Heart rate variability and saliva cortisol assessment in shelter dog: human-animal interaction effects

The aim of this study is to investigate the effects of a human interaction program on shelter dogs and to determine the effect on canine heart rate variability, behaviour, and salivary cortisol levels. Twenty dogs were behaviourally (temperament tests) and clinically (full cardiologic examination) pre-tested and then matched in two homogenous groups. Ten dogs (group A) were submitted to a human interaction program and compared to a control group (group B). The study included four experimental sessions (T0, T1, T2 and T3). At T0 salivary cortisol samples (basal cortisol) were collected from all dogs. After 1 week, all dogs were submitted to the following procedures: electrocardiogram holter monitor unit application and recordings, saliva cortisol sample collection before behavioural test (pre-test cortisol), behavioural test application, and saliva cortisol sample collection after behavioural test (post-test cortisol). The above-mentioned experimental session was repeated every 4 weeks from the beginning of the study (T1, T2 and T3). All dogs were videotaped during all behavioural evaluations. Significant differences (P < 0.05) between groups A and B were determined for heart rate variability (HRV) frequency domain (5 min analysis): low frequency/high frequency ratio (LF/HF) at T1; LF/HF and standard deviation of time duration between two consecutive R waves (RR interval) of the electrocardiogram (SD RR) at T2; very low frequency (VLF) at T3. Overall behavioural test holter recordings showed statistical differences (P < 0.05): LF/HF at T1 and T2, total number of interpolated beats and total number of used beats at T3. Behavioural data showed significant improvements in sociability/diffidence and temperament in group A for some tests (P < 0.05). A significant decrease (P < 0.05) in salivary cortisol levels between T1 vs T2 and between T1 vs T3 has been reported. HRV and behavioural data reported significant correlations in some tests, as well as cortisol levels and behavioural data (P < 0.05). These data suggest that human interaction supplement sessions have a positive effect upon the behaviour and they could affect the physiological indicators of animal welfare.