Post-reunion behavioural and physiological recovery dynamics in dogs with separation-related problems

Separation-related problems (SRP) are among the most common behavioural disorders in dogs, with considerable consequences for canine welfare and the caregiver-dog relationship. Using infrared thermography (IRT) and behavioural analysis, this study evaluated physiological and behavioural stress responses in dogs with SRP during a controlled caregiver absence in the presence of an unfamiliar person. Forty dogs were classified into an SRP group (n = 20) and a control group (n = 20) using the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). Eye surface temperature was measured using infrared thermography (IRT) before separation phase and at one, two, and three minutes following reunion. Behavioural indicators, including vocalization, spatial distribution, activity, and proximity to the unfamiliar person, were continuously coded during a 10-minute separation phase. While no baseline differences were detected between the two groups ( p = 0.437), the SRP group exhibited significantly higher eye surface temperatures compared to the control group at all post-reunion time points ( p < 0.05). Within-group analyses revealed a significant overall effect of time on eye surface temperature in the SRP group ( p < 0.001), whereas the control group showed no significant changes across time ( p = 0.494). Behavioural analyses indicated longer vocalization durations and increased door-directed behaviour at the uncorrected level in the SRP group. In contrast, the control group displayed more flexible behavioural organization. No behavioural group differences remained significant following correction for multiple comparisons. Groups did not differ in time spent in proximity to the unfamiliar person ( p = 0.358). However, despite similar proximity across groups, dogs with SRP showed elevated physiological arousal, indicating that the unfamiliar person's passive presence did not correspond with reduced arousal in this study. Correlation analyses further indicated clustering of stress-related behaviours in the SRP group, contrasting with more organized behavioural patterns in the control group. These findings support the combined use of IRT and behavioural analysis as a non-invasive approach for assessing acute stress and recovery dynamics in dogs with SRP.