title: No simple association between time elapsed from seroconversion until slaughter and the extent of lung lesions in Danish swine.
abstract: 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.
authors.affiliation: Danish Bacon and Meat Council, Veterinary and Food Advisory Service, Axelborg, Axeltorv 3, DK-1609 Copenhagen V, Denmark. man@svs.dk
authors.forename: M
authors.initials: M
authors.lastname: Andreasen
authors.forename: J
authors.initials: J
authors.lastname: Mousing
authors.forename: L
authors.initials: L
authors.lastname: Krogsgaard Thomsen
mesh_terms: D000003:Abattoirs; D000189:Actinobacillus Infections / Q000473:pathology / Q000662:veterinary*; D016977:Actinobacillus pleuropneumoniae / Q000276:immunology / Q000302:isolation & purification* / Q000472:pathogenicity; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D008137:Longitudinal Studies; D008168:Lung / Q000473:pathology*; D008171:Lung Diseases / Q000382:microbiology / Q000662:veterinary*; D009174:Mycoplasma / Q000276:immunology / Q000302:isolation & purification* / Q000472:pathogenicity; D009175:Mycoplasma Infections / Q000276:immunology / Q000662:veterinary*; D012698:Serologic Tests / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000473:pathology; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial