The issue to dock or not dock the tail has been under scrutiny. The standard operating procedure of tail docking, performed to prevent the common problem of tail biting, is also criticized for inflicting pain.
A University of Minnesota research team took another look at the consequences of raising pigs without tail docking under modern, confinement housing system conditions. The study was conducted to compare welfare, behavior and performance of pigs with and without tail docking.
Source: National Hog Farmer, December 30, 2016.
Overall, undocked pigs experienced more tail damage. In conclusion, the scientists reaffirm the short-term pain of tail docking seems worthwhile to protect pigs from suffering tail damage later in the grow-finish phase.