Bronchoscopic, endotracheal and transtracheal lung lavage were evaluated in 38 healthy pigs taken from a nucleus herd in a good state of health with respect to their applicability in practice and the traceability of bacteria, cellular parameters and the antimicrobial peptide PR-39 in the respective lavage fluid samples. The total cell count, qualitative morphological cellular characteristics as well as PR-39 could be determined in all lavage fluid samples, while quantitative cell differentiation was not possible in endotracheal lavage samples. The comparison of the three methods resulted in a higher proportion of polymorphonuclear neutrophil granulocytes (PMNs) and higher concentrations of PR-39 in transtracheal samples. For this reason different valuation standards with respect to PMNs and PR-39 concentrations are presupposed for transtracheal lavage samples. The occurrence of pavement epithelial cells as well as the number of contaminating bacterial species per sample was the lowest in transtracheal lavage. Mycoplasma hyopneumoniae polymerase chain reaction appeared to have the highest diagnostic sensitivity in combination with bronchoscopic lavage. In conclusion, bronchoscopic and transtracheal lavage were considered to be more appropriate for bacteriological and cytological diagnostics than endotracheal lavage.

In bronchoalveolar lavage fluid (BALF) of pigs originating from different herds bacteria, cells and the antibacterial peptide PR-39 were examined to gain information about the lung health status. In a high health nucleus herd 56% and in low health herds 20-100% of the examined pigs were found positive for potentially pathogenic bacteria. Based on these findings, a novel definition for bacterial respiratory tract disease was established using an 8% cut-off for the relative number of neutrophils in bronchoscopic and a 40% cut-off in transtracheal BALF in combination with the occurrence of potentially pathogenic microorganisms. The antibacterial peptide PR-39 was highly correlated to this definition of respiratory disease. An assessment of the bacteriological respiratory health status appears to be possibly based on the determination of PR-39 concentrations in BALF using different cut-off values according to the lavage method (2.5 nM for bronchoscopic and 5 nM for transtracheal BALF).