Vaccination against swine enzootic pneumonia in field conditions: effect on clinical, pathological, zootechnical and economic parameters.

A field study was carried out to evaluate the effect of vaccination against swine enzootic pneumonia in different production systems (closed or one-site, and open, two- or three-site, systems). The percentage of mortality showed statistically significant differences (p < 0.001) in favour of vaccination in all the production systems examined. Zootechnical and economic parameters also reflected the benefits of vaccination, although only the feed conversion ratio showed statistically significant differences (p < 0.030). A macroscopic study of lungs at slaughter pointed to statistically significant differences (p < 0.001) in favour of vaccination in the one- and two-site production systems. The histopathological and immunocytochemical study showed complete concordance with the macroscopic diagnosis (p < 0.001). Such relationship confirms the suitability of macroscopic diagnosis in field conditions.