Tail-biting, ear-biting, flank-biting or navel sucking behavior can be serious in groups of growing pigs, particularly when confounded by secondary bacterial infections. Through careful observation, one can often identify the few individuals within an affected group that are responsible for the abnormal behavior and are inflicting trauma on numerous pen-mates. The cause of the offending behavior is too often simply ascribed to “stress.” A disciplined approach is required to identify the true source(s) of the stress, which may include: facility limitations (inadequate feed or water space, overstocking), nutritional compromise (mineral or salt imbalances in rations, maladjustment immediately post weaning), environmental inadequacies (drafts, full effluent pits, temperature variation, high humidity), or management factors (co-mingling pigs, out-of-feed events, poor hygiene, concurrent infectious diseases). Control requires careful observation at two levels, first to accurately identify the offending pigs and second, to identify the risk factors that may be contributing to the aggressive behavior. It is important that the aggressive pigs be separated from the group to prevent more cases. In addition to being removed to a hospital pen environment, pigs with severe lesions will likely require systemic antibiotic therapy to prevent extension of bacterial infections locally or systemically. The administration of anti-inflammatory medication may also be warranted. Concurrently, the risk factors and potential contributors to stress should be systematically analyzed and eliminated.