A glance at your dog’s expectant face and wagging tail can brighten even the worst day. And when they’re sick, we hurt, too. Now, a new study shows that this relationship runs both ways: Owners that experience long-term stress and anxiety can pass it on to their pooches. “Dogs are quite good at understanding humans,” says senior author Lina Roth, a zoologist at Sweden’s Linkoping University. “They’re definitely better at understanding us than we are at understanding them.” Indeed, a burgeoning body of literature is revealing dogs’ ability to interpret non-verbal cues in people. This skill has been honed over tens of thousands of years of living with humans. When dogs were first domesticated, individuals that could readily respond to humans—both their direct commands and their indirect body language—had a leg (or paw) up over their more wary and socially challenged counterparts. With this, however, comes a potential downside: If we’re afraid, our dogs can become fearful as well.
Stressed out Some people are naturally more anxious and emotionally reactive, a trait called neuroticism. Roth hypothesized that an owner with self-reported anxiety could cause chronic stress in their pet. The team recruited 58 dog-owner pairs in Sweden, including 33 Shetland sheepdogs and 25 border collies. The owners filled out questionnaires regarding their own personality traits and mental health as well as those of their pets. To discern stress levels in both species over a period of several months, Roth and colleagues measured concentrations of the stress hormone cortisol in their hair and fur. Cortisol naturally spikes during scary situations, but the chemical’s long-term effect is recorded in slow-growing hair and fur. Roth’s team measured a whole range of variables, such as seasonal differences in activity levels and lifestyle, but the only one that corresponded to the dog’s anxiety level was their owner’s anxiety level. In other words, an owner with a high amount of cortisol in their hair also had a dog with a high amount of cortisol. Interesting, the relationship didn’t work in the reverse direction: Roth found no evidence that anxious dogs created nervous owners, according to the study, published in the journal Scientific Reports on June 6. Instead, the dogs likely picked up on subtle changes such as differences in their owner's body odor and behaviors such as pacing, nail biting, and irritability. “At first, I was quite surprised at that. But for the dog, the owner is quite a big part of their everyday life, but the owner has the rest of their life out there,” Roth says. Stanley Coren, a dog-behavior expert and an emeritus psychologist at the University of British Columbia, said the results support ongoing evidence that “dogs read our emotions, and they respond accordingly.” Pet therapy The new finding also doesn’t suggest anxious people shouldn’t adopt dogs—far from it, Coren says. In fact, the presence of a dog just might help frazzled humans relax: The Anxiety Disorders Association of America recommends adopting a pet as a potential way to cope with the stressors of everyday life. Medical research has also shown being around dogs can lower blood pressure. Although the researchers didn’t measure any long-term health effects of an owner’s anxiety on their pet, Coren urges owners to consider their own behaviors when trying to understand what’s going on in their pups.