out of different herds suffering from different respiratory diseases were investigated with one of the three methods. A significant positive correlation between concentrations of PR-39 and the relative number of PMNs was found. Aetiological diagnostics were possible in 45% of pigs lavaged endotracheally, in 89% of pigs lavaged bronchoscopically and in 86% of pigs lavaged transtracheally. In conclusion, bronchoscopic lavage fluid can be considered as the most standardized method for scientific investigations, while transtracheal lavage fluid is appropriate for its use in practice for bacteriological and cytological diagnostics.