Effects of Presence of a Familiar Pet Dog on Regional Cerebral Activity in Healthy Volunteers: A Positron Emission Tomography Study

Abstract

ABSTRACTThis study investigated the effects of the presence of a familiar pet dog on brain activity and psychophysiology in human volunteers. Fourteen participants (2 men, 12 women; mean age ± SD = 43.0 ± 10.8 years) were enrolled in the study. Uptake of 18F-2-fluoro-2-deoxyglucose ([18F]FDG) on whole-brain positron emission tomography (PET) scans in the presence (but without interaction) and absence of their own pet dog was analyzed. In addition, an electrocardiograph was recorded to assess heart rate variability. Psychological condition was determined using the Stress Response Scale-18 (SRS-18). PET brain images were analyzed and compared between the two conditions (t-tests; p < 0.001) using a statistical parametric mapping program (SPM-5). Deactivated brain areas were detected in the left middle frontal gyrus (Brodmann area: BA 8), the right fusiform gyrus (BA 20), the left putamen, and the thalamus in the presence of the pet dog, indicating reduced regional brain activities associated with stress perception and sympathetic arousal. Similarly, SRS-18 scores were significantly lower (p < 0.05) in the presence of the pet dog, indicating a lowered stress response. However, autonomic function was not found to differ significantly between the two conditions. Overall, these results suggest that the participants were “relaxed” in the psychological sense. PET with [18F]FDG appears to be a useful tool for examining the brain mechanisms underlying the psychophysiological well-being associated with the human–animal bond in terms of regional brain responses.