October 26, 2019 ANGUS CHEN
Hugging
a dog is one life's greatest joys. Getting to see fur on four legs and a
wagging tail is like experiencing a love drug — quite literally.
Dogs
and humans that interact with one another get a jolt of oxytocin,
the so-called "cuddle hormone." And, if you get to look at dogs and
hug them every day, you just might live longer than people who don't have to
clean animal hair off their clothes, according to a pair of studies out this
month.
The
studies, published in the journal Circulation: Cardiovascular
Quality and Outcomes, suggest that dog ownership is
linked to a 21% reduction in the risk of
death — over the 12-year period studied — for people with heart disease. Those
studies complement a body of literature linking dogs to good health.
Dr.
Dhruv Kazi, a cardiologist and health economist at the Beth Israel Deaconess
Medical Center and Harvard Medical School, wrote an accompanying editorial for
the new studies but was not involved with the research.
"When
you look at the big picture and look at all the evidence around dog ownership
and cardiovascular health, it's pretty clear the signal is real and likely
causal," he says.
In
other words, he's convinced getting a dog improves your health — especially for
those with heart disease.
The
research is not definitive, though, Kazi adds.
"They're
not randomized trials, the gold standard for what we would do to evaluate a new
drug," he says.
Ideally,
Kazi says, researchers would conduct an experiment where 1,000 people get a dog
and 1,000 people get a stuffed animal. Then the researchers would try to
measure how their health changed afterward. Instead, these studies looked at
data from dog owners and people without pets from national registries in
Europe.
WBUR
spoke with Kazi about dogs, their effect on health and why you might want to
consider becoming a dog person.
This
interview has been edited for length and clarity.
What
have researchers observed in the past when it comes to the health benefits of
dog ownership?
We've
known forever that owning a dog increases one's physical activity. Regardless
of weather, you have to get out and walk the dog. Otherwise, you might be
tempted to stay home and watch TV.
There
are other effects that we've known for a while. There is the idea that owning a
dog makes you spend more time outdoors, and time spent outdoors improves health
and, specifically, cardiovascular health.
But I
think the biggest advantage of having a dog is what it does for mental health.
We see very beneficial effects on depression, on anxiety, etc.
We've
had programs where therapy dogs walk through the residency rooms and interact
with patients. You see people light up. Unless you have a friend or family
member by you all day, it's an incredibly lonely experience in the hospital. To
have this animal walk by and, you know, offer you its unconditional love. That
tail wag has the ability to make that day, and I see that all the time in the
hospital.
Owning
a dog or interacting with a dog even for a short term reduces blood pressure,
improves your cholesterol profile. All of these taken together, we imagine,
would improve cardiovascular health.
These
two most recent studies suggested that dog ownership reduces the risk of death
from any cause for people with cardiovascular disease — not just heart attacks.
What did they do in these studies?
In one
case, it was what we call a meta-analysis. It looked at all prior literature on
dog ownership and heart health and showed there's an effect of dog ownership on
mortality from any cause and cardiovascular mortality.
In
another study, [researchers] looked over a 12-year period at dog owners in
Sweden who have cardiovascular disease. They adjusted for the kinds of things
we know affect cardiovascular health — age, demographics, socioeconomic status,
marital status, number of children at home — and even after adjusting for all
of that, they found a benefit of dog ownership.
How
much was that benefit?
In the
Swedish study, they followed over 100,000 people and found a 21% reduction in
deaths from any cause. In particular, I found it very convincing and striking
that the benefits seems to be larger among individuals who live alone compared
to multiperson households. That suggests the companionship of a dog is possibly
very important to their heart health.
That
seems like a massive benefit, doesn't it?
Yeah.
You know, I'm reluctant to hang my hat on that number because it may be that
some of the effect is because healthier people own dogs, and etc. Well, let's
say it's 15% not 21%. That's an intervention that is relatively low risk and
could have a substantial mortality benefit. Doctors should feel comfortable
discussing dog ownership with their patients in the right setting. In
individuals who are able to — this is a therapy worth trying. But you also
wouldn't get a dog just for cardiovascular health. In the end, you have to have
the space in your life to accommodate an animal and a friend.
But I
think that Americans have generally internalized the benefits of having a dog.
At this point, there are more pet dogs in
the U.S. than kids under the age of 18.
Or
maybe they've internalized the health consequences of having kids.
Right,
[laughs]. That could be true, too.
Do
you have a dog yourself?
I
don't, but I've wanted one for 40 years. I think these studies have finally
convinced me to get one. I think we've thought of dogs as a form of comfort, a
luxury even. For me, the study forces a rethinking of pets in our society.
We've started out with dogs as accomplices during hunts as hunter-gatherers.
Gradually,
we selected for traits of loyalty and friendship. At this point, society —
particularly Western society — is very individualistic and fragmented. I can
totally see the rationale for why dogs improve our sense of well-being, reduce
loneliness, improve self-esteem and can be a boost to our physical and mental
health.
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