Rethinking dog stress behaviours: contextual and physiological insights from the attachment framework

While dogs' behavioural indicators of psychological stress are widely used, their function as reliable stress markers remains debated. Using the Strange Situation Procedure (SSP) as a social-stress paradigm, we evaluated contextual correlates of dog behaviours to explore their validity as stress indicators. In 64 dogs, behaviours commonly used as stress markers were video-coded and analysed via GLMMs to investigate differences across test episodes and attachment styles (secure, anxious, avoidant), while salivary cortisol, oxytocin, and rectal temperature provided a physiological framework. Episode had significant effects on shaking (p < 0.05), lip-licking (p < 0.001), paw-lifting (p < 0.001), whining (p < 0.001), head-turning (p < 0.001), sniffing the door (p < 0.001), and locomotion (p < 0.001), while attachment style significantly affected head-turning only (p = 0.004). Our findings suggest that the observed behaviours were not expressed linearly in relation to expected stress levels across the SSP episodes. This lack of linearity, combined with the divergent physiological correlates found across attachment groups-for instance, oxytocin correlated positively with lip-licking in securely attached dogs (p < 0.05), but negatively in anxious ones (p < 0.05) -, suggests that these behaviours do not function as simple stress indicators. Rather, their meaning appears to be contingent upon the individual's internal state and the socio-environmental context. We discuss our results in light of an alternative semiotic interpretative framework.