Istockphoto

Ask any of America’s hundred-million-plus pet owners if their animal companions make life a little sweeter, and you’re bound to hear a gleeful purr. Our critters make us so happy that, in return for their company, we willingly scoop poop, clean cages, shell out for organic kibble, and stock an arsenal of supplies to help cope with all that hair.

We clearly think they’re worth it—and maybe they truly are. A wealth of studies suggests that pets are good for your health, sometimes in unexpected ways. The right pet can lower your risk for heart disease, curb stress, and even sniff out serious illnesses. In fact, the more attached you are to your pet, the stronger its protective health benefits may be.

Of course, not all pets are created equal. Some, in fact, are dangerous. So we asked three animal authorities to dig into the research and cough up (sorry, we couldn’t resist) America’s Healthiest Pets. Read on to see if your “best friend” is on our list of six winners.

1. Dogs
The scientific findings are full of good news for the nearly 40% of us who own dogs; that number includes President Obama, who recently made good on a family campaign promise to his daughters and adopted an allergy-friendly Portuguese Water Dog.

“The breadth and depth of what dogs do to benefit humans’ happiness and longevity is pretty remarkable,” says judge Marty Becker, DVM, author of The Healing Power of Pets. Studies link dog ownership to lower blood pressure, cholesterol, and triglyceride levels. And dog owners seem to live longer after a heart attack and get more exercise than nonowners. You’re more likely to stroll with a dog than solo, and Fido may even beat your best girlfriend as a motivating force: Unlike humans, dogs never need an arm-twisting to take a brisk walk.

Then there’s the mood-boosting benefit. “Simply petting a dog is like a spa treatment,” Dr. Becker says. “After just a minute or two you have this massive release of positive neurochemicals like dopamine and serotonin. And the dog gets the same relief.” Add to that the role canines play as service companions and the striking ways that they’re contributing to medicine—from detecting cancer to predicting epileptic seizures—and there’s really no argument (except from cantankerous cat people) that man’s (and woman’s!) best friend is aptly nicknamed.

What kind of dog is best? Dr. Becker especially sings the praises of small, mixed-breed shelter pups. Small is good because “you can take the dog with you and fully integrate her into the fabric of your life,” he says.

Sadly, despite the chatter about the First Family’s search for a hypoallergenic dog, no breed is truly allergy-proof, says judge Gregg Takashima, DVM, board chair for the Delta Society, a nonprofit organization that helps connect people with service and therapy animals. Dander—tiny flakes of animal skin—is the true source of trouble.

But because pet hair may also play some role, breeds that don’t shed much, like poodles or poodle mixes (labradoodles, golden-doodles, and so forth), and the Portuguese water dog (the Obamas’ choice), are better bets for some people with allergies. Another tip to reduce allergic reactions: Bathe your pet once a week with a nonsoap shampoo that’s perfume and additive-free, Dr. Takashima says.

But if doggie upkeep just isn’t for you? Piggyback on the health perks of dogs by spending time with their owners. Join your neighbor on her daily walk with her pup, and her benefit is yours, too.

Next page: Cats