Tail biting: What your pigs are trying to tell you

Few things are more frustrating in a pig barn than discovering pigs with chewed or bleeding tails. Tail biting can appear suddenly and spread quickly within a pen. By the time the problem becomes obvious, several pigs may already be injured. Some producers describe tail biting as something that “just happens.” In reality, tail biting rarely occurs without a reason. In many cases, tail biting is a signal that something in the pigs’ environment or management has changed.

Pigs respond quickly to changes in their surroundings. When conditions in the barn become stressful or disruptive, their behavior often changes before other warning signs appear. Tail biting is one of those behavioral changes. Rather than viewing it as random misbehavior, it can be helpful to think of tail biting as an indicator that pigs are responding to something in their environment. Several common disruptions in the barn can increase the risk of tail biting. Limited feeder access, inconsistent feed delivery, overcrowding, poor air quality, temperature fluctuations, or equipment problems can all contribute to increased activity around pen mates’ tails.

Another important point is that not every pig in a pen plays the same role during a tail biting event. In many cases, only one or a few pigs begin chewing on the tails of pen mates. These pigs are often referred to as “biters.” At the same time, certain pigs may receive most of the tail damage and become the “victims.” However, these roles are not permanent. A pig that begins biting may later receive tail damage, and a pig that was previously bitten may begin chewing on other pigs’ tails. These roles can shift quickly within a pen, sometimes within minutes or hours, but in other cases pigs may change roles days or even weeks later. Because of this, a problem that begins with one pig can spread through a group quickly before it becomes obvious.

It is also important to remember that tail biting is a behavior. While tail docking reduces the length of the tail available to bite, it does not eliminate the behavior itself. Tail biting can still occur in both docked and undocked pigs if the conditions that contribute to the behavior are present. This is why identifying the environmental or management factors driving the behavior remains an important part of controlling outbreaks.

Tail biting often begins with tail manipulation. Producers may notice pigs repeatedly nosing or chewing on the tail area of pen mates before visible injuries appear. Once the tail becomes damaged and bleeding begins, additional pigs may be attracted to the wounds. At that point, the behavior can escalate quickly across the pen.

When tail biting begins to appear, it is often useful to step back and evaluate what may have recently changed in the barn. Has feeder access become limited as pigs grow? Has feed delivery been inconsistent? Has ventilation changed or temperatures fluctuated? Even small disruptions in daily routines or equipment can influence pig behavior.

Environmental management also plays a role in preventing tail biting. Pigs naturally spend time rooting and exploring their environment. Providing materials that pigs can manipulate can help redirect their attention away from pen mates. Simple materials such as ropes, chains, or other durable hanging objects can give pigs something to investigate besides the tails of other pigs.

Ultimately, pigs communicate a great deal through their behavior. When tail biting appears in a pen, it is often a signal that something in the environment deserves a closer look. By identifying and correcting the underlying cause early, producers can limit how far the problem spreads and keep pigs healthier and more productive.

Courtney Archer, Ph.D., is a swine Extension specialist, University of Illinois Urbana-Champaign.