The debate about tail docking in domestic dogs continues to rage in many developed countries and attitudes expressed by different community groups remain diametrically opposed. Veterinary associations and welfare organisations typically want the practice banned, while many breeders and pure-bred dog associations just as vigorously oppose the introduction of anti-docking legislation. In recent years, much data have been accumulated concerning the welfare implications of tail docking. A recent evaluation of this literature suggests that the practice has little to recommend it and that, in the absence of reasonable case-by-case justification, it may constitute an unacceptable abuse of a sentient species. Given this situation, it is difficult to understand why many canine interest groups, presumably representing those people who care most about the welfare of companion dogs, should continue to hold such strong attitudes in favour of tail docking. In this review we attempt to explain why different community groups might espouse strong but opposing attitudes, despite having access to the same information. We argue that the theory of cognitive dissonance, popular among social psychologists, may provide a useful framework within which to understand, and attempt to alter, attitudes that persist even though they appear contrary to available empirical evidence.