# Puppy Love: Pets and serotonin



## David Baxter PhD (Jul 22, 2004)

Puppy Love
July 21, 2004
by Karen Lurie. ScienCentral

*Pooch Pick-Me-Up*
Any dog owner can tell you about the benefits of spending time with a furry friend. But now there's some science to back it up. 

"We have known for a long time that people like to interact with dogs and that it makes them feel happy and they enjoy it," says Rebecca Johnson, a gerontologist at University of Missouri-Columbia's Sinclair School of Nursing. "But it's important to know how this affects the changes in their bloodstream, so we can see which patients might be the best to benefit from this kind of interaction."

In her on-going study, Johnson asks 50 dog owners and 50 non-pet owners, with ages ranging from 19 to 73, to play with a live dog and a robot dog. Before and after the interactions, she draws blood samples from human and dog, to compare hormone levels. "One of the hormones that we are interested in, which is called serotonin, is the hormone that controls depression in people," Johnson explains.

Johnson's preliminary results show that serotonin increases when people pet their own dogs. "We think this is very important because of the large numbers of people in this country and abroad that are depressed, particularly the elderly, that we think may benefit from this kind of interaction," says Johnson. However, interaction with an unfamiliar dog didn't affect serotonin levels. 

When it came to the robotic dog, serotonin levels actually dropped. "There are two extremes with the robot dog," Johnson explains. "We find people that really are fascinated by it and like it a great deal, and then there's the other extreme, where people say, 'This could never be like a live dog, I would never want it, it's silly it's awful and it's boring'. So there are the two extremes and certainly the chemical changes in terms of the serotonin have not been beneficial with the robot dog."

What was most interesting to Johnson and her colleagues was the fact that the dogs in the study all benefited from human interaction, whether they previously knew the person or not. Veterinarian Richard Meadows measured the dogs' blood pressure and blood hormone levels during the test period. "It's both good for the dog and it's good for the person, and this appears at this state to be almost universally true," he says. "Animal rights people would have concern that we are doing something stressful to the animals. Dogs are …gregarious and enjoy other company, but we didn't want to cause any harm to the animals."

Sandra Barker, director of the Center for Human-Animal Interaction at Virginia Commonwealth University, which promotes understanding the health benefits of interacting with companion animals. She visits hospital patients with her therapy dog named H.I., and she sees first-hand how a pooch can help draw someone out of depression. Barker hopes Johnson's research will promote animal therapy in hospitals and nursing homes. "You see people smiling when a dog enters the room…and if we know the mechanisms, we can come up with alternative treatment recommendations. I think the potential is there." 

Johnson says she is looking at the type of patients that might benefit most from the dog-petting experience. "My intent is to do this type of work with older people who are newly relocated into nursing homes, because there is a great deal of anxiety and depression among them," says Johnson. "Pet the animal, have some companionship with the animal, and have the beneficial serotonin changes."

Johnson's research was presented at the _Companion Animals: Fountains of Health_ conference at the Autonomous University of Barcelona and was funded by the Veterinary Pet Insurance Skeeter Foundation.


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