St. Louis ? First, horses were replaced with cars. Then carrier pigeons were put out of work by radios. Now it’s dogs who may need to look over their shoulders.

They have reason to worry, according to a St. Louis University study that pitted a robotic canine against the real thing in a contest to see which was better at relieving the loneliness of nursing home residents.

In a final analysis likely to shock dog lovers – lovers of real dogs, that is – the two creatures finished in a virtual tie.

Among the shocked dog lovers is the study’s author, Dr. William Banks, a professor of geriatric medicine at St. Louis University.

“I kind of assumed the live dog would do better,” Banks said.

It doesn’t make it any easier knowing it was his own dog, Sparky, a 35-pound, sandy-red, floppy-eared pooch, who failed to outdo the robotic Aibo, which was made by Sony until 2006.

And it’s not like Sparky was a novice in this arena. The 9-year-old animal is a trained therapy dog. He’s been taught to make people feel good.

“He’s a pro,” Banks said. “He’s got this incredible personality.”

But it wasn’t enough to overcome a hairless robot programmed to mimic the behavior of real dogs. It barks, wags its plastic tail and learns basic commands. It can even chase a ball.

“It’s really frightening,” Banks said. “Whoever engineered the behavioral software – they must have some insight into the human psyche.”

The study, published in the March issue of the Journal of the American Medical Directors Association, was done on a tight budget, with Banks and his wife, co-researcher Marian Banks, supplying the labor and both dogs.

Testing took place during six weeks of visits to a trio of local nursing homes. Banks would not reveal the names, citing privacy concerns.

But what does this all mean – beyond the notion that nursing homes would be happier places if robot dogs roamed the halls. After all, you can’t even buy a new Aibo anymore, though you can snag a used one on eBay or another online auction site.

Banks sees a day when robots could be used to help older people remain independent longer. The machine could be programmed to follow you around, monitoring vital signs, reminding you when to take medicine, or even calling for help if needed.