Dogs, Death, Data: How Your Companion Helps You Live Longer

You've never looked at dogs like this before. From 90% reductions in allergies to infectious disease prevention to 24% reductions in death, dogs are more than our best friends, dogs are medicine!

We’ve all heard the stories — a heroic Labrador pulls their owner from a burning building or barks for help just in time. But what if your dog was saving your life in a way far less dramatic — but far more consistent?

It turns out, the bond between humans and dogs doesn’t just tug at our hearts — it affects our health. From improved cardiovascular outcomes to lower risk of death, your dog could be quietly improving your odds of living longer and healthier — and the science backs it up.

Let’s start with a stunning statistic:

In an analysis of roughly 4 million people, dog ownership was associated with a 24% reduced risk of death.

The effect was largely driven by a 31% reduced risk of death from cardiovascular disease, and a remarkable 65% reduced risk of death in people with a prior cardiac event.

Now, I’ll caveat these findings upfront. It’s true these are observational studies, not randomized controlled trials (though we will touch on those as well). That means there’s a risk of confounding variables. However, even assuming that there are some confounders, the relationship is large and consistent.

For example, in all five studies with follow-up periods greater than 10 years, dog ownership was associated with a (27%) reduced risk of death.

And in all studies examining cardiovascular mortality, dog ownership was also associated with a (31%) reduced risk of death.

So, we’ve established that the association between dog ownership and positive health outcomes — particularly mortality and cardiovascular disease — is large and consistent.

But the astute reader will next want to know: How? If there’s a cause-effect relationship, we need a mechanism.

So, let’s review six ways your dog helps your heart, and overall health…

1. Reduced Blood Pressure

2. The Chemistry of Connection

3. Reduction of a Common Life-Altering Condition In Children

4. Increased Physical Activity

5. Slowing Cognitive Decline

6. Early Cancer and COVID Detection

1. Reduced Blood Pressure

In one randomized controlled trial, 48 men and women with stage II hypertension — all on medication to treat their high blood pressure — were randomized to either acquire a pet (dog or cat) or to a control group. They were then subjected to a mental stressor — in this case, mental math and speech tests, which reliably promote a cardiovascular stress response.

Yes, let’s do like the square root of -1 isn’t and ‘get real’ … mental math can be stressful!

Impressively, after six months of pet ownership, the increase in blood pressure caused by these mental stressors was significantly reduced — by as much as half!

You can see that here: The gray bars represent the pet group, and the black bars are the control group. Blood pressure increased in response to stressors (math and speech), but far less in participants with pets.

And, as an added benefit, the pet owners ended up performing better on the cognitive tasks.

At the beginning of the study, participants in both groups had roughly 74% correct performance. By the end of the study, the control group still exhibited the same performance level, whereas pet owners demonstrated 92% correct performance!

So, in effect, the dogs reduced the stress response AND made the participants smarter.

*Nuance Note: Sadly, there was no subgroup analysis to compare the stress response and cognitive performance specifically in dog owners versus cat owners.

So, dogs can lower your blood pressure — but they’re not just helping your heart in the physical sense. It turns out, they’ve also mastered the chemistry of connection…

2. Puppy Eyes and the Chemistry of Connection

Oxytocin has earned its reputation as the “love hormone” due to its critical role in facilitating social bonding between mothers and infants. But over the course of their domestication and evolution, dogs have cleverly co-opted this system to their advantage.

It makes perfect sense, doesn’t it?

The canine lineage has long benefited from forming close partnerships with humans. To truly tap into our social networks and secure their place by our side, they needed an entry point. And what better gateway than the very hormonal system we evolved to bond mother to infant and infant to mother?

One of the most fundamental manifestations of this social attachment is “mutual gaze” — the prolonged eye contact that fosters emotional connection between mother and child. You likely recognize this instinctively. It’s the “Aww… so cute!” reaction you experience when looking at a baby—or at a puppy.

And this isn’t merely speculation. In a landmark study published in Science, researchers observed dogs gazing at their owners and measured oxytocin levels in the owners’ urine. Remarkably, prolonged gazes from dogs significantly boosted oxytocin levels in their human companions (indicated by black circles in the graph). This effect was absent during brief gazes (white circles) and in hand-raised wolves (black boxes), underscoring that this phenomenon is unique to domesticated dogs.

Equally as intriguing, when researchers administered oxytocin to female dogs, the duration of their gaze toward their owners increased, reinforcing the positive feedback loop.

The researchers concluded that mutual gaze between domesticated dogs and humans has effectively hijacked the same neurochemical pathway used to establish the mother-infant bond, creating an oxytocin-driven positive feedback loop that cements the human-dog relationship.

This co-evolution with dogs may offer direct neuropsychological benefits for humans. Oxytocin doesn’t just foster social connection; it also acts as a natural anxiety reducer or “anxiolytic.” In fact, genetic differences in oxytocin receptors have been linked to higher risks of anxiety; and researchers are even exploring intranasal oxytocin as a potential treatment for this and other mental health conditions.

Of course, we’re still a long way from doctors handing out oxytocin nasal sprays for anxiety. The neuropharmacology is complex, and it’s difficult-to-impossible with current technology to target the specific brain regions of the brain where oxytocin is most effect. But the good news?

You don’t need a prescription to snuggle a puppy. (Although wouldn’t it be lovely if your insurance covered puppies cuddles alongside Prozac?)

The takeaway: Our bond with dogs isn’t just emotional — it’s biological. By activating the oxytocin system, our four-legged companions not only deepen social bonds but may also help ease anxiety and support better mental health.

Now, buckle up, because this next study completely floored me…

These benefits we’ve discussed so far are substantial — I think you owe your dog an extra treat. But they are only the tip of the iceberg. By the end of this letter, you’ll be giving your dog the whole bag of treats.

In the rest of this letter, reserved for paid subscribers, we review data on:

• Dogs Reduce A Common Condition in Children by 90%

• Dogs Increase Physical Activity

• Dogs Slow Cognitive Decline

• The Canine Science of Early Cancer and COVID Detection

New for premium subscribers, you can now listen to audio versions of these posts. Perfect for those who prefer listening to reading (or want to do both). Enjoy!