For the past couple of decades researchers have been looking at the role that pets, especially dogs, have to play in rates of allergies in children. Many have found that, what is being termed the hygiene hypothesis, is indeed correct, meaning that a little dirt early in life helps to stave allergic diseases, including obesity.

A new study by Anita Kozyrskyj a pediatric epidemiologist of the University of Alberta in Edmonton, Canada, found further evidence of this dog-human linkage and how this lessens the development of everything from obesity to asthma.

Starting in 2013 she wondered if she could pinpoint what and how this might be happening. Her team collected fecal samples from 4-month-old infants in the Canadian Healthy Infant Longitudinal Development (CHILD) pilot study. Of the 24 respondent infants, 15 lived in house with at least a dog or cat.

What they found was that within the households with pets, the children had a higher diversity of microbes in their guts. Microbes, as we now know, can be a good thing for our gut microbiome and immune systems actually develop alongside our gut’s “germs.”  Meaning that if babies grow in a more “sterile” pet-free environment, they would be more unprepared to “fight” germs as they grow up.

Kozyrskyj noted, "The abundance of these two bacteria (Firmicutes microbes) were increased twofold when there was a pet in the house," and added that the pet exposure was shown to affect the gut microbiome indirectly—from dog to mother to unborn baby—during pregnancy as well as during the first three months of the baby's life.

Also interestingly, this study suggested that the presence of pets in the house reduced the likelihood of the transmission of vaginal GBS (group B Strep) during birth, which causes pneumonia in newborns and is prevented by giving mothers antibiotics during delivery.

Kozyrskyj’s study confirms and expands on the work that many other researchers have shown that some “dirt” can be beneficial and help to ward off disease. Including one, conducted at Kuopio University Hospital in Finland in 2012, that concentrated on infants during their first year, and investigated the effect of contact with dogs on the “frequency of respiratory symptoms and infections.” Information about the length of time a dog spent indoors was also gathered, and turned out to be one of the key indicators.

The results were eye-opening. Children with dogs at home were healthier overall, had fewer infectious respiratory problems, fewer ear infections and were less likely to require antibiotics. Researchers considered these results supportive of the theory that children who live with dogs during their early years have better resistance throughout childhood. They also found that the effect was greater if the dog spent fewer than six hours inside, possibly because the longer dogs are outdoors, the more dirt they bring inside with them. The more dirt, the more “bacterial diversity.” This diversity is thought to have a protective influence by helping the child’s immune system to mature — that is, respond more effectively to infectious agents.

Then a 2013 study conducted by the University of California, San Francisco, and the University of Michigan, Ann Arbor, found that living with dogs may prevent children from developing asthma. Mice fed a solution containing dust from homes with dogs developed a resistance to respiratory syncytial virus (RSV), a childhood airway infectious agent. RSV, which is common in infants, is linked to a higher risk of childhood asthma. According to Dr. Susan Lynch of the study team, “Exposing the gastrointestinal tract to pet dust and other microbes early in life prepares it to respond appropriately to a variety of invaders. But since our modern lifestyles involve living in immaculate houses, our immune systems often overreact instead.” Early childhood is a critical period for developing protection against allergies and asthma, and exposure to pets can help.

The idea that our microorganisms may to some extent be collectively beneficial is intriguing. People and dogs have been exchanging microbes for at least 30,000 years, since the first little cave girl kissed the first proto-dog puppy smack on the muzzle. That’s a long history of sharing. It’s possible that our microorganisms are at least symbiotic, and perhaps even played a role in the dramatic domestication of the dog. 

As was reported in Nature: Researchers suspect that our long association with canines means that human and dog microbiomes may have developed in tandem. The microbiome of a baby growing up without a dog (and of a puppy growing up without a human) is, in a sense, incomplete. “All of the people alive today probably had ancestors who lived in tribes that hunted with dogs,” says Jack Gilbert, director of the Microbiome Center at the University of Chicago in Illinois.”

Since 2013, Canadian researcher, Kozyrskyj has expanded her pilot study from 24 to 746 infants, around half of whom were living in households with pets. Her team then compared the babies' microbial communities.

The results were basically the same, microbial life flourished in the infants living with pets. And not only that but the “team was now able to show that babies from families with pets (70% of which were dogs) had higher levels of two types of Firmicutes microbes — Ruminococcus and Oscillospira, which have been associated with a lower risk of allergic disease and leanness, respectively.

“Pet exposure can reduce allergic disease and obesity” later in life, added Hein Min Tun, a veterinarian and microbial epidemiologist and a member of Kozyrskyj’s research team.

And while it might be too soon to predict how this finding will play out in the future, they don’t rule out the concept of a “dog in a pill” as a preventive tool for allergies and obesity. Or, as we much rather see, “dog as the pill.”

Bark has long admired Amy Sutherland’s commitment to animals, as well as her smart and engaging writing style. In her new book, Rescuing Penny Jane, both are on display as she tackles the issue of homeless—or, as she says, human-less—dogs, and gives readers an insider’s view of the many challenges shelters face and how they respond to them. Bark editor Claudia Kawczynska recently caught up with Sutherland for a quick one-on-one.

Bark: What advice would you give people who want to volunteer at a shelter or foster a dog?

Amy Sutherland: I have found volunteering and fostering each to be enormously rewarding, but I’ve also found that you need to have (or develop) a thick skin. As a foster, it can be wrenching to send a dog to another home, even though that was your goal. And as a volunteer, some of the dogs’ stories or conditions can be heartbreaking. If you volunteer in a shelter that euthanizes dogs for medical, behavioral or other reasons, you will also have to contend with that. The dogs—helping them—keep me going.

I’d also suggest exploring various shelters and rescues, private nonprofits and municipals in your area to find one that makes the most sense for you. Some might be more flexible about how often you need to volunteer, for example. Keep in mind that municipal shelters often are the most in need of volunteers.

A memoir by Patricia McConnell, one of the world’s leading certified applied animal behaviorists and a pro in working with aggressive and fearful dogs, is the second of the two new arrivals. The Education of Will: A Mutual Memoir of a Woman and Her Dog (Atria) is quite unlike her previous work. While her astute, hawk-eye attention to canine behavioral matters is found in abundance, we also learn more about the author herself.

The Education of Will runs on parallel tracks. On one track is her Border Collie, Will, who presents McConnell with a whole host of behavioral and health-related challenges. It is difficult to comprehend just how misaligned this little guy was, even as a very young pup.

As she tells us, when she decided it was time for another Border Collie, McConnell did all the right things: she went to a reputable breeder; she knew both parent dogs; and, since she’d had other working Border Collies, she definitely understood the breed. Despite this, she still wound up with a dog whose unpredictable, furious outbursts “shook her to her core.” (This is in itself a valuable lesson for those who might be skeptical about adopting a shelter dog because of the possibility of behavioral problems; as Will demonstrated, opting for a well-bred puppy is no guarantee you’ll avoid them.)

The book’s other track follows the human end of the leash. While working with Will, McConnell realized that she needed to come to terms with her own fears, and the ways earlier traumas had informed her behavior—that in order to heal her fearful, reactive dog, she had to heal herself as well.

What has always set McConnell apart from others in her field is her ability to point out the fascinating parallels between canine behaviors and our own, including the cognitive and emotional lives of both species. In this book, she dives even deeper into such comparisons. For me, her insights into her troubled Border Collie’s behavior (as well as that of other dogs she’s treated) are the book’s most compelling aspect.

McConnell offers the case of Aladdin as an example of how a dog’s aggression can be set off by triggers. Aladdin’s sunny disposition would change in an instant once she put on sunglasses. As she noted, “To Aladdin, I had morphed instantly from a relaxed, benevolent acquaintance into a … potentially dangerous one. Aladdin was just going to get me first, before I could get him.” This was a relatively straightforward case; once she discovered the trigger, she could devise a treatment plan. Will’s issues, unfortunately, were not that simple.

This book speak eloquently on the benefits of opening your heart to dogs, and reclaiming lives in the process.

Any time Alexandra Horowitz releases a new book is cause for celebration here at Bark. We’ve been fans since her 2009 hit, Inside of a Dog, and have continued to follow her work as she uncovers new insights into our co-pilots’ internal lives and external behaviors.

In addition to teaching psychology, canine cognition and creative non-fiction at Barnard College, Columbia University, she also leads the college’s Dog Cognition Lab.

Her new book, Being a Dog, delves deeply into the primacy of dogs’ sense of smell, and we talk with her about what she found.

Bark: Has anyone studied why some dogs are better at smelling than others —is it genetic or is it drive?

Alexandra Horowitz: Everything I’ve seen points to drive being the major indicator of whether a dog will be good as a detection dog: drive to find the odor, to keep working when frustrated, to get to the reward (like a game with a tug toy) at the episode’s end.

This is not to say that breed is irrelevant: some breeds are naturally more driven to pursue an odor relentlessly, or are driven to do whatever it takes to get a game of toss with a tennis ball. And some dogs—like Bloodhounds and Beagles—have more olfactory cells in their noses and more equipment around their faces (long ears, drooly jowls) to help bring odors up the nose. They may smell odors at lower levels.

Curiously, though, the notion that certain breeds are inevitably better at detection work than others hasn’t been borne out. It’s tradition more than science.

B: I was once told by a woman who handles tracking Coon Hounds that dogs can show a preference for how they scent; talking about the same breed, she said some sniff the ground, while others prefer sniffing the air. Have you observed individual differences in the same breed in your research?

AH: Absolutely. Different dogs have different sniffing tactics; “on the air” or “on the ground” are the two ways dogs try to pursue a scent. Often, though, these are distinguished by task, not by dog—that is, if a dog is tracking a distant (old) scent, on the ground makes more sense; the odor is probably no longer in the air. But a dog trying to locate someone/something who has recently passed by will be air-scenting.

B: Can adult dogs can identify their littermates or their mother by smell?

AH: In theory, this would be trivially easy for dogs. All dogs have their own “signature scents” (as do we, to dogs), so there would be no trouble distinguishing dogs of one’s litter from other dogs. Now, the question of whether an adult dog who has been separated for years from her littermates/family can recognize them is a different question: it’s more about memory than about perceptual ability. Memory is fallible in humans, and it is fallible in dogs. We forget. So it’s quite possible that, even having known one’s family by scent, it would be later forgotten. (But there is also good reason to believe that a trace would remain—that distant memory one cannot quite place.)

B: While you note in your new book that puppies at the Working Dog Center at the University of Pennsylvania aren’t formally trained until a certain age, they do receive some kind of training, right?

AH: Yes, they are being “trained” to some degree: I think Dr. Otto and the Penn Working Dog Center trainers would agree when I say they are being trained to be good general-purpose working dogs. As I describe in my book, I saw dogs being put through their paces in lots of different (what were to them) games: find the missing person, find the hidden scent. They are being exposed to unusual sounds and environments and getting acclimated to them. They are learning the skills of detecting something, working with someone, and loving it. And they do.

B: Do working dogs get nose fatigue— do they reach a point at which they can no longer reliably follow a scent? If so, what do the pros do to work around that?

AH: The phenomenon of the nose no longer noticing an odor—adaptation —happens to us within minutes. Walk into a coffee shop, take in its familiar odors and a few minutes later, you might smell … almost nothing. The receptor cells in the nose that noticed the odor simply stopped responding after continued exposure.

The cells in the dog’s nose work similarly, but any dog employed as a detection dog is doing something different. Because they continue to sniff different areas of the odor “scene,” their noses won’t turn off to the smell. Tracking dogs are also known to simply lift their noses from the ground once in a while and sniff the air, as though to clear their noses.

On the other hand, working dogs certainly get fatigued from too much stimulation and too much exertion. Handlers know their dogs and will read their dogs’ responses to know when they need a break.

B: In the book K9 Scent Training by Resi Gerritsen and Ruud Haak (leading specialists in identification, tracking and detection-dogs), I read that female dogs are better at smelling than males. Did this also come up in your research? Any idea if the same can be said for our species?

AH: Gerritsen and Haak are great resources on detection-dog training and skills. I suspect their assessment comes directly from their own and other trainers’ experience with dogs. I don’t doubt it, though I don’t believe that the question has been formally tested. Interestingly, women are often said to be “better smellers” than men, and research does bear this out (on average, of course).

B: I’m quite curious about the canine visual sense vis-à-vis their olfactory sense, especially for dogs of the sporting breed. When our Wirehaired Pointer is out in the field, she seems to rely primarily on her sense of smell; sometimes a rabbit’s been sitting just a few feet from her, but she doesn’t see it, or even seem to smell it. Is it “I can’t smell it so I don’t see it”?

AH: As with us, dogs’ senses work together. Only for dogs, olfaction takes priority. From that point of view, you can imagine how vision might aid smelling: if a dog detects an odor on the breeze, she can then look up and try to locate, with her eyes, the source of that odor (and then head toward it for closer sniffing!). When I watched the dogs at the Penn Working Dog Center do a “person search” for people hidden in large PVC barrels in a large field, the dogs used vision to guide them while smelling: first, they followed their eyes to head toward the barrels, then followed their noses to identify which one held a person.

A dog who is sniffing in the grass to a hidden ball (or rabbit) that is perfectly “visible” to someone else nearby is simply using olfaction first. By sniffing in the whole area around the hidden object, she creates an on-the-fl y map of where the object is; the closer she gets, the stronger the odor is. Sometimes, dogs rely on that much longer than we would expect before bringing fuller attention to what they see to aid their search.

B: I’m trying to train one of my dogs, Charlie, to find the poop of his housemate Kit while we’re out in the park; he’s actually pretty good at it. I started doing this after I noticed that he likes to pee on her fresh poop, and only on hers. How would you recommend I boost his proficiency level? And why the peeing on it?

AH: “Find poop!” Great game. And lots of dogs would be pretty good at it. Since Charlie started doing this behavior on his own, clearly little shaping was needed. The only task is pairing it with a request (like “find poop”) and making him aware that what he’s doing—which to him is “following that interesting smell”—is something that’s also valuable to you, so he’ll do it whenever you ask. If he’s not doing it reliably, then he doesn’t see its value to you. Better rewards! More reliable rewards! (But you and every good behavior reader know that.) And, taking a cue from working-dog handlers, you could pair an “alert” behavior—sitting, barking and so forth—so that he tells you when he’s found it.

What I learned from Sam Wasser, who trains dogs to find wildlife scat, is that what’s often difficult in training in the field (and you’re always “in the field”!) is to know yourself if the dog has alerted on the right scat. Once they are confident of their dogs’ alert, and don’t accept partial alerts, handlers can reward only for the correct scat.

As for his peeing on the poo, that’s a question I don’t think science has directly tackled. But we know that marking isn’t territorial in dogs; it seems to be information-leaving. It could be that a nice pile of stinky poo is a good place to leave your own mark.

B: Besides enrolling our dogs in nosework classes, what do you recommend that we do to tap into their world of smell and enrich their lives?

AH: Let them smell. If you live with a dog, start thinking about what the world is like from an olfactory point of view. Let them smell you (you are your scent, to your dog), let them smell each other (that’s how they find out who it is), and let them smell the world. Take walks for smelling (not just for peeing, or for exercise). The pleasure that comes from watching a dog snuffling down a path, nose to the ground and nose in the air, guided by nothing more than the filaments of odors that come his way, is to me unmatched.