You know the drill. You're having dinner when suddenly a black nose appears under the table between your legs. You tilt back and there are those eyes. Those eyes. If you're a savvy dog owner, you resist sliding down there — eating from the table is a bad habit you don't want to encourage. Plus, this is your food. It's people food. We don't eat animal food. Dogs have their own food, specially formulated for their dietary needs. Right?
Well, maybe not. A new study from researchers at the University of Illinois (U of I) finds that not only is human-grade food digestible for dogs, but it's actually more digestible than much dog food. The proof is in the pooing.
The study is an accepted manuscript for the peer-reviewed Oxford Academic Journal of Animal Science.
Four diets were tested
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The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The ingredients of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a pasta maker. The resulting pellets are sprayed with additional flavor and color.
For four weeks, researchers fed 12 beagles one of four diets:
- a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe
- a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe
- a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe
- another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.
The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts.
(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)
Senior author Kelly S. Swanson of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he says, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."
Tracking the effect of each diet
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The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.
It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.
Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."
Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.
"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in previous studies, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."
How did kibble take over canine diets?
Historically, dogs ate scraps left over by humans. It has only been since 1870, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn human-food waste into profit.
Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are overweight or obese, and certainly their diet is a factor.
We're not so special among animals after all. If something's healthy for us to eat—we're not looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.
Between the heartrending sad eyes when we leave and the explosion of happiness when we return, many (rightfully flattered) dog owners reasonably wonder what happens in-between. The physical evidence suggests nothing really bad happens—outside the occasional chewed slipper—but it's nonetheless clear our dogs would prefer not to be left behind.
A new study from researchers at the Universities of Pisa and Perugia, Italy, confirms that canines don't exhibit signs of extreme upset while we're away. However, the scientists found that dogs do have an easier time emotionally when we give them an affectionate, gentle petting before leaving.
The study is published in ScienceDirect.
The study
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The researchers conducted experiments with 10 healthy dogs between 1-11 years old and without unusual attachment issues. Six were spayed females and four were neutered males. The group was composed of seven mixed-breed dogs, one Labrador retriever, one Hovawart, and one Chihuahua.
The tests were conducted in an outdoor, fenced-in area and were videotaped for later analysis. Their owners walked their leashed dogs into the fenced area where they greeted a researcher, AKA Test Leader 1. A second researcher measured the dog's heartbeat using a phonendoscope and quickly departed.
Each dog was tested twice. In the first test, called the NGT ("No Gentle Touch") test, the owner and Test Leader 1 chatted for minute, essentially ignoring the dog. For the second, WGT ("With Gentle Touch") test, the owner petted the dog during the one-minute Test Leader 1 chat.
In both tests, after the brief chat, the owner handed the leash to Test Leader 1 and hid behind a shed for three minutes at a distance considered too far for the dog to pick up its owner's scent. The dog was free to move around the enclosure to the extent that the 1.5 meter leash allowed. The dogs spent a significant amount the time looking for their owner—in three minutes, they searched for between 84.5 and 87.5 seconds.
After the separation, Team Leader 1 called over the owner, and the leash was handed off. After 15 minutes of light activity, the dog's saliva was tested for the presence and level of the stress hormone cortisol.
Petted pet
All dogs participated in both tests, separately. Tests were spaced 5-9 days apart and took place at roughly the same times for consistency of cortisol levels.
The researchers found that when dogs had been petted they exhibited a more relaxed demeanor during the separation.
The canines' heart rates were tested before and after separation—they may have been elevated from the start from the car trip to the test site. After the NGT test, dogs' heart rates were unchanged by the separation. After the WGT test, dogs' heart rates actually went down, indicating the experiment left them more relaxed than they were when they arrived.
Cortisol levels were the same after both tests.
The study suggests it would be a good idea to develop the habit of building in a little extra departure time for your buddy each time you plan to leave home. Your dog will be happier for it.
We know that at some point long ago there were wild wolves who became companions for humans, and eventually evolved into dogs. The oldest verified dog remains, found in Germany, are from 15,000-16,000 years ago. Much of the story remains mysterious, though. Where it happened, for example: There are reports of dogs in ancient Siberia, in Europe, and the Near East. There are signs of pooches in the Americas some 10,00 years ago. Are all these dogs connected? And how did they become human companions in so many places and cultures?
A new study of ancient human and dog DNA, considered apart and together, published in the journal Science, fills in some of the missing pages in this long-running love story.
"Dogs are our oldest and closest animal partner. Using DNA from ancient dogs is showing us just how far back our shared history goes and will ultimately help us understand when and where this deep relationship began," says one of the study's contributors, Human Evolutionary Biologist Greger Larson of the University of Oxford in the UK.
DNA gets around
Assyrian dog relief
Credit: Wikimedia Commons
The research is the product of a collaboration between Larson and paleogenomicist Pontus Skoglund of the UK's Francis Crick Institute. Skoglund is an expert in canine evolution, working with teams at both institutions as well as the University of Vienna.
The researchers analyzed DNA from over 2,000 sets of canine skeletal remains, some of which dated back as far as 11,000 years. Working with ancient DNA from Siberia, Europe, and the Near East, the researchers were able to add 27 newly sequenced dog genomes to the previously sequenced five.
The researchers compared the canine DNA to the genomes of 17 human individuals who lived during the same time frames in search of common influences that might further establish their connection. Indeed, correspondences were seen that reflected the impacts of humans bringing their dogs along with them as they migrated around the world.
They found that Swedish farmers and their dogs are both descended from canines of the Near East, suggesting that man and dog followed the development of agriculture together through Europe. On the other hand, German farmers 7,000 years ago came from the Near East, but their dogs didn't.
Lineages intersect
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Based on their analysis, the scientists assert that by 11,000 years ago, just after the Ice age, there were already five distinct families (or lineages) of dogs, so the German remains were no outlier. These lineages eventually developed into later lines.
Some of this occurred through interbreeding with other dogs and also through mating with their wild wolf cousins. Comparisons between ancient dog and wolf DNA revealed a surprise: Wolves picked up DNA from dogs, but, at least judging by the remains available, there was little or no gene flow back in the other direction. Larson suggests to Science that the evidence may have been tampered with, so to speak — if a dog started behaving like a wolf, its human may well have simply gotten rid of it.
Anders Bergström is the lead author of the study, and he points out a mystery it reveals: "If we look back more than four or five thousand years ago, we can see that Europe was a very diverse place when it came to dogs. Although the European dogs we see today come in such an extraordinary array of shapes and forms, genetically they derive from only a very narrow subset of the diversity that used to exist." Why — and how — one line of dogs so dominated early Europe as to wipe out other lineages remains a mystery. The researchers found no human development that mirrors, or could explain, this event.
A dog's life
It's fun to realize that ancient dog lineages persist to this day. It turns out Chihuahuas have traces of ancient American dogs, and Huskies bear traces of their cold-weather ancestors. Skoglund tells Science that on any given day in a modern dog park, you may be looking at lineages that date back 11,000 years.
It's likely that subsequent research will reveal even more. Says co-author and University of Vienna group leader Ron Pinhasi, "Just as ancient DNA has revolutionized the study of our own ancestors, it's now starting to do the same for dogs and other domesticated animals. Studying our animal companions adds another layer to our understanding of human history."
It's been known for a while that some animals — migratory birds, mole rats, and lobsters among them — use the Earth's magnetic fields to navigate. There's even some evidence suggesting we do, too. In 2013, zoologist Hynek Burda found that dogs tend to poop and pee along a north-south axis, although at least some dogs (including our own Lulu) don't agree. New research indicates that dogs also orient themselves to the Earth's magnetic field as they invent shortcuts to get from place to place.
The research comes from Kateřina Benediktová of the Czech University of Life Sciences Prague — Burda is her PhD adviser — and is published in eLife.
Guessing the secrets of canine navigators
That dogs have excellent navigational talents is nothing new. The study recalls "messenger dogs" that were relied on during World War I to ferry sensitive communiqués back and forth across battle lines. In addition, of course, hunting dogs, or "scent hounds," have long exhibited the ability to return to their owners' positions, and previous studies have shown that they often devise new return routes, as opposed to simply retracing their steps. How they do this has been a bit mysterious, as the study notes: "Dogs often homed using novel routes and/or shortcuts, ruling out route reversal strategies, and making olfactory tracking and visual piloting unlikely."
In trying to figure out how dogs do what they do, researchers have divided their methods into three possible modes:
- tracking — following their own scent trail back to their point of origin
- scouting — searching for a new, shorter way back to their point of origin
- visual piloting — using landmarks to find their way back
Benediktová's research began when she put video cameras and GPS trackers on four dogs, took them out into the forest, and set them loose. As might be expected, they took off in pursuit of some interesting scent. All of the dogs eventually returned. She mapped the collected GPS data, seeing runs of both tracking and scouting.
However, when she showed her maps to Burda, he noticed something else. Just before scouting their way back, the dogs did something odd: They ran for roughly 20 meters along a precise north-south axis, as if orienting themselves, before returning to Benediktová. Without some form of magnetic sensitivity, this would not be possible.
Image source: Benediktová, et al
Testing the theory
A sample of four dogs is hardly definitive, so student and advisor developed a larger study involving 27 dogs who were taken on several hundred scouting trips over the course of three years. The dogs were typically taken to locales with which they had no familiarity, and the researchers avoided tipping off the canines with any navigational clues including the avoidance of situations in which wind could carry their scent toward the dogs. The researchers also hid after releasing their charges to make sure they weren't visible to the pooches.
In the end, the researchers documented 223 scouting runs in which the dogs averaged a return to their points of origin of about 1.1 kilometers (around 0.7 miles).
In 170 of these runs, the dogs did indeed repeat the smaller sample's behavior, running about 20 meters along a north-south axis. Just as intriguingly, it was these dogs who found the fastest, most direct route back. "I'm really quite impressed with the data," biologist Catherine Lohmann of the University of North Carolina, Chapel Hill, who was not involved in the study, tells Science.
Burda considers the dogs' seeming reliance on their north-south jog to be pretty convincing: "It's the most plausible explanation."
Proving the theory
Commenting on the research, dog behaviorist Adam Miklósi at Eötvös Loránd University tells Science, "The problem is that in order to 100% prove the magnetic sense, or any sense, you have to exclude all the others."
Given the difficulties of doing that, Benediktová and Burda intend to test their hypothesis from the other direction, seeing if they can confuse dogs' magnetnoreception by placing magnets on their collars and repeating the tests — if they no longer do their little north-south jog, a reliance on the Earth's magnetic field would look even more likely.
Admit it, you treat your dog like it's a person and act accordingly. It's kind of okay though, tons of people do.
Researchers with the Interdisciplinary Center of the Baruch Ivcher School of Psychology asked 104 dog owners to keep a journal for 21 days. The test subjects rated how much they agreed with statements about their interactions with their pet such as "When I interacted with my dog, I tried to show it that I really care for it" or "When I interacted with my dog, I tried to let it feel free to be its true self." They also responded to questions of how they were feeling, and if they supposed their dogs cared about them.
As predicted, owners who gave their dogs more support reported higher levels of well-being, felt closer to their pets, and noted less psychological distress. The effect was more substantial than the benefits gained from receiving support from pets, suggesting that giving support satisfies a need by itself.
The dogs involved in the study could not be reached for comment but are assumed to have enjoyed the attention.
Self-Determination Theory
The authors interpreted these findings in the light of Self-Determination Theory, or SDT. A theory of human motivation that focuses on innate drives and needs, it centers around the idea that humans function well when our internal motivations are satisfied and less so when they are not. The key motivations are:
- Autonomy, defined as a need to be a causal agent.
- Competence, defined as the need to experience mastery.
- Relatedness, defined as the need to interact and connect with others as well as the need to experience caring.
One possible explanation of the pet effect observed here is that owners are anthropomorphizing their dogs and allowing their owners to perceive tending to a dog's needs as similar to tending to another person's needs. In particular, this is satisfying the need for Relatedness. Whether dogs actually have the same need to connect with others or to be supported so it can "feel free to be its true self" as humans do remains unknown.
In any case, it does appear that you can satisfy your need to care for something by trying to make your pet happy. Exactly how far this effect can be pushed and if it still works if people aren't anthropomorphizing their pets are areas for future study.
But I don’t own pets, so how does this apply to me?
The ideas behind SDT can be applied in many situations, not only ones involving pets. A variety of other studies have shown that providing care for others can improve your well-being, but have focused on what happens when humans tend to other humans.
Science has confirmed what many pet owners always knew, taking care of your fur-covered friend is often more of a joy than a chore. This study points to new ways to improve your well-being by interacting with both humans and animals to make everybody feel a little better.
Now, if you'll excuse me, I'm going to play with a cat.
