A retrospective study using condemnation data of market hogs in Ontario for quantitative disease surveillance

A longitudinal study was conducted to investigate whether Ontario provincial abattoirs are a useful source of information for syndromic disease surveillance of finisher hogs. Multivariable negative binomial models were applied to examine relationships among non-disease factors and whole and partial carcass condemnations. Scan statistics were employed to detect clustering of whole carcass and partial carcass condemnations related to lungs and kidneys. Associations between higher condemnation rates and larger abattoir processing capacity were consistent for all models, while interactions between region and year demonstrated different trends between the models. Whole hog carcass condemnation data performed better than partial carcass condemnation data at detecting high rate clusters consistent with a documented porcine circovirus-associated disease outbreak. Improvements in the reporting of partial carcass condemnation data and consideration of non-disease factors such as abattoir size and region are required if these data are incorporated into a syndromic surveillance system for Ontario swine.