Undocked Tails, Mycoplasma-like Lesions and Gastric Ulcers in Slaughtering Pigs: What Connection?

SIMPLE SUMMARY: Many factors contribute to the welfare and health of animals in commercial production systems and, if not well managed, might contribute to the onset of abnormal behaviors such as tail biting on pig farms. This is an expensive and welfare-decreasing complication in the current modern swine industry that might be particularly challenging in farms rearing undocked pigs. Legal and market-driven requirements of pork production from undocked pigs are increasing the percentage of animals with long tails and consequences should be evaluated. The aim of the present work was to monitor tail, pluck (lungs, pleurae, and liver), stomach, carcass, and thigh lesions in slaughtering pigs belonging either to conventional docked batches or to batches from farms with the complete ban on tail docking. Results showed a higher prevalence of tail lesions on undocked batches, suggesting that more and alternative efforts to manage long-tailed animals are needed. Moreover, undocked batches showed higher frequencies for mycoplasma-like lesions in lungs and gastric ulcers, even if it is still not clear whether tail lesions share the same predisposing factors of lung lesions and gastric ulcers, or whether tail lesions might have a role in the causality and onset of the other conditions. ABSTRACT: Tail biting is an economical and behavioral problem in the pork production system worldwide and systematic tail docking has been applied for decades to decrease the risk of its onset. However, legal and market-driven requirements are leading pig producers to rear undocked animals. The aim of this work was to monitor tail, pluck (lungs, pleurae, and liver), stomach, carcass, and thigh lesions in slaughtering pigs belonging to either docked or undocked batches. A total of 525 batches were evaluated at slaughter: 442 docked and 83 undocked batches. The presence of tail lesions was only recorded in undocked batches (44.0 ± 0.402 vs. 0.2 ± 0.2% compared to docked ones, p < 0.001), with a prevalence of severe chronic lesions of 27.3% ± 0.032, suggesting that more and alternative wide efforts to manage long-tailed animals are needed. On the contrary, docked animals showed more frequent ear lesions (9.6% ± 0.037 vs. 4.6% ± 0.019; p = 0.0001). Severe lung lesions were found more frequently in undocked animals (9.2% ± 0.043 vs. 6.6% ± 0.011, p = 0.006), as well as gastric ulcers (26.1% ± 0.021 vs. 20.3% ± 0.37, p = 0.006). These lesions might share the same predisposing factors of tail lesions; the latter might be investigated as an iceberg indicator for other pathological conditions in undocked pigs and eventual causal association among lesions in these organs should be explored.