Karen B. London
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Does Tail Length Matter?
Robot dog helps answer this question
The Pointer has a tail but the Lab doesn't. Hmm.


Dogs communicate with their tails in ways that are more complex than people thought even a few years ago, and new studies continue to reveal more about the information that tails convey. Many people have wondered whether dogs with docked tails or naturally short tails are less able to communicate than dogs whose tails are long and have not been docked.
In a recent study called “Behavioural responses of Canis familiaris to different tail lengths of a remotely-controlled life-size dog replica,” scientists Leaver and Reinchen investigated the importance of tail length in the initiation of social interactions in dogs. Basically, their question was whether the length of a dog’s tail made any difference to other dogs. They found that tail length does matter.
Nearly 500 dogs were videotaped when approaching a life-sized robot dog that had either a short tail or a long tail and the tail was either wagging or held still. They noted whether the dogs were hesitant in their approach to the robot dog or if they approached without such caution.
What did they find? They found that dogs were more likely to approach, without hesitating, a robot with a long wagging tail than one with a long tail that was held still. They were equally likely to approach without caution a short tail when it was still and when it was wagging. Approaches to the short tail (whether wagging or still) were more likely to be hesitant than approaches to a long wagging tail, but less likely to be hesitant than those to a long tail that was still.
The experimenters concluded that it is harder to convey information with a short tail than with a long tail. One possibility is that it is harder for dogs to obtain information from a shorter tail than from a longer tail.
I think the coolest part of this study is the use of a robot dog in the experiment. If live dogs had been used, studying the effects of tail length would have been challenging because so many other variables could have clouded the issue. With a robot, the “dog” is in the same posture, smells the same, and is not adding additional behavior into the experimental design. The different responses by approaching dogs can be explained by the only parts of the robot that are different—tail size and tail motion.



Karen B. London, PhD, is a Bark columnist and a Certified Applied Animal Behaviorist specializing in the evaluation and treatment of serious behavior problems in the domestic dog.

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Submitted by Anonymous | January 14 2011 |

Truely fascinating! Thanks for this article! I always thought it was sad to have a docked tail for that reason and now I know I was kind of right!
I love the robot dog idea too!

Submitted by Anonymous | January 15 2011 |

My Aussie has a docked tail- I will never get a dog with a docked tail again. He is always having miscommunications with other dogs despite lots of socialization as a puppy and overall good signals. But he can't express what he needs to with a vital part of his communication system missing.

Submitted by Temple | January 15 2011 |

Hopefully, one day, with more research on the importance of tails we will stop docking the tails of dogs. I'm thinking of poor baby Rottweilers for a start. This barbarism has been outlawed in Europe for many years now.

Submitted by Lisa | January 16 2011 |

I have an australian shepherd with a tail who competes in high-level dog agility. He is always compared to border collies when he weaves because he is very balanced and fluid in his movement through the weave poles. I always tell everyone it is clearly because he HAS a tail which is not there just for distinction...it clearly serves a purpose in balancing his movements. He definitely has an advantage over the Australian shepherds without tails in this sport.
If you do an Mt. Everest level of research on the subject of Australian Shepherd VS Border collie, you will see there was a bit of vanity involved in deciding how to distinguish the Aussie from the Border collie.
The tail has always been the "easy" choice for originators of many favorite breeds.
The Cardigan Corgi has a tail; The Pembroke Corgi does not.
Also true, I have a friend with four actively competing Cardigan Welsh Corgis and these dogs have a much smoother stride on the course, especially in the weave poles, than their cousins the Pembrokes.

Submitted by Anonymous | January 25 2011 |

Dogs originally evolved with tails for a reason....genetically or physically changing the tail just messes with nature

Submitted by Misty's Mom | January 27 2011 |

My Aussie doesn't seem to have the problems noted despite having a short tail. She's socialized quite a bit and doesn't have any problems with other dogs. That said; is it really a bad thing if other dogs approach a little slower as long as they're not exhibiting unusual dominance and/or aggressive behavior?

Submitted by Anonymous | February 6 2011 |

A robot?? Seriously?? Ya think real dogs can't tell a fake? Smell. Come on this is dog 101. The first thing they use is the nose.

Submitted by Karen London | February 7 2011 |

Nobody is suggesting that dogs can't tell a robot from a real dog. The question here is whether dogs react differently to a dog-like robot based on that robot's tail length and this study found that the answer to that question is yes. Dogs use visual cues in addition to those in other sensory modalities, especially prior to approach. I once had an animal behavior professor point out that reactions to items that are fakes aren't always completely different than reactions to the real thing, even when the observer is fully aware of something being a fake. He pointed out that if animals (including humans) never reacted to fakes, then Playboy and other similar magazines would not sell.

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