Relationship between tail lesions and lung health in slaughter pigs.

Tail lesions are associated with poor health either because they serve as a point of entry for pathogens or because of shared risk factors. This study investigated the relationship between carcass tail lesion and lung lesion severity scores in slaughter pigs. Carcasses were scored after scalding/dehairing for tail lesion severity (0-4). Lungs were scored according to an adapted version of the BPEX pig health scheme. Severity of enzootic pneumonia (EP-like lesions) was recorded on a scale of 0-50. Severity of pleurisy was scored on a 0-2 scale with score 2 equating to severe pleurisy or those lungs that remained attached to the chest wall ('lungs in chest'). The database for assessing pleurisy lesions contained all pleurisy scores (n=5628). Lungs with a score of 2 for pleurisy were excluded from the analysis of all other lung lesions as such lungs could not be assessed for other lesions (n=4491). Associations between tail lesions and different lung lesion outcomes were analysed using generalized linear mixed models (PROC GLIMMIX) with random effect for batch. Males were more affected by moderate (OR=1.9, 95% CI 1.51-2.34) and severe (OR=5.8, 95% CI 3.45-9.70) tail lesions than females. EP-like lesions and pleurisy were most commonly observed. Pigs with severe tail lesions tended to have more 'lungs in chest' than pigs with moderate tail lesions (P=0.1). No other associations between tail lesions and lung lesions were found. Males had higher odds of having EP-like lesions (OR=1.2, 95% CI 1.05-1.36) than females. Tail lesions on the carcass may not be an accurate predictor of lung health. However, tail lesions are important welfare indicators and respiratory disease is a significant infectious condition affecting pigs. Thus, recording of tail and lung lesions at meat inspection provides valuable information regarding on-farm health and welfare of pigs.