Abstract Tail docking has been practiced on dogs for many years for various reasons, including aesthetics, breeding standards and hygiene, to facilitate reproductive handling in some dog breeds, breeders’ decisions and tradition, or to prevent lesions during play or work, to name a few. Little research, however, has been done to demonstrate whether this practice causes acute pain in animals, even though it is now well known that animals, including dogs, are highly sensitive to both positive and negative stimuli. Currently, we have a broad range of methods for measuring pain that utilise diverse parameters (physiological, behavioural and metabolic), and techniques that include evaluating changes in behaviour and facial expressions, monitoring opioid and dopaminergic neurotransmission, measuring glucocorticoid levels, changes in blood hormone and lactate concentrations, the dynamics of cardiac and respiratory frequency, pupil diameter and variations in blood pressure. Many countries have banned this practice because it is deemed unnecessary, unjustifiable under any circumstances and harmful for animal welfare. The objective of the present review is to demonstrate that tail docking is a painful and unnecessary practice that presents more complications than benefits in dogs.