There are many breeds of dog which traditionally had their tails docked such as some Spaniels, Doberman Pinchers, most Terrier types and Rottweilers. However, in 2007 this was effectively banned in the UK, with some permitted exceptions*. This ban also extended to the showing of some dogs with docked tails, with the exception of dogs who are demonstrating their working skills. Until the 1990's, lay persons were allowed to dock dogs tails, but now it is only veterinary professionals who can carry out this procedure, and even then, only under some circumstances*. This is something to bear in mind when buying a puppy as heavy fines can be imposed if someone is found to be in contravention to these regulations*.
Any dog employs a wide range of body postures and vocalisations (barks, growls, yelps for example), to communicate its emotional state to other dogs and other species, including humans. The body postures it adopts represent a large proportion of a dog's visible body language, in which the carriage and position of the tail is but one of the visible cues. Most people, who consider themselves familiar with dogs, interpret a 'dog with a waggy tail', to be friendly and approachable. This may be the case on the majority of occasions, it is not necessarily the absolute, and in the case of dogs with no tail could potentially be very difficult to interpret, and could result in undesirable or aggressive situations. In addition to dog to dog aggression, unwarranted aggression may also be directed towards other human household members, if the dog resides as part of a family group. An example of this could be a young child, who may find it difficult to interpret and understand the cues and body language a dog displays anyway. For reasons such as this, play or contact between children and dogs should always be supervised.
The issues surrounding tail docking in dogs continues to be a much debated subject. It is agreed upon by the majority of people that a dog uses its tail for communication purposes (amongst other things such as balance); however, to what extent the tails importance is in the communication process is still widely argued. The uses of the tail are well documented in veterinary and academic research and logic suggests that it the whole or part of the tail was to be amputated, then these uses may be impaired in some way.
Arguments put forward by pro docking groups (such as the Council for Docked Breeds), to support the need for docking such as fewer injuries in the field, appear to be based upon personal observations and anecdotal evidence but must be considered in the argument, whereas, anti tail docking groups argue that extensive research done by universities and the veterinary profession shows that it can be justifiably said that there is evidence that docking a dog's tail does indeed interfere with its ability to communicate effectively, both with other dogs and humans and also causes pain at the time and after docking.
In conclusion, it could be said that if this form of communication is impaired, it may lead to undesirable situations, both for the dog in question, other dogs and in some cases humans. This may lead to antagonistic or dangerous situations, in which a dog may attack if either another dog or a human misinterprets the visual cues given by its tail, but to what extent this is still widely not known.
* As defined by the Docking of Working Dogs Tails (England) Regulations 2007 and the Animal Welfare Act 2006.