Molecular Biomarkers of Adult Human and Dog Stress during Canine-Assisted Interventions: A Systematic Scoping Review

Simple Summary Interactions between people and dogs may lower participants' stress levels. However, this is a fairly new area of research and there has not been a review of what we know across studies. We examined the existing research and found that human-dog interactions consistently improve some indications of human stress levels and don't seem to negatively affect dogs. However, we need to do more research to gain a better understanding of the impacts on people and dogs with a wider lens that looks at more markers of stress. Positive relationships, including those between humans and other animals, particularly dogs, may be a way to reduce stress in humans. However, research into this area is relatively new, and a comprehensive review of the impacts of these interactions on humans and dogs has not been conducted. A scoping review of the scientific literature was conducted to explore what is known about the impacts of canine-assisted interventions on molecular biomarkers (e.g., cortisol and oxytocin) and associated measures (e.g., heart rate and blood pressure) of human and canine stress. As reported across 27 identified studies, canine-assisted interventions have consistently been demonstrated to elicit positive changes in human stress markers, and typically do not cause negative impacts on the studied canine stress markers. However, results were inconsistent across measures of stress. For example, in humans, it was common for a study to show improvements to cortisol levels but no change to self-reported stress, or vice versa. Many of the reviewed studies also had significant methodological issues, such as not aligning the timing of sample collections to when the analyzed stress biomarkers could be expected to peak. More rigorous research should be conducted on the impacts of canine-assisted interventions on a wider range of stress biomarkers.