What does a dog’s tail wag mean?

Scientists have recently found that a tail wag to the left has a completely different meaning than one to the right.  Dogs actually respond differently when they see their fellow fur-friends wag their tail to the left than they do when they wag to the right. These findings were reported in the Cell Press journal Current Biology on Oct. 31^st.  Dogs like humans have asymmetrically organized brains, with the left and right sides being used for different functions.

So what does a tail wag really mean?  When dogs wag their tail to the right, they are conveying positive emotions (like seeing their owner). On the other hand, a tail wag to the left transmits negative emotions (when seeing an unfriendly dog). This tail activity is actually reflecting the inner workings of the brain! Much like humans left brain activity produces a right tail wag whereas right brain activity triggers a tail wag to the left side (much like humans whose left brain hemisphere controls the right hand and vice versa).

Can dogs notice the different tail wags among their pet peers? Well it turns out the answer is YES – whether unconsciously or not is unknown. In the study researchers monitored the reactions of dogs while showing them videos of other dogs with either left-or right-asymmetric tail wagging. When the dogs saw another dog wagging to the left, their heart rates picked up and they began to look anxious. When dogs saw another dog wagging to the right, they stayed perfectly relaxed.

“The direction of tail wagging does in fact matter, and it matters in a way that matches hemispheric activation,” says Giorgio Vallortigara of the Center for Mind/Brain Sciences of the University of Trento. “In other words, a dog looking to a dog wagging with a bias to the right side — and thus showing left-hemisphere activation as if it was experiencing some sort of positive/approach response — would also produce relaxed responses. In contrast, a dog looking to a dog wagging with a bias to the left — and thus showing right-hemisphere activation as if it was experiencing some sort of negative/withdrawal response — would also produce anxious and targeting responses as well as increased cardiac frequency. That is amazing, I think.”

There is no evidence to suggest the dogs are intentionally communicating those emotions to other dogs. It is more likely an instinctual response.

So the next time you see a dog’s tail wagging you’ll know exactly what he/she is thinking! A dog’s bark?…well that’s another story!