Ever wonder whether it would be safe to approach a dog or not? Well, it seems that what lies between you and those teeth sinking into your skin, is the direction in which that tail wags.

Researchers at the University of Trieste in Italy have conducted a new study on man’s best friends, and state that if the pooch close to you is wagging its tail to the right, then it’s safe to approach it.

However, if that same tail is wagging to the left, then you are better of staying away for it is an indication that the dog is looking to back away from you.

The finding, the boffins state, provides another example of how the right and left halves of the brain do different jobs in controlling emotions. In humans, strong activity in the brain’s left hemisphere (which controls the right side of the body) is associated generally with a sunny disposition, as well as approach behaviour, and right-brain activity with retreat, reports Nature magazine.

As a part of the study, lead researcher, psychologist Giorgio Vallortigara and his colleagues studied 30 pet dogs of different breeds that had been recruited through an obedience school at the University of Bari’s veterinary faculty.

Since dogs tend to move about constantly, the researchers had to resort to using video analysis for their study, in which they recorded each pooch’s response to either their owner, a human stranger, a cat, or a Belgian shepherd malinois, a large dog breed similar to a German shepherd.

The researchers noted that when the dogs were shown a human or a cat, their tails consistently wagged towards the right – an indication that they wanted to approach the source.

However, the dogs wagged their tails more to the left not only when they were shown the Belgian shepherd malinos, but also when they were left on their own – an indication that the source was not something desirable.

Neuroscientist Lesley Rogers of the University of New England in Armidale, Australia, said that the study would be valuable when it comes to testing animals with tails.

“This is a fascinating way to measure lateralization. It will be valuable in a range of tests, not only in dogs, but in other species with tails,” Rogers said.

The research is reported in Current Biology.