I segnali calmanti nel cane: da mito a realtà scientifica? [Calming signals in dogs: From myth to scientific reality?]

Visual communication in dogs (especially postures and muzzle expressions) plays an important role in the management of intraspecific interactions. At the end of Eighties Turid Rugaas described the so-called "calming signals", considered as a crucial part of canine communication. The aim of the current research was to assess whether the display of the "calming signals", according to Rugaas, can reduce the intensity of aggression during intraspecific interactions in domestic dogs. Twenty-four dogs met, under standardised and randomized conditions and in couples, 4 different subjects (a dog of the same sex familiar, of the same sex unfamiliar, of the opposite sex familiar and of the opposite sex unfamiliar), off-leash and free to interact for 5 minutes. All the 96 meetings have been videorecorded and then analysed in order to register the number of emissions of 21 "calming signals". Moreover, it has been evaluated whether, after the display of a calming signal by the attacked dog, the intensity of aggression in the other dog would decrease. The statistical analysis was carried out through the χ2 and Wilcoxon tests. All aggressions have been followed by the display of one or more calming signals by the other dog. In 72.6% of cases the level of aggression in the aggressor decreased: such reduction is therefore statistically more likely than the increase or the stability of the aggression intensity. Results of the current research seem to confirm the hypothesis that in dogs visual signals with a calming effects on conspecifics exist, and that they can prevent an escalation of aggression.