Nothing compares to the joy of coming home to a loyal companion. The unconditional love of a pet can do more than keep you company. Pets may also decrease stress, improve heart health, and even help children with their emotional and social skills.

An estimated 68% of U.S. households have a pet. But who benefits from an animal? And which type of pet brings health benefits?

Over the past 10 years, NIH has partnered with the Mars Corporation’s WALTHAM Centre for Pet Nutrition to answer questions like these by funding research studies.

Scientists are looking at what the potential physical and mental health benefits are for different animals—from fish to guinea pigs to dogs and cats.

Possible Health Effects

Research on human-animal interactions is still relatively new. Some studies have shown positive health effects, but the results have been mixed.

Interacting with animals has been shown to decrease levels of cortisol (a stress-related hormone) and lower blood pressure. Other studies have found that animals can reduce loneliness, increase feelings of social support, and boost your mood.

The NIH/Mars Partnership is funding a range of studies focused on the relationships we have with animals. For example, researchers are looking into how animals might influence child development. They’re studying animal interactions with kids who have autism, attention deficit hyperactivity disorder (ADHD), and other conditions.

“There’s not one answer about how a pet can help somebody with a specific condition,” explains Dr. Layla Esposito, who oversees NIH’s Human-Animal Interaction Research Program. “Is your goal to increase physical activity? Then you might benefit from owning a dog. You have to walk a dog several times a day and you’re going to increase physical activity. If your goal is reducing stress, sometimes watching fish swim can result in a feeling of calmness. So there’s no one type fits all.”

NIH is funding large-scale surveys to find out the range of pets people live with and how their relationships with their pets relate to health.

“We’re trying to tap into the subjective quality of the relationship with the animal—that part of the bond that people feel with animals—and how that translates into some of the health benefits,” explains Dr. James Griffin, a child development expert at NIH.