Dogs often communicate with each other by the wag of their tail and one recent study concludes that the direction of the tail wag – left or right – is very important. The research suggests that dogs have different emotional responses to other dogs based upon the direction of the tail wag. The researchers observed that a tail swing to the right keeps canines relaxed, while a wag to the left seems to bring on distress.
Researchers used 43 pet dogs of various breeds for the study. The dogs were shown videos of other dogs wagging their tails either to the left or to the right while they wore vests that monitored their heart rate. The pets who watched one of their peers wag to the right stayed calm and often began to approach the dog on the screen. The researchers say this suggests that they saw the right-side wagging as a signal of companionship. On the other hand, the dogs that watched wagging to the left behaved more anxiously and their heart rate sped up.
The authors suggest that dogs have automatic responses from the different hemispheres of the canine brain. Study author, Giorgio Vallortigara, explains, that just as the left and right sides of the brain in humans are thought to control different emotions and behaviors, the direction of wagging might match hemispheric activation.
The researchers believe that understanding these responses in our pets may help improve dog welfare and assist in developing new strategies to keep them calm in stressful situations such as visits to the vet.
Source: Siniscalchi M, Lusito R, Vallortigara G, Quaranta A. Seeing left- or right-asymmetric tail wagging produces different emotional responses in dogs. Current Biology, 2013; 23 (22): 2279-2282.