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We know that dogs are dedicated companions that offer unquestioning
attachment and acceptance. In the past several years, mounting
scientific evidence suggests that they benefit us even beyond
eager devotion. Numerous studies have shown that dogs -- one of
the earliest domesticated animals -- can help lower blood pressure,
ease the loneliness of the elderly in nursing homes, and help
children overcome allergies.
Now there's new research from the University of Missouri-Columbia
suggesting the hormonal changes that occur when humans and dogs
interact could help people cope with depression and certain stress-related
disorders. Preliminary results from a study show that a few minutes
of stroking our pet dog prompts a release of a number of "feel
good" hormones in humans, including serotonin, prolactin
and oxytocin.
In addition, petting our pooches results in decreased levels
of the primary stress hormone cortisol, the adrenal chemical responsible
for regulating appetite and cravings for carbohydrates.
"The notion that serotonin increased with their own dog
is a very powerful thing. Could a dog help mediate serotonin levels
in order to help depressed patients?" asks Dr. Rebecca Johnson,
a nursing professor and associate director at the Center for Animal
Wellness, Missouri University College of Veterinary Medicine,
who is heading the study with collaborator Richard Meadows.
Why does Spot make us feel better?
Dog owners may not be surprised to hear about the emotional benefits
of stroking a beloved pet, but for researchers like Johnson, it's
important to understand why Spot makes us feel better.
Therapy dogs have been used to visit nursing homes, calm traumatized
children and help ease pain in people undergoing physical rehabilitation,
but the field of animal-assisted therapy is still in its infancy,
Johnson says. Researchers are trying to determine which types
of people would best benefit from being with pet animals and how
often they need to interact with them to get results.
"By showing how interacting with pets actually works in
the body to help people, we can help animal-assisted therapy become
a mainsteam medically-accepted intervention that would be prescribed
to patients and, in the long run, be reimbursed by insurance companies,"
says Johnson. The University of Missouri-Columbia study was funded
by The Skeeter Foundation, a group headed by Dr. Jack Stephens,
founder of Veterinary Pet Insurance, a nationwide insurer of pet
medical coverage.
Johnson's study expanded on research conducted in 1999 by South
African scientists who found that 15 minutes of quietly stroking
a dog caused hormonal changes that were beneficial to both the
dog and the human.
But the South African study was small, involving only 18 people
and a few friendly dogs, and didn't test for serotonin, the brain
chemical strongly linked with depression. Increased levels of
the neurotransmitter serotonin make us more mentally alert, improve
sleep and can make us less sensitive to pain.
Comparable to eating chocolate
In the larger Missouri study, 50 dog owners and 50 non-dog owners
over the age of 18 sat in a quiet room for 15 to 39 minutes with
their own dog, a friendly but strange dog, and a robotic dog.
The robotic dog was included because electronic pooches, such
as Sony's AIBO, are being studied as a possible resource for the
elderly who can't look after a live animal.
Each session involved calm stroking or petting. Researchers checked
blood samples of both the humans and dogs at the beginning of
each session and monitored their blood pressure every five minutes.
The dogs' blood pressure dropped as soon as they were petted.
The humans' blood pressure dropped by approximately 10 percent
about 15 to 30 minutes after they began petting the animal, at
which point blood was again drawn.
Johnson's study found that serotonin levels increased when interacting
with the human's own dog, but not with the unfamiliar animal.
And serotonin actually decreased when interacting with the robotic
dog.
Dr. Alan Beck, director of the Center for the Human-Animal Bond
at Purdue University, says the serotonin changes reveal the "mechanism"
of how pets influence our health.
"It shows that there is a physiological mechanism [to relaxing
with a pet], that it really is comparable to other things we know
cause relaxation, like eating chocolate," says Beck.
Not just learned behavior
In other words, the warm feeling we get from our dogs and other
pets isn't just a learned behavior, Beck says, but something that's
hard-wired into humans so that the presence of animals can help
us stay well and even recover from illnesses.
It's a theory that's been gaining notable scientific support
for some time:
- In 1995, Erika Friedman at the University of Maryland Hospital
conducted a study involving 392 people, which found that heart
attack patients with dogs were eight times more likely to be
alive a year later than people without dogs.
- In 1999, the State University of New York at Buffalo conducted
a study involving 24 stock brokers taking medication for high
blood pressure. The researchers found that adding a dog or cat
to the stock brokers' lives helped stabilize and reduce their
stress levels.
- In 1999, Swedish researchers reported that children exposed
to pets during the first year of life had fewer allergies and
less asthma.
Recently, separate studies reported that walking a dog contributed
to a person's weight loss and that dog walking can be a catalyst
for social interaction with other people, a benefit that can
help improve our sense of well-being -- or even help us meet
a future spouse.
Studies involving other pets
While Johnson doesn't advise patients to throw away their antidepressants
and instead get a dog, she says animal therapy could be used as
an adjunct to depression treatment.
"It gives us answers about who would be the most likely
to benefit from owning a dog or how often someone would need to
visit with a dog to get the beneficial effect," she says.
And it's not just dogs that are being studied for their therapeutic
power. Currently Beck and other researchers at the Center for
the Human-Animal Bond, in conjunction with the National Science
Foundation and the University of Washington, are exploring how
the "inborn attraction to nature" can help patients
with dementia. For instance, people with Alzheimer's disease often
suffer from weight-loss problems because they're unable to focus
long enough to eat. But when they sit in front of aquariums with
brightly colored fish, the elderly patients are able to pay attention
long enough to get their meals down.
As scientific research continues to validate the importance of
animals to human health, Beck expects to see more community funding
for public dog runs, for example, as well as more widespread acceptance
of animal care as a legitimate healthcare expense.He also hopes
more insurance policies will begin offering coverage for services
such as veterinary care for pets of the elderly, and that eventually
pet owners will receive insurance discounts similar to the deals
given to non-smokers.
Just as we recognize that exercise is important to our health,
it's becoming clearer that animals can also improve the quality
of our lives, Beck says.
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