No simple association between time elapsed from seroconversion until slaughter and the extent of lung lesions in Danish swine

• Published in: Preventive veterinary medicine 2001-12, Vol.52 (2), p.147-161
• Main Authors: Andreasen, Margit, Mousing, Jan, Krogsgaard Thomsen, Lars
• Format: Article
• Language: English
• Subjects: Abattoirs; Actinobacillus Infections - pathology; Actinobacillus Infections - veterinary; Actinobacillus pleuropneumoniae; Actinobacillus pleuropneumoniae - immunology; Actinobacillus pleuropneumoniae - isolation & purification; Actinobacillus pleuropneumoniae - pathogenicity; Animals; Antibodies, Bacterial - analysis; Denmark; Longitudinal Studies; Lung - pathology; Lung Diseases - microbiology; Lung Diseases - veterinary; Lung lesions; Mycoplasma - immunology; Mycoplasma - isolation & purification; Mycoplasma - pathogenicity; Mycoplasma hyopneumoniae; Mycoplasma Infections - immunology; Mycoplasma Infections - veterinary; Pig-microbiological disease; Serologic Tests - veterinary; Swine; Swine Diseases - microbiology; Swine Diseases - pathology; Swine respiratory disease; Time Factors
• ISSN: 0167-5877; 1873-1716
• DOI: 10.1016/S0167-5877(01)00242-2

The association between the extent of pathological lung lesions at slaughter and the time elapsed from seroconversion to slaughter was examined in a longitudinal study including 830 pigs from eight herds. Pigs from an age of 3 weeks were bled every fourth week, and the sera were analyzed for the presence of antibodies to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae serotypes 2, 5, 6, 7 and 12. At slaughter, the extent of mycoplasma-like catharral pneumonia, chronic pleuritis (dorso-caudal and ventro-cranial), interlobular-scar retractions, acute pleuropneumonia and chronic pleuropneumonia was recorded. Poisson regression was used to model the relationship between time elapsed from seroconversion to slaughter (divided into 4-week intervals) and extent of lesions, including “age at slaughter” and “gender” as independent variables and “litter” as an explanatory random variable. Analysis was only performed on lesions which had a prevalence >20% in at least five of the herds (mycoplasma-like catharral pneumonia, ventro-cranial and dorso-caudal pleuritis). Only a few consistent statistical associations were revealed across herds. Pigs seroconverting to M. hyopneumoniae close to slaughter expressed the largest extent of mycoplasma-like catharral pneumonia, and early seroconversion to M. hyopneumoniae was related to large ventro-cranial pleuritic lesions. In these eight herds, recording of the extent of pathological lung lesions at slaughter at most yielded insight into the within-herd epidemiologic dynamics of M. hyopneumoniae — and not to any of the serotypes of A. pleuropneumoniae.