A new study will explore whether living with a dog encourages the growth of positive microorganisms in the human gut—enough to improve physical and mental health in older adults.
“We’ve co-evolved with dogs over the millennia, but nobody really understands what it is about this dog-human relationship that makes us feel good about being around dogs,” says Kim Kelly, an anthropology doctoral student at the University of Arizona and one of the primary investigators on the study.
“Is it just that they’re fuzzy and we like to pet them, or is there something else going on under the skin? The question really is: has the relationship between dogs and humans gotten under the skin? And we believe it has.”
Are Dogs Like Yogurt?
The human digestive system is home to more than 500 different types of bacteria, both “good” and “bad.” Probiotics often are called “good” or “helpful” bacteria because they help keep the intestines healthy and assist in digesting food; they also are believed to help the immune system. Foods such as yogurt, as well as supplements, can help enhance probiotics in the body.
“We essentially want to find out, is a dog acting like yogurt in having a probiotic effect?” says Kelly, who also is a principal research specialist in the department of psychiatry and program coordinator for the Human-Animal Interaction Research Initiative.
Existing research shows that dogs and their owners share much of the same gut bacteria over time. In addition, some studies have shown that dogs enhance immune functioning in children, reducing the risk for immune disorders, such as asthma and allergies.
“We think dogs might work as probiotics to enhance the health of the bacteria that live in our guts. These bacteria, or ‘microbiota,’ are increasingly recognized as playing an essential role in our mental and physical health, especially as we age,” says Charles Raison, principal investigator for the study and a professor of psychiatry in the University of Arizona College of Medicine.
“We know that not all bacteria are good. We can get very sick from the ‘bad’ bacteria, and modern medicine has done a wonderful job of protecting us from various diseases that are created by these bacteria,” says Raison, also a professor of family and consumer sciences. “But unfortunately, by eliminating the bad bacteria we’ve started eliminating the ‘good’ bacteria, too.”
Participants in the study, which is being conducted in partnership with the Humane Society of Southern Arizona, will be paired with a canine companion from the humane society and live with the dog in their home for three months.