Fuzzy Math: How Do “Dog Years” Work?

My next-door neighbors have a little terrier named Melvin (not pictured). My old neighbor had a very big Bernese mountain dog (also not pictured). I didn’t know its name, and usually just referred to it as The Big Dog or The Beast. Ten Melvins, soaking wet and carrying a few dollars in change in their mouths, would probably weigh about the same as The Big Dog. The Big Dog could probably eat all ten of those Melvins, and the change, and still be hungry.

In other words, no two dog breeds are created equal, even if all dogs go to heaven. They come in different shapes and sizes. They reach maturity at different ages and time takes its toll on their bodies differently. On average, smaller dogs like Melvin have longer lifespans (14-16 years) than big ones (12-13 years), which have longer lifespans than certain “giant breeds” like the Bernese (7-10 years).

Age is an important piece of social information and can tell you a number of things about a person. Since dogs are social creatures and are part of many of our social circles, it’s nice to have that information about them, too. With the way different breeds mature and age at different rates, though, things can get confusing. A five-year-old terrier isn’t at the same point in its life as a five-year-old Great Dane. In fact, the two dogs are pretty much at opposite ends of their lifespans.

To work around this snag, people have long followed the rule that “dog year” is equal to seven human years and multiplying a dog’s age by seven gives you its age in the context of the human lifespan. The x7 trick is easy enough to do, but it’s no more helpful than just giving the dog’s age in dog years.

A five-year-old terrier and a five-year-old Great Dane are not only unlike each other in age, neither is similar to a 35-year-old human.

The dog year to human year conversion is especially inaccurate with very young dogs. A dog that’s one year old would be seven years old in human years. Most dog breeds are sexually mature and fully capable of reproducing when they’re one year old, while most seven-year-old humans are not. One just wants a puppy, but the other can make puppies.

Crafting a simple, proportional relationship between Rover’s age and yours might seem convenient, but it’s not doing anyone good. While no one formula for dog-to-human age conversion is scientifically agreed on, we can at least say that there are some better alternatives to multiplying by seven.

New Math

The folks at The Dog Guide suggest that when we think about “dog years,” we have to consider the breed and calculate accordingly. Across the board, they say, you can consider the first year of a dog’s life as equivalent to 15 or so human years. By that time, dogs and humans are approaching their adult size and have reached sexual maturity. On their 2nd birthday, you should add about 3-8 more years to your dogs “human age,” depending on size, and value each dog year as being worth 4-5 human years from that point on.

Stanley Coren, psychologist and author of How Dogs Think, The Pawprints of History and other dog books, uses a similar system. The way he sees it, one-year-old dogs and two-year-old dogs are like 16-year-old people and 24-year-old people, respectively, regardless of breed. For the next three years, each birthday tacks on five human years, and from age five and beyond, everything depends heavily on the dog’s size. Coren suggests adding four years of human life to the age of small dogs after age 5, and six years for large breeds.

When you’re crunching these numbers for your own dog, you should also keep in mind individual characteristics like weight, diet, exercise and veterinary care. If you have a terrier that weighs the same as a Bernese mountain dog, it’s a safe bet that the little porker’s lifespan is going to be decreased. If you keep your dog healthy, lean and on a quality diet, though, then they’ll skew a little younger in human years when the conversion system provides a little wiggle room.

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10 Scientific Benefits of Being a Dog Owner
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iStock

The bickering between cat people and dog people is ongoing and vicious, but in the end, we're all better off for loving a pet. But if anyone tries to poo-poo your pooch, know that there are some scientific reasons that they're man's best friend.

1. YOU GET SICK LESS OFTEN.

Dog snuggling on a bed with its person.
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If cleaning commercials are to be believed, humanity is in the midst of a war against germs—and we shouldn't stop until every single one is dead. In reality, the amount of disinfecting we do is making us sicker; since our bodies are exposed to a less diverse mix of germs, our entire microbiome is messed up. Fortunately, dogs are covered in germs! Having a dog in the house means more diverse bacteria enters the home and gets inside the occupants (one study found "dog-related biodiversity" is especially high on pillowcases). In turn, people with dogs seem to get ill less frequently and less severely than people—especially children—with cats or no pets.

2. YOU'RE MORE RESISTANT TO ALLERGIES.

Child and mother playing with a dog on a bed.
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While dog dander can be a trigger for people with allergies, growing up in a house with a dog makes children less likely to develop allergies over the course of their lives. And the benefits can start during gestation; a 2017 study published in the journal Microbiome found that a bacterial exchange happened between women who lived with pets (largely dogs) during pregnancy and their children, regardless of type of birth or whether the child was breastfed, and even if the pet was not in the home after the birth of the child. Those children tested had two bacteria, Ruminococcus and Oscillospira, that reduce the risk of common allergies, asthma, and obesity, and they were less likely to develop eczema.

3. YOU'LL HAVE BETTER HEART HEALTH.

Woman doing yoga with her dog.
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Everything about owning a dog seems to lend itself to better heart health. Just the act of petting a dog lowers heart rate and blood pressure. A 2017 Chinese study found a link between dog ownership and reduced risk of coronary artery disease, while other studies show pet owners have slightly lower cholesterol and are more likely to survive a heart attack.

4. YOU GET MORE EXERCISE.

Person running in field with a dog.
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While other pets have positive effects on your health as well, dogs have the added benefit of needing to be walked and played with numerous times a day. This means that many dog owners are getting 30 minutes of exercise a day, lowering their risk of cardiovascular disease.

5. YOU'LL BE HAPPIER.

Woman cuddling her dog.
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Dog owners are less likely to suffer from depression than non-pet owners. Even for those people who are clinically depressed, having a pet to take care of can help them out of a depressive episode. Since taking care of a dog requires a routine and forces you to stay at least a little active, dog owners are more likely to interact with others and have an increased sense of well-being while tending to their pet. The interaction with and love received from a dog can also help people stay positive. Even the mere act of looking at your pet increases the amount of oxytocin, the "feel good" chemical, in the brain.

6. YOU HAVE A MORE ACTIVE SOCIAL LIFE.

Large bulldog licking a laughing man.
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Not only does dog ownership indirectly tell others that you're trustworthy, your trusty companion can help facilitate friendships and social networks. A 2015 study published in PLOS One found that dogs can be both the catalyst for sparking new relationships and also the means for keeping social networks thriving. One study even showed that those with dogs also had closer and more supportive relationships with the people in their lives.

7. YOUR DOG MIGHT BE A CANCER DETECTOR.

Man high-fiving his dog.
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Your dog could save your life one day: It seems that our canine friends have the ability to smell cancer in the human body. Stories abound of owners whose dogs kept sniffing or licking a mole or lump on their body so they got it checked out, discovering it was cancerous. The anecdotal evidence has been backed up by scientific studies, and some dogs are now trained to detect cancer.

8. YOU'LL BE LESS STRESSED AT WORK.

Woman working on a computer while petting a dog.
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The benefits of bringing a dog to work are so increasingly obvious that more companies are catching on. Studies show that people who interact with a pet while working have lower stress levels throughout the day, while people who do not bring a pet see their stress levels increase over time. Dogs in the office also lead to people taking more breaks, to play with or walk the dog, which makes them more energized when they return to work. This, in turn, has been shown to lead to much greater productivity and job satisfaction.

9. YOU CAN FIND OUT MORE ABOUT YOUR PERSONALITY.

Man running in surf with dog.
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The kind of dog you have says a lot about your personality. A study in England found a very clear correlation between people's personalities and what type of dogs they owned; for example, people who owned toy dogs tended to be more intelligent, while owners of utility dogs like Dalmatians and bulldogs were the most conscientious. Other studies have found that dog owners in general are more outgoing and friendly than cat owners.

10. YOUR KIDS WILL BE MORE EMPATHETIC.

A young boy having fun with his dog.
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Though one 2003 study found that there was no link between pet ownership and empathy in a group of children, a 2017 study of 1000 7- to 12-year-olds found that pet attachment of any kind encouraged compassion and positive attitudes toward animals, which promoted better well-being for both the child and the pet. Children with dogs scored the highest for pet attachment, and the study notes that "dogs may help children to regulate their emotions because they can trigger and respond to a child's attachment related behavior." And, of course, only one pet will happily play fetch with a toddler.

A version of this story originally ran in 2015.

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Bob Fugate
Inside the Pet Prosthetics Company That's Changing Animals' Lives
Bob Fugate
Bob Fugate

When Chi Chi the dog was found on the side of the road in South Korea, animal rescuers weren’t sure if she would survive. She had been badly abused and suffered severe blood flow loss to her legs, rendering them immobile. The normal course of action in that situation would have been euthanization, but Chi Chi made it clear that she wasn’t ready to give up. “I always say that her smile saved her,” Derrick Campana, founder of Animal OrthoCare, tells Mental Floss. “She was just so friendly and lovable that she got noticed.” The decision was made to amputate all four of her legs, and it wasn't long before a viral video telling Chi Chi's story caught the attention of a couple in Arizona. Shortly after moving to her new home in the U.S., Chi Chi was outfitted with prosthetics designed by Campana that allowed her to move around freely for the first time since she was rescued.

Campana and the work he does for disabled animals like Chi Chi were the focus of the first episode of Dodo Heroes, a new Animal Planet series that highlights inspiring stories of animal strength and survival. The prosthetics designer fell into the veterinary field by chance: He was working as a doctor specializing in prosthetics for people when a canine patient was brought in to his practice. The doctor the dog was supposed to see wasn’t in, so Campana decided to build an artificial limb for the pooch himself. “I got so much satisfaction and fulfillment out of it that I knew it was something I wanted to do forever,” he says. He launched Animal OrthoCare, his animal bracing and prosthetics company, one month later.

There aren’t many options out there for pet owners looking to provide comfortable, effective prosthetics to their disabled animals. A dog amputee might be fitted with a canine cart, while larger wild animals with missing or dysfunctional limbs are often put down. And when prosthetics are available, the choices are usually limited, sticking pets with something that can exacerbate their pain and discomfort.

Derrick Campana builds a custom leg brace for Jabu the elephant.
Derrick Campana builds a custom leg brace for Jabu the elephant.
Animal Planet

Animal OrthoCare is different: It’s the only company in the U.S. that offers custom animal braces, and it’s one of only a handful of custom animal orthotics companies on earth. Animals in need around the world can take advantage of its services. For most requests, Campana mails out a casting kit to the owner or veterinarian of the animal patient. After a cast is made of the patient’s limb, it’s mailed back to Animal OrthoCare’s shop in Virginia, where Campana and his team use it to build a custom prosthetic from medical-grade foam. It takes about a week on average before the final product is ready to ship to the customer's home, where they can attach it to their pet themselves using a hook-and-strap system that can be adjusted for maximum comfort.

In addition to being convenient, the treatment is also relatively affordable, with dog prosthetics starting at $750. Since founding Animal OrthoCare, Campana has helped roughly 20,000 animals walk again—and walk more comfortably.

Chi Chi the Golden Retriever and Jabu the elephant, the two patients featured in Campana's episode of Dodo Heroes, represent two of his biggest challenges to date. Chi Chi is a survivor of the South Korean dog meat trade, and she had been hung upside-down by her legs for so long that it cost her all four of her limbs. According to Campana, quadriplegic dogs are very rare, and dogs with four prosthetics are even rarer. By visiting Chi Chi in her home and adjusting the fit of her artificial limbs, he makes sure she can walk freely without doing any further damage to her body.

Jabu, a 31-year-old elephant living in Botswana, is another extreme example of the animals Campana gets to work with. After Jabu fell into a ditch and injured his leg, the caretakers at the wildlife preserve where he lives reached out to Animal OrthoCare for help. Campana says the leg brace he constructed for the 6-ton creature is likely the world’s first elephant brace. Without it, Jabu may not have survived even another minor injury. “A dog can have this type of injury and live a fine life, but for an animal like Jabu in the wild, it's life-threatening,” he says. “If you're lame out in the African bush, you're not going to live.”

Jabu the elephant.
Jabu the elephant.
Living With Elephants

Chi Chi and Jabu are two extraordinary cases, but the impact Derrick Campana had on their lives is typical of the work he does for animals on a regular basis. You can watch the full episode here.

Tune in to Dodo Heroes on Animal Planet on Saturdays at 9 p.m. ET.

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