Good Dog: Studies & Research
The classic self-recognition test gets a makeover for dogs, using smell not sight
September 6 2017
Dogs know individuals. Your dog knows I am not you and you are not me. Your dog knows that Rudy down the block is exceptional at playing, but Spot is not.
If dogs can recognize individuals, and your dog is an individual, might your dog know himself? As an individual? Does he have a sense of “me-ness”?
Alexandra Horowitz wants to know what it’s like to be a dog. Even her Twitter bio is dog-aware: “dogs sniff me; I sniff them back.” Her popular writing and research—at Barnard College’s Dog Cognition Lab in NYC—explore the unique experiences of the dog. Her recent publication in Behavioural Processes tackles the hefty question of their self-recognition.
But first, my teeth.
It was probably a good two hours post-lunch before a bathroom mirror informed me that I had a big piece of green gunk in my teeth. I was able to make this find—accompanied by “#$@&%*! Why didn’t anyone tell me?”—because I know mirrors reflect me, Julie. Faced with a mirror, we see ourselves: our constants (yup, my eyes are still brown), and our changes (#$@&%*! that pimple wasn’t there yesterday). You and I haven’t always done this. An understanding of self-in-the-mirror appears by age two.
Since the 1970s, researchers have used the mirror as a tool to investigate self-recognition in non-human animals. The main components of the mirror-self recognition test are a mirror and an individual who has covertly been marked in some way. In the original mirror test, chimpanzees—who had secretly been marked on the face with red odorless dye—were found to use the mirror to examine the mark. Something about them had changed. They would touch the mark on their face, in the same way you might touch a newly appearing pimple on your face. Not reaching toward the mirror, but instead using the mirror to refer back to themselves. Since then, the mirror test has panned out in a number of species like chimpanzees, dolphins, Asian elephants, and European magpies.
But dogs aren’t on this list. From personal experience or entertaining YouTube videos, you know that young dogs, or dogs unfamiliar with mirrors, often treat mirrors as another dog. Over time, dogs typically come to ignore mirrors. Studies find some dogs use mirrors to gather information or solve a problem—recognizing it as a tool to help see behind themselves or locate hidden food.
If dogs don’t “pass” the mirror test, is this the end of their self-recognition story? Not so fast. Maybe the traditional mirror test isn’t the most fitting medium for questions-of-the-self in dogs.
After all, dogs are beings of smell, not sight. From quivering nostrils to sizable brain regions dedicated to olfaction, dogs are equipped to take in and process smells. Humans have harnessed this skill and taught working dogs to notice smells we designate important, like the presence of cancer or narcotics.
And then there's pee. Dogs find certain smells, like dog urine, intrinsically interesting. Dogs both leave, and investigate, urine deposits. It is pee that leads countless dogs around the world to pull humans this way and that when out on a walk (ok fine, dropped food’s also a high priority). With this in mind, Marc Bekoff, professor emeritus of Ecology and Evolutionary Biology at the University of Colorado, proposed researchers turn to urine for questions of “self” and “other” in dogs.
Bekoff’s “yellow snow” study, published in 2001, explored the topic of “me” / “my” and “you” / “your.” His field experiment was as hands-on as it sounds. Over the course of five winters, when out walking his dog Jethro, Bekoff moved urine-soaked snow to see how Jethro behaved when encountering his own pee versus that of other dogs. Jethro performed as expected, sniffing other dogs’ urine more than his own. Jethro, Bekoff suggested, “clearly had some sense of ‘self’: a sense of ‘mine-ness’ but not necessarily of ‘I-ness’.”
Alexandra Horowitz’s new study takes into account the main features of the mirror test as well as the “yellow snow” study. She devised a test explicitly suited for dogs—an olfactory mirror test. Think about it: In the visual mirror test, individuals attend to something visually different about their appearance. An olfactory mirror test, Horowitz explains, asks whether dogs attend to something changed about their own smell when their “smell image” has been changed by the addition of a new odor. This new odor, of course, aims to be equivalent to the mark, in mirror terms.
Over two experiments, Horowitz measured how long companion dogs sniffed different odor samples simultaneously presented to them in canisters. More sniffing, you can imagine, is akin to more interest. Given my interest in dog attention to chemical information—yes, I mean pee sniffing— you can imagine I was elated to participate in this study and present canisters to 36 wonderful dogs in Experiment 1. Horowitz found that dogs spent more time investigating their own urine that had been marked (modified with the addition of an odor), compared to their urine alone. “Me different,” you might conclude from the dog’s behavior.
Olfactory investigation coded when dog nose within 10 cm of canister. Credit: Horowitz 2017. Figure 3
Or maybe there’s another explanation. Dogs are neophilic, known for their interest in new things. Could it be that dogs spent more time sniffing their marked urine because they were interested in the new smell, independent of their own smell? Dog behavior better translated as: familiar smell over here = boring, but familiar smell mixed with new smell = interesting?
With this possibility in mind, dogs also investigated their own urine marked versus the mark substance itself. These trials eliminated novelty as a factor because both canisters contained the novel odor. In these trials, dogs did not differ in the amount of time spent sniffing each sample. Ruh roh. Where does that leave us?
This is where the scientific process shines. Could it be that the selectedmark itself affected the results? In the classic mirror studies, the mark aims to be inherently neutral, not highly unique or interesting on its own—an ink mark, a piece of tape, a sticker. Ho hum. The mark in Experiment 1 of the olfactory mirror test was a cancerous tissue sample from a dog, an unfamiliar odor (adding novelty) that untrained dogs are said, anecdotally, to notice. It’s possible the cancer cells were too interesting and novel, thus deviating from the neutral mark used in classic mirror tests. In fact, a number of dogs encountering canisters with the mark had pronounced “disgust” responses, highlighting that the selected mark might not have been so neutral.
Horowitz tried a different mark. Experiment 2 tested 12 dogs with a more neutral mark—anise essential oil from the sport of Nose work. In these trials, dogs replicated the main findings, investigating their own urine that had been marked more than their urine alone. But this time, dogs were also more interested in their marked urine than the mark alone, making it less likely that the mark’s novelty explained the results. Horowitz reflects, “This suggests that the longer investigation time is not tied to an interest in the mark, per se, but rather an interest in the mark when it appears in combination with or on the dog's own odour.”
With a new olfactory approach in place, studies will surely continue to refine and tease out the meaning behind dog interest in familiar—yet modified—scents. Inquiries like the olfactory mirror test put the microphone in the paws of the dog. If they could comment, I'd imagine they'd say, “Thank you for considering our pee! After all, pee means so much to us!”
This story was originally published by Scientific American. Reprinted with permission.
News: Guest Posts
EEG study suggests sleep enhances learning
September 2 2017
A Harvard Medical School professor recently rocked the Internet: “Since dogs are generally extremely attached to their human owners, it’s likely your dog is dreaming of your face, your smell and of pleasing or annoying you,” psychologist Deirdre Barrett told People magazine.
And then hearts everywhere exploded.
Barrett’s sleep research focuses on humans, while an interest in evolutionary psychology helps her consider the sleep of non-human mammals. Both have similar sleep cycles, she notes, which could suggest parallels in sleep quality or experience.
But an open access study in Scientific Reports out recently moves away from extrapolation and toward hard data. Researchers in Hungary have devised a way to non-invasively peer into the sleeping dog’s brain to explore the content and function of their sleep.
Sleep in dogs is good for a number of things, including, but not limited to cuteness, cuteness, and more cuteness. But you’ve also probably heard that sleep is good for memory. Before a big test we’re often told, “Get a good night’s rest,” which is actually shorthand for—give memory consolidation a chance. “Memory consolidation” is the process where your brain pulls together pieces of information and packages them into memories that can be used in the future.
Memory is also important for dogs. Working dogs need to learn—and retain—a wide variety of job-specific skills, and companion dogs often learn basic skills to successfully live alongside humans. When a dog learns something new, can sleep help the dog perform those skills better? Should training sessions incorporate naptime?
Anna Kis of the Hungarian Academy of Sciences and colleagues—including members of the well-known Family Dog Project—set out to explore the relationship between sleep and memory in companion dogs. Their study involved two experiments: the first gave dogs a learning task and then peered into their sleep via non-invasive electroencephalogram (EEG)—a test that detects brain electrical activity using small electrodes attached to the scalp. The second experiment explored whether different type of post-learning activities (such as sleep) affect memory consolidation, both in the short- and long-term. All experiments were performed with consenting companion dogs and their helpful owners.
First up, the sleep study, also known as polysomnography if you want to be fancy about it. Fifteen companion dogs participated in both a learning and a non-learning condition. The experimenters taught the dogs the commands for “sit” and “lie down” in a foreign language (English). As you’d expect, no learning took place in the non-learning condition—dogs simply practiced the “sit” and “lie down” commands that they already knew in Hungarian. Nothing new. Old hat. (Most dogs don’t wear hats. Old collar?)
For the critical phase of the experiment, dogs went to sleep (gosh I love science). Dog snoozing-related brain activity was then monitored over the next three hours. Afterwards, dogs in the learning condition were retested on “sit” and “lie down” in English to determine whether sleep helped the dogs process what they had learned.
Recording setup. Credit: Anna Kis
Not only did the sleep affect dogs’ learning, the learning affected dogs’ sleep. Dogs did better responding to “sit” and “lie down” in English after taking a snooze. But even before the dogs in the learning condition were retested, two notable wave patterns stood out in the EEG spectrum in the non-REM phase (the dreamless part of sleep). There was an increase of delta power, similar to what is found in humans, and a decrease in alpha activity, which could suggest “an increase in sleep depth after learning.”
These two findings are related. Dogs learned a task, which alters their brain activity during sleep, then they performed better on the task. “This suggests that the newly acquired information is re-processed and consolidated during sleep,” Kis explained over email. More specifically, the correlation between the post-sleep improvement in performance and certain EEG patterns “is the strongest indicator that the changes in sleep EEG we see after learning are functionally related to memory consolidation,” added Kis.
Neat. Taking a snooze can improve subsequent performance (at least for this type of command learning task). But how do we make things stick? Is sleep more or less effective than other strategies for retaining information? A second behavioral experiment investigated the effect of different post-learning activities (including sleep) on subsequent memory.
Fifty-three new companion dogs learned “sit” and “lie down” to new words (again, English). Dogs were then put in one of four different post-learning groups, spending the next hour either sleeping, walking, learning more (learning new behaviors via the luring training method), or eating from and playing with a Kong dog toy. When the hour was up, dogs were retested on the English commands they’d just learned.*
The type of post-learning activity seemed to affect dog performance in the short term, but not exactly as the researchers had expected. In the short term, both sleeping and walking improved subsequent performance, while more learning and Kong play did not.
On the other hand, when dogs came back a week later, presumably after many sleeps, dogs in the sleep, walk, and Kong play conditions showed marked improvement with the English commands. Dogs who had done more learning did not improve.
Values >0 indicate a performance improvement at the given occasion, while values <0 indicate a decreased performance. Figure 3 Credit: Kis et al. 2017
Dog lovers often think about learning and obedience in terms of dogs doing it “right” or “wrong.” Factors surrounding learning, this study reminds, can affect memory consolidation and later performance.
Kis recommends: “Learning a new command should be followed by an activity that does not interfere with this new memory trace (e.g. sleeping, walking, playing–but not learning other things) in order to achieve the highest subsequent performance in the long run.”
At the same time, Kis noted that dogs in the sleeping condition might have performed even better if the nap extended beyond an hour (possibly for memory consolidation to fully take place), or if, after waking up, the dogs had a few more minutes to shake off their sleepiness before performing the tasks again. Human-sleep scientists refer to this latter phenomenon of decreased cognitive performance in the few minutes after waking up as “sleep inertia.” Don’t pretend you’ve never woken up, walked to the bathroom, and tried to brush your teeth with your comb. Since no sleep inertia interval has been established for dogs, Kis says, they can’t rule out the possibility that the dogs were still sleep zombies when they were retested.
Non-invasive studies of dogs and sleep are new. We haven’t yet studied whether your dog is dreaming of your face or your glorious smell, but if you care about learning in dogs, this study suggests you give sleep a chance.
-- -- --
* Maybe you’re wondering why there wasn’t a condition after learning where dogs simply rested—rather than slept—and then had their memory tested. This ‘resting’ awake condition is typically found in human memory consolidation studies because it’s the closest match to the ‘sleep’ condition. But this condition was not included for dogs, the researchers explain, “as preventing dogs from falling asleep while requested to stay in a laying position for one hour would presumably induce stress in the animals. Stress is known to have an impact on memory, and also raises animal welfare issues, thus we decided to avoid such a condition.”
This story was originally published by Scientific American. Reprinted with permission.
Good Dog: Studies & Research
Studies on dogs following gestures.
February 24 2017
AT TWO WEDDINGS, darling ring bearers paraded down the aisle proudly holding the prized objects. They couldn’t have been more than six. When they suddenly stopped—as six-year-olds tend to do—to look at something on the ground, guests leaned into the aisle and pointed toward the beaming faces ahead. Smiles filled the crowd as they continued on their way.
At one wedding, the ring bearer was a little boy, and at the other, a dog.
If we’ve spent any time with companion dogs, we aren’t surprised when a dog stops to check out the ground. It also shouldn’t surprise us that a dog might go where we point. Pointing is about social communication, and it often feels like dogs are right there with us, sometimes even more than members of our own species.
In the last 20 years, dogs’ attention to our communicative gestures—particularly this thing we do with our arm and finger—has attracted enormous attention from researchers around the globe. In fact, the pointing gesture is so fundamental that seemingly no article on the canine mind is complete without a sentence such as “dogs read our gestures, like pointing, more flexibly than any other animal” (New York Times), or—more boldly in Time—“While chimps and even wolves lack an innate ability to understand what pointing means, dogs come by the knowledge naturally.”
These statements tend to produce any number of reactions in dog owners, from “Obviously,” sometimes accompanied with a side of, “Why do they bother to do this research anyway?” to the flip side: “My dog doesn’t do that … what are they talking about?” Or even the more nihilistic view: “Sure they do, but who cares?”
Here’s why we care: this one little gesture, in all its complexity, could be a core feature of the intimate bond we share with dogs.
Since the late 1990s, researchers have tried to uncover why and how dogs pick up on our cues. Initially, key questions focused on whether their ability to follow the pointing gesture arose from our long-standing co-evolutionary history or, alternatively, if they learned the behavior over the course of their individual lives.
Pointing Is About Us
Pointing is something we humans do as part of our social communication, and it is useful only because we all agree on how it should be interpreted. Imagine if your point were perceived as, “Hey! Check out my fingertip. No dirt under my nail. Wonderful, huh?” Not exactly useful for communication. Fortunately, we understand that pointing creates a shared experience beyond our fingertips; pointing draws someone’s attention past our outstretched index finger to something out there in the world.
This cooperative gesture serves us well. Yelling, “Look out!” is only somewhat informative, but yelling, “Look out!” and pointing can help a fellow human locate and respond to a Frisbee sailing in at head level or Godzilla rampaging down Fifth Avenue. Communication achieved.
Despite our mothers’ reminders that pointing is rude, it has a function: it reflects our ability to hold shared attention with others, which could also indicate that someone else is aware of the same thing that we are. Pretty meta. Joint attention can thus be associated with an ability to infer others’ mental states, which is considered an important social capability in humans.
At about six months, children start following the gaze and gestures of others. We start pointing around our first birthday and become increasingly point-savvy as we age. When toddlers see something of interest and point at it, they become excited when we also look. They will also point when seeking something or to provide information (I want that. You dropped something). Regardless of how it’s used or understood at any given age or moment, pointing intrinsically aids our communication with one another.
Do Dogs Get the Point?
It shouldn’t come as a surprise that much of the academic interest in the canine mind that blossomed in the late 1990s was actually largely about us, investigating to what extent dogs responded to our communicative gestures— notably, our pointing. In research labs around the world, it has been a pointing party ever since.
Watch any program covering research into the canine mind and you’re bound to hear mention of studies involving a dog, two cups and a pointing human. The experiment, commonly referred to as the object-choice task, follows some variation of this procedure: a dog first learns he can get a treat for approaching either of two identical cups. He then watches as a person points to one of the cups. Will the dog follow the point to the cup?
Human children are quite good at this task, and numerous studies confirm that dogs are, too. From an early age, dogs are highly responsive to this gesture. Dogs do well when a person points with a foot, or bows or nods. They’ll also respond to what’s commonly referred to as a “momentary” point, in which the person points and then lowers his or her arm before the dog makes a choice. They will follow the point even when a person stands by one cup and points at the other. Although we all know smell is a major player in the canine world, it doesn’t appear to factor greatly into dog performance; when food is hidden under one cup and nobody points, they don’t do so well. Some researchers describe their performance as “remarkable” and “outstandingly flexible.”
Not all species catch our communicative drift. A bee that flies into your car will never be aided by your outstretched arm pointing toward the open window. Given dogs’ long history with us, researchers wondered whether canine sensitivity arose through the domestication process—in which case, wolves, their closest relative, might be less adept in this task—or, on the other hand, whether it’s a product of learning and dogs’ individual life experiences. Or maybe the reality is not so black-and- white. What underlies their highly flexible ability?
Wolves do not follow our gestures as flexibly as dogs. Nor do chimpanzees, our closest relatives. This isn’t to say that wolves (or chimpanzees) can’t or don’t do it. Extensively socialized wolves and enculturated chimps—those highly familiarized with human behavior— can follow our points, but dogs generally respond more readily and easily, and wolves need more exposure to perform similarly. In 2002, Brian Hare of the Duke Canine Cognition Center pulled together then-current research on dogs, wolves and chimpanzees and, in an article in Science, concluded, “Dogs’ social-communicative skills with humans were acquired during the process of domestication.”
Both Nature & Nurture Point to Success
More immediate genetic influences, like artificial selection, could also influence dogs’ skills. Márta Gácsi and colleagues at the Family Dog Project in Budapest found that while all dogs tested followed the point better than chance would predict, dogs bred for cooperative work (like gun dogs) performed better than those bred for independent work (like guard dogs). All the dogs in the study were living as pets and none had received special training, implying that genetics plays a role at some level in enhancing dogs’ ability to follow our gestures.
At the same time, individual life experiences could also contribute to a dog’s responsiveness. For example, the reactions of shelter dogs to our pointing gestures vary widely, and a small group of intensively socialized lab-raised dogs did not fare well in the task.
Lucia Lazarowski of the Comparative Cognition Laboratory at Auburn University, one of the investigators in the lab-raised dog study, saw their challenges first-hand. But when she later adopted Captain, a study participant, and informally examined his responsiveness to pointing, she found he performed much better in her home: “He actually looked in the direction I pointed and sniffed in the area I was pointing to. During the test, however, he was one of the more non-responsive dogs. Now, we like to play a game where I toss small treats around the room for him to hunt, and if he can’t find them, sometimes I’ll point to them, so he probably has picked it up from that.” Captain’s transition to canine pointfollower highlights that learning and life experiences can factor into the skill.
The person behind the point can also affect dog performance. Amy Cook, CDBC, CPDT-KA, conducted a study on the topic at the University of California, Berkeley; reporting in Animal Cognition, Cook noted that when owners and strangers were pitted against one another (in what I hope was described as a “point-off”), dogs tended to follow their owners, even when they received no reward (i.e., the point did not lead to the dog getting food). As Cook explains, “Dogs make decisions by attending preferentially to social signals from humans with whom they have become more familiar.” Many of us think it’s all about us, and our dogs might agree.
If dogs respond to the pointing gesture based on whose finger is doing the work, then again, it looks like life experiences could be controlling the switches. But not so fast: Cook suggests that this unique spin on the issue— dogs being more attentive to a familiar person—could have been shaped by evolutionary pressures to bond with a caretaker. Attachment relationships between dogs and their humans are well documented and, as Cook says, going with your person could be “a successful strategy in the long term.”
Isn’t it nice when everyone can be right? Dog responsiveness to our communicative gestures could be a product of their evolutionary history plus their ability to learn rapidly once in a human environment. In a 2009 article in Behavioural Processes, Pamela Reid, CAAB and vice president of the ASPCA’s Anti-Cruelty Behavior Team, reflects on what’s behind canine responsiveness to our social cues: “Dogs are too skilled for it to be pure trial-and- error learning. Yet it is improbable that a versatile behavior like this would be largely innate.” She suggests that what we see in dogs is an adaptive specialization of learning. “In essence, they come with a built-in head start to learn the significance of people’s gestures, in much the same way that white-crowned sparrows acquire their species-typical song and ducklings imprint on their own kind.” This fits in well with what is understood of instinctual or innate behaviors. As Jack Hailman explained in his inf luential piece in Scientific American in 1969, “How an Instinct Is Learned,” species-specific behaviors require some amount of experience and development.
When Patricia McConnell, CAAB, mulled over the pointing research on her blog, “The Other End of the Leash,” she agreed that dogs could be “predisposed to learn to follow a pointing gesture.” McConnell also highlights something you might have seen yourself: present a very young puppy with an outstretched finger and that puppy is going to approach your fingertip, not follow it to a distant location. McConnell’s point is that point-following in puppies is not automatic, although they learn it very easily.
To this, Reid adds, “Just because a skill appears early in development does not preclude learning. It does, however, demand that puppies be highly attentive to the actions of humans, a tendency that has been confirmed in studies of dog-human attachment.”
What Do You Understand, Dog?
What do dogs think of all this? What does it mean to be a dog who “understands” our pointing gesture?
A 2013 article by Ádám Miklósi and József Topál of the Family Dog Project in Trends in Cognitive Sciences concludes by highlighting that “dog social competence [appears] sometimes ‘infant-like’ or ‘human-like,’ but, importantly, the underlying mental mechanisms may turn out to be quite different.”
It’s hard enough for us to figure out if, for example, our boss is merely suggesting that we do something or telling us to do it. The same is true for dogs and the pointing gesture. Do dogs see pointing as an imperative—“You. Go there.”—or as simply providing information or a helpful suggestion—“I recommend that you go there.”—a subtle yet meaningful difference. A 2011 article published in Applied Animal Behaviour Science by Helene Pettersson and colleagues found that, like children, dogs are more likely to follow a point when it is accompanied by a cooperative tone of voice as opposed to a prohibitive tone. At the same time, dogs sometimes follow the point to an empty container, leading some to wonder whether, under certain circumstances, dogs might perceive the gesture as a command.
Like humans, dogs seem to distinguish when communication is—or is not—intended for them, although they could be relying on a more limited set of cues. Numerous studies find that initiating eye contact and using high-pitched vocalizations help dogs understand that the communication is for them. Setting is also important. In a 2011 study reported in PLoS ONE, Linda Scheider and colleagues found that if a person points to a location where a dog has never experienced reinforcement, the dog is not as likely to follow as he would be if he had previously received reinforcement there (making me wonder whether the ring-bearer dog would spontaneously follow the point to the altar).
At some level, every pointing gesture suffers from a fundamental ambiguity: we might be pointing to a particular object, or we might be pointing to a specific space that happens to be inhabited by a particular object. Usually, we can figure it out without too much cognitive difficulty. Even nine-monthold infants understand when pointing refers to an object as opposed to the place where the object is located.
How about dogs? In a study recently published in the Journal of Comparative Psychology by Tibor Tauzin and colleagues, an experimenter pointed at one of two different toys on either side of him. Before the dog could approach, the experimenter switched the location of the objects in full view of the dog. The researchers wondered whether the dog would approach the object that had initially been pointed at but that was now in a new location, or to the original location of the point. The result? Dogs did not follow the object to its new location. Instead, they approached the old location, which seems to imply that, for the dog, pointing could be more about the location than the pointed-at object.
For those of us who live or work with dogs, much of the value of pointing studies lies in what we do with the results. Despite being unflashy, the pointing gesture is actually rich in dimensions and angles that we can explore with our dogs. As Reid recommends, “Take note of your body gestures. Does your dog attend to your gestures in all cases, or only in certain contexts? Dogs are often way more sensitive than we can grasp. They’re not trying to fool you or trick you, get one over on you or cheat the system. Attending to our gestures is just what dogs do. It’s who they are.”
Cook, A., et al. 2014. My owner right or wrong: the effect of familiarity on the domestic dog’s behavior in a food-choice task. Animal Cognition 17: 461–470.
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Gácsi, M., et al. 2009. Effect of selection for cooperation and attention in dogs. Behavioral and Brain Functions 5:31.
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——— and J. Nitzschner. 2013. Do dogs get the point? A review of dog-human communication ability. Learning and Motivation 44(4): 294–302.
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Miklósi, A., and J. Topál. 2013. What does it take to become ‘best friends’? Evolutionary changes in canine social competence. Trends in Cognitive Sciences 17(6): 287–294.
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———, et al. 2013. Do domestic dogs interpret pointing as a command? Animal Cognition 16: 361–372.
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Zimmer, C. 2009. The Secrets Inside Your Dog’s Mind. Time, September 21.
News: Guest Posts
Study finds these elective surgeries influence perceptions of dog personality
July 22 2016
Just when you think you know a thing or two about dogs, there I was in Italy a few weeks ago after the Canine Science Forum, looking at a dog on the street and exclaiming, “Who the heck is that!”
“A Doberman!” offered my good friend and Do You Believe in Dog? colleague, Mia Cobb.
“Really?” I said in disbelief. Because it was true. I’d never seen a dog that looked like that. Every Doberman I’ve seen has looked like this:
Dog with docked tail and cropped ears. Credit: Figure 2. Mills et al (2016)
Not like this:
Same dog, but natural. Credit: Figure 2. Mills et al (2016)
The bottom image, of course, is the Doberman in her natural form. A dog born from two Dobermans will grow up to look like the bottom image. But the Dobermans I’ve seen have had two post-birth surgeries; their tails are shortened or docked, and the floppy part of each ear is cut, followed by the ears being taped to a hard surface forcing them to stand upright in a way they normally would not.
These cosmetic surgeries (also referred to by veterinarians as elective surgeries) are built into breed standards — see an example from theAmerican Kennel Club. Which is to say that a Doberman puppy born from two Doberman parents does not meet his or her own breed standard.
In some countries, dog surgical procedures for cosmetic purposes are restricted or banned, but in others, the practices are rampant. For example, cosmetic tail-docking is banned throughout Australia and in numerous parts of Europe, which is why I saw my first natural Doberman in Italy. In North America, things look a bit different. The American Veterinary Medical Association (AVMA) and the Canadian Veterinary Medical Association (CVMA) oppose these procedures, with the AVMA stating that these procedures "are not medically indicated nor of benefit to the patient," and "these procedures cause pain and distress, and, as with all surgical procedures, are accompanied by inherent risks of anesthesia, blood loss, and infection." Even so, restrictions are rare. As of 2014, only two states, Maryland and Pennsylvania, have any restrictions on tail-docking, focusing on the dog’s age at the time of surgery and the use of anesthesia. Only nine states regulate ear cropping.
In addition to welfare concerns associated with docking and cropping, the surgeries could affect dog social communication. Numerous studies find that tails are (gasp) useful and meaningful in dog-dog communication (more formally known as intraspecific communication, or communication between members of the same species). Even Charles Darwin recognized that tail up has a different meaning than tail down, and dogs attend to long tails better than short ones. The side of the body that a tail wags can even be informative to another dog: a dog seen wagging more to his right-side would be perceived more positively than a dog wagging more to his left. A stump is less informative.
The communicative function of dog tails has received oodles of attention (see additional readings at the end of the post), and I’m going to focus on a new issue raised last month by Marina von Keyserlingk and colleagues at the University of British Columbia in Vancouver, Canada. Their open access article in PLoS One finds that these appearance-altering procedures are not meaningless; they affect how dogs are perceived, independent of the dog's actual behavior or personality.
Study participants, United States residents participating via Amazon’s Mechanical Turk (MTurk), saw images of four dog breeds that commonly have their tails docked and ears cropped: the Doberman Pincher, Miniature Schnauzer, Boxer, and Brussels Griffon. The first three are in the top 20 of registered breeds, and the Brussels Griffon, while not as popular, was selected to include a small breed in the study.
Participants saw two different images of the same dog breed, one in the natural state (long tail and unaltered ears) and one modified (docked tail and cropped ears). They were told that the dogs were siblings and asked to explain why the ears and tails looked different.
Fifty-eight percent of participants correctly identified that “some dog breeds have part of their ears and tails surgically removed after they are born.” Dog owners were more likely to answer correctly than non-owners.
On the other hand, 40% did not know that these dogs are not born with their ears cropped and tails docked. Instead, these participants thought these traits resulted from genetic variation, agreeing with the statement, “individual dogs of the same breed vary in appearance, meaning some will have tails and ears of different shapes and sizes.” Sorry y’all. Not so for the dogs in this study! The tails and ears on the ‘modified’ dog are all us.
But what’s the effect? Another experiment in the study found that these cosmetic surgeries are not meaningless to dogs or people; in fact, these procedures affect how participants perceived dog personality traits. Generally speaking, surgically altered dogs were seen as more aggressive toward people and dogs than natural dogs, and natural dogs were seen as more playful and attractive than their altered counterparts.
But when looking at the four breeds individually, something odd popped out about attractiveness. For the Boxer, Doberman Pinscher, and Miniature Schnauzer, neither the natural or surgically altered dog was considered more attractive. Take the tail off, leave it on, crop those ears, whatever. For those breeds, people were indifferent — one appearance was not viewed as more attractive than the other. Only for the Brussels Griffon was the natural dog considered more attractive than its surgically altered counterpart.
If not all people know that the cropped/docked look is surgically created and don't find these dogs less attractive than their natural counterparts, what incentive is there to reduce these cosmetic surgeries in the companion dog population? Since 2008, the American Veterinary Medical Association has encouraged “the elimination of ear cropping and tail docking from breed standards.” Who is going to stand with them?
This story was originally published by Scientific American. Reprinted with permission.
News: Guest Posts
January 14 2015
I’ve got the ‘dog play’ bug, arguably one of the better winter bugs to have. I recently covered which toys dogs prefer (the answer: new ones, although old ones can be reinvigorated), as well as the unfortunate finding that when a dog’s not “playing right,” it could be you, not them. But toys and people are only part of play. I haven’t said anything yet about the huge topic of dog-dog play!
Fear not! Enter a new study on dog-dog play published just this month inBehavioural Processes as part of an open access Special Canine Behavior Issue. The study focuses on a particular behavior that you’ve probably seen countless times — rolling onto the back during play. The scientists came to a somewhat counter-intuitive conclusion, and if you’re like the people I hear chatting at the dog park, you might not be spot on about what it means.
Before we get to the new study, investigating what behaviors mean during dog-dog play is not new. For example, you’ve probably heard of play signals that help clarify play from not play. Play signals help say something like, “Hey, when I just bit you in the face, I didn’t mean it like I’M BITING YOU IN THE FACE. It was just for fun. See! Here’s a play bow for additional clarity. All fun here!” Play signals — like exaggerated, bouncy movements, or presenting a “play face” — start or maintain play, and they occur around potentially ambiguous behaviors — like a bite, tackle, or mount — or anything that might be misconstrued as ‘not playing.’ Play signals reinforce, “Woohoo! We’re not fighting! We’re playing!”
But not all behaviors that appear during dog-dog play are as well studied. Here to demonstrate today’s play behavior of interest is Theodore, or Teo for short. Prior to bringing his play skills to an international audience (he has his own Facebook page,Pibbling with Theodore), Teo was one of 367 dogs rescued from the second largest, multi-state dog fighting bust back in 2013. He currently lives a very different life alongside his four-legged siblings and Trish McMillan Loehr, MSc, CDBC, CPDT-KA, of Loehr Animal Behavior in Weaverville, North Carolina. Teo enjoys playing, making art with household items, and recycling.
Without further ado, Theodore in a video of slow-motion play with his “sister,” Lili (and Lili is making the slow-mo dinosaur noises).
Theodore shows many excellent play behaviors, but it’s ‘rolling onto the back’ that’s the focus of a new study by Kerri Norman and colleagues at the University of Lethbridge and University of South Africa. Their question is something you may have wondered yourself: when a dog rolls onto his or her back during play, what does it mean? Is it an indication of submission akin to a person tapping out or screaming “Uncle,” or is it instead “a combat maneuver adopted as part of an ongoing play sequence”?
Rolling onto one’s back is classically seen as a submissive gesture that “curtails active aggression.” Passive submission describes an individual voluntarily or “spontaneously [rolling] onto its back.” In a classic 1967 paper in American Zoologist, Rudolf Schenkel describes passive submission as “[expressing] some kind of timidity and helplessness.” Like coming out with your hands up or waving a white flag, passive submission is thought to prevent aggression.
Some have suggested that the rollover is still about ‘preventing aggression’ even when performed during dog-dog play. Owners observing playing dogs from the sidelines often take this a step further — the dog spending more time on its back is labeled ‘submissive’ or ‘subordinate’ while the dog on the top is ‘dominant.’ These labels often fit with a person’s worldview about dogs and asymmetries in relationships.
What if rolling over means something different when it’s during play? Norman and colleagues set out to investigate the meaning and function of rollovers during play. They wanted to know whether “rolling over onto the back and adopting a supine position” is an “act of submission” and serves to hinder subsequent aggression, or is instead, “executed tactically, for combat purposes” to solicit play, avoid a play bite (defensive maneuver), or deliver a play bite (offensive maneuver).
The researchers collected data on dog-dog play in two different contexts: staged play sessions where a medium-sized female dog was paired with 33 new play partners of various breeds and sizes, and 20 YouTube videos where two dogs played together — with half the videos including similarly sized dogs and the other half including dogs of different relative sizes.
Why the roll?
For dogs who did roll over, what did it mean? The researchers examined all instances of rolling over to see whether they were associated with submission — decreasing play, remaining passive, or being performed by the “smaller or weaker” partner — or were instead associated with the interactive, combative nature of play, where roll overs preceded “launching an attack (offensive), evading a nape bite (defensive), rolling in front of a potential partner (solicitation) or rolling over in a non-social context (other).”
The findings are stark: the smaller of the two play partners was not more likely to rollover than the larger dog. Additionally, “most rollovers were defensive and none of the 248 rollovers was submissive.” Here is a figure for you visualizers out there:
But once on their backs, maybe this is where submission kicks in? For example, a dog could go on his back to avoid a neck bite and then lay motionless, suggestive of passive submission. But that’s not what the dogs did. The researchers report, “no dog rolled over in response to an approach or aggressive action by the partner and did not remain passive in its back.” Instead, like you saw in the video of Theodore, the Playing Wonderdog, once on their backs, dogs in the supine position both blocked and launched bites at their partner.
What does this mean?
1.13.2015, 9:00 PM Updates
I am happy that so many people are discussing this study! Here are a few more important points about rolling over and dog play:
1) When two dogs are playing, rollovers most often facilitate play. For example, a dog on its back often engages in playful sparring with another dog, delivering or avoiding neck bites, or engaging in open-mouth lunges. The researchers in the above study found that the majority of in-play rollovers were part of play fighting (meaning the ‘fighting’ was itself playful, not real fighting). The important takeaway is that rolling over during play is about play, it is NOT about ‘aggression’ as this Daily Mail headline incorrectly states.
2) Another way to think about rolling over in play is as a self-handicapping behavior because it helps dogs of different sizes or sociabilities play together. Self-handicapping is instrumental to play, and it implies that a dog is tempering his or her behavior in some way. For example, during play, dogs do not deliver bites at full force, and a larger dog might roll over to allow a smaller dog to jump on or mouth him. In Inside of a Dog: What Dogs See, Smell, and Know, Alexandra Horowitz describes the behavior: “Some of the largest dogs regularly flop themselves on the ground, revealing their bellies for their smaller playmates to maul for a while—what I called a self-takedown.” The researchers in the above study note that “some of the present data indicate that the bigger dog is more likely to [rollover].” Self-takedowns can be a type of self-handicapping behavior that promote play.
This post is reprinted with permission and originally appeared on Scientific American.
News: Guest Posts
with free live streaming
June 1 2014
If you think I’m beginning to sound like a broken record, Thank You!
That means you stopped by Dog Spies in May 2013 and read a post with the same title. But that was #SPARCS2013, and this is #SPARCS2014; same concept, different location, topics and speakers. During this year’s 3-day event, June 20-22 2014, leading canine researchers will cover three general areas of research that get at the core of what it’s like to be a dog:
Topics that many dogs are sometimes better acquainted with than their humans:
SPARCS is a unique venture organized by Prescott Breeden of The Pawsitive Packleader, Seattle Dog Training and Arizona State University Canine Science Collaboratory. From June 20-22, 2014, anyone in the world can see some of the leading canine science researchers in action — either in-person in Newport, RI, or via free Live Stream to your living room (or bathroom, if that’s where you prefer to take your canine science).
SPARCS is short for the Society for the Promotion of Applied Research in Canine Science, which aptly summarizes the conference goals: (1) to promote research and education in canine science, and (2) to provide a platform for leading minds in canine science to present, discuss and debate modern behavior science. It is an international initiative to discuss what is known (and not known) about dog behavior, biology and cognition. No hooey included.
As a new addition to #SPARCS2014, Do You Believe in Dog? — featuring myself and fellow canine researcher Mia Cobb — will moderate. In conferences, I find that all the great info being discussed moves very fast. A question pops into your mind and you need clarification, but the speaker is already on the next topic.
At #SPARCS2014, Do You Believe in Dog? will act as your pause button, fielding questions and expanding on speaker content. We’ll monitor questions and comments on social media, moderate the daily panel at the end of each day (posing your pressing questions and diving into hot-button topics), and we’ll hold post-talk interviews with each speaker (of course, speakers should be prepared to field questions on Ryan Gosling and his dog). We’re putting a large emphasis on engaging both the live and online audiences, so follow along at @DoUBelieveInDog and #SPARCS2014.
Here are the #SPARCS2014 featured speakers along with their respective talks topics. Visit the conference webpage for talk abstracts and learning goals:
Ray Coppinger, PhD
Why do breeds of dogs behave differently? –> Julie comment: No simple answer here!
Simon Gadbois, PhD
Applied canine olfactory processing: What trainers need to know beyond learning theory.
It is not what you like, but what you want that counts: The neurochemistry of behaviour and motivation.
Sam Gosling, PhD
Overview of research on temperament and personality of dogs.
Kathryn Lord, PhD
Barking and conflict.
Patricia McConnell, PhD
I see what you’re saying: Translating conflict-related visual signals.
Coyotes, Koalas and Kangaroos: What the behavior of other animals can teach you about your dog –> Julie comment: I haven’t seen a talk with this scope before!
James Serpell, PhD
Individual and breed differences in aggression
What the C-BARQ can tell us about human temperament –> Julie comment: C-BARQ stands for Canine Behavioral Assessment and Research Questionnaire. Get acquainted with it here.
The influence of owner/handler personality on the behavior of dogs
Monique Udell, PhD
Integrating ethology, learning theory & cognition in animal training
Clive Wynne, PhD
Does the name Pavlov ring a bell? –> Julie comment: I’m sure trainers and owners want to know, “Do some approaches to dog behavior have more of a basis in learning theory than others?”
Prescott Breeden, BM, CCS
The phenotype of molecules: Why nature vs. nurture is the wrong question –> Julie comment: And the right question is…
#SPARCS2014 also features short presentations from emerging researchers. Check out the SPARCS Facebook page for speakers and topics.
Each year, the SPARCS conference and initiative is made possible by you. “Donations are absolutely optional however graciously appreciated.” Check out donation and membership opportunities.
Stay in touch with the SPARCS initiative on Facebook and Twitter.
Did you catch #SPARCS2013? Maybe you watched the Free Livestream or even attended in person. What was it like? And what are you looking forward to at #SPARCS2014?
This article first appeared on Dog Spies, Scientific American. Used with permission.
News: Guest Posts
May 22 2014
I judge dogs when I meet them, but not in the way you might expect. You see, every dog and owner I meet gets filtered through a lens called “Potential Canine Science Study Participants.”
The growing field of canine behavior and cognition research is not built on the backs of lab beagles. Instead, research depends on the kindness and interest of dog owners who sign up their dogs to join any of the canine studies around the globe.
So whenever I meet a dog in NYC, I’m thinking, “Would your human companion be interested in signing you up for a study at the Horowitz Dog Cognition Lab?” And, just as important, “Would you, Mr. or Ms. Dog, be interested in participating in a study?” Nine out of ten times (not an exact science) the answer is yes.**
But dog participation doesn’t always go as planned. Which leads to one of the most interesting yet overlooked sections of research papers — the section that reports the dogs who didn’t make it into the final results. A blooper reel of sorts. These nuggets hidden in dense research papers offer little windows into the world of dogs and canine research methodologies. Why did a dog not perform according to plan? Was the dog not interested in playing along with the tasks required by the study? Or maybe the owner or experimenter goofed up the execution. Let’s take a look:
A 2010 study by Kundey et al. dropped six subjects:
Another study by Range et al. (2009) required dog subjects to “give a paw” to an experimenter numerous times. A number of subjects didn’t make it into the final results:
So when working with dogs, not everything is going to work for every dog, and things don’t always go as planned. After all, do other areas of science have to worry about a squirrel mucking up their study?
**This participation rate is high because, like most canine behavior research, our work incorporates a variety of methodologies that are a good fit for dogs with different personalities: some studies include food and treats while others don’t, some include the presence of other dogs, others don’t, some include the direct participation of owners, other don’t … some include nuts, Mounds don’t … you get the picture. Owners complete a short online questionnaire and bam! They’re added to our database of “People interested in participating in canine science studies at the Horowitz Dog Cognition Lab.” They’ll then be contacted about our future studies. And, for a somewhat comprehensive list of canine behavior and cognition groups around the globe, check out my website. Other canine research groups are looking for study participants too!
Images: Flicker Creative Commons: dogs and squirrel.
This story was originally published on Dog Spies, Scientific American. Reprinted with permission
News: Guest Posts
May 15 2014
Unfortunately, this is true. I’ll explain.
Dogs are trained to sniff out a lot of things, and some of those “things” are human remains. Human remains, except those in a cemetery, are usually not out in the open; someone doesn’t want them found or there has been an accident. But bring your own Scooby Doo to the case, and you might have a fighting chance.
But how do dogs get into detection mode? Training can take many different forms, but customarily, trainers present dogs with a target odor (the smell of interest) and control odors (that are not of interest). They are trained to alert to the target odor and ignore the controls. Sometimes trainers use a scent detection board, like the one below that the University of Pennsylvania’s Working Dog Center uses when training dogs to alert to ovarian cancer.
To train dogs to identify and ultimately find a particular scent, trainers need samples. For different types of cancer, these samples might come from the blood, urine or tissue of a person with the target cancer. But what do you use if you are training a dog in human remains detection (thankfully given the innocuous-sounding acronym HRD)? If you are a HRD handler, how do you train and practice with your dog? Where do you get your, um, samples? Is this Dexter’s side gig?
One solution is to use nonhuman remains, as long as they are a suitable proxy for humans. A recent study by Cablk et al. (2012) compared the chemical compositions of decomposing tissue from a pig, cow, chicken and human. The researchers were investigating the volatile organic compounds (VOCs)—the “smell particles”—released by animals and humans.
The important question in the HRD field is: which VOCs are produced when a human body decomposes? Are they similar to or different from VOCs of decomposing animal tissue? Identifying the specific compounds—and their ratios—could help when training dogs, or in creating synthetic training samples. You know, so you don’t need a fridge full of—well, you get the picture.
When comparing decomposing animal and human tissue, the results were clear:“Although there were compounds common to both animal and human remains, the VOC signatures of each of the animal remains differed from those of humans.” Thank goodness. You are not a pig. Nor are you a cow. But yes, you are kind of a chicken: “The VOC signatures from chicken and human samples were most similar, sharing the most compounds of the animals studied.”
By contrast, VOCs in pig remains were not so similar to VOCs found in human remains. “In addition to sharing only seven of 30 human-specific compounds, an additional nine unique VOCs were recorded from pig samples, which were not present in human samples.”
HRD trainers sometimes use pig remains to train dogs, but given their VOC differences, are pig remains the best best? Is it better to train on human, synthetic human or even chicken remains?*
We don’t usually confuse humans with chickens, but this similarity we just can’t shake. It seems Marty McFly was wrong. Maybe we are chickens.
Cablk et al. 2012. Characterization of the volatile organic compounds present in the headspace of decomposing animal remains, and compared with human remains. Forensic Science International, 220, 118–125.
Hoffman et al. 2009. Characterization of the volatile organic compounds present in the headspace of decomposing human remains. Forensic Science International, 186, 6–13.
This article first appeared on Dog Spies, Scientific American. Reprinted with permission
News: Guest Posts
Book Review: Dog Food Logic
May 8 2014
How wonderful if you could pose this question just once in your dog’s life and receive a perfect answer that would last a lifetime. Imagine if there were a ‘right’ formula, and once you know it, you could feed your dog forever and ever on the same exquisite diet. Your dog, in return, would be the happiest and healthiest doggie camper there ever was.
Unfortunately, “What should I feed my dog?” is not the question we should be asking. In fact, “What should I feed my dog” is akin to the infomercial that comes on at 3 AM informing you that if you just buy this Mega-Blast Belt (for three low monthly payments of $19.99), six-pack abs will follow. Both fall into a quick-fix category — the “right” product, the “right” answer — that unfortunately doesn’t exist.
Instead, the question that will last you a lifetime is, “How should I feed my dog?” This is where Linda Case, M.S. comes to the rescue. I don’t mean to be superhero-y about it, but Case’s new book, Dog Food Logic: Making Smart Decisions for Your Dog in an Age of Too Many Choices is a unique work designed to help readers make informed, science-based decisions on what and how to feed our beloved companion dogs. As one veterinarian offers, “Dog Food Logic cuts through the noise and chaos and provides pet owners with a rational, science-based approach to evaluating their pets’ dietary needs and their feeding choices” (The Skeptvet Blog).
Linda Case knows a thing or two about animal nutrition. She earned her B.S. in Animal Science at Cornell University and her M.S. in Canine/Feline Nutrition at the University of Illinois. She maintains the well-received blog, The Science Dog, and has written numerous books on companion animal nutrition, training and behavior. I had the pleasure of meeting her at the Cats in Context conference at Canisius College in 2013 (Case spoke on cat nutrition, and I gave a talk on research into whether dogs and cats in the home can be friends — they can).
But back to dog food. If you are expecting a dry read on dog nutrition and diet, you’ve come to the wrong place. Dog Food Logic is a page turner, jam-packed with real-world examples that you can easily relate to. Case unpacks label claims, fad diets and the wonderfully persuasive field of pet food marketing. What does it mean when a food is ‘recommended by veterinarians or breeders?’ Who is Chef Michael, and should you trust him? And who’s keeping our dog food safe?
Throughout the book, Case discusses research into canine nutrition and diet in a way that is easy to digest, if you’ll pardon the pun. For example, studies have investigated:
This is just the tip of the iceberg, and since I can’t possibly summarize all the topics and findings covered in Case’s book, the above are intentional teasers. To find out more, read the book.
Case, L. 2014. Dog Food Logic: Making Smart Decisions for Your Dog in an Age of Too Many Choices. Dogwise Publishing.
Case, L. The Science Dog blog.
Hecht, J. 2013. Dogs and Cats in the Home: Happiness for All? Dog Spies and Do You Believe in Dog?
McKenzie, B. The SkeptVet blog.
This article first appeard on Dog Spies, Scientific American. Used with permission.
News: Guest Posts
January 24 2014
As my Twitter bio says, I’m interested in your dog’s urine. I’m not kidding around here. For a recent Animal Behavior class, I buddied up with a doggie daycare and followed dogs on their afternoon walks. Yes. I was that person walking around NYC with a hand held camera, trailing dogs and video taping them as they peed.
This wasn’t a hypothesis testing experiment, I was simply trying to gauge what parts of urination were easily measured in a naturalistic context. I checked out things like urination duration, urine placement, leg position, leg height, tail position and post-pee scratching. If another dog was present, I got to see whether there was any over-marking (peeing on another dog’s pee) or adjacent marking (peeing nearby). I was just measuring stuff as you often do when starting to investigate why animals do what they do.
I’m not the only researcher interested in your dog’s urine. Patricia Yang and colleagues at The Georgia Institute of Technology have a similar interest in measuring things that might seem odd to measure. They’ve submitted the abstract The Hydrodynamics of Urination: to drip or jet to the Annual Fluid Dynamics Conference held by the American Physical Society in late November.
Using “high-speed videography” and “flow-rate measurement” they investigated independent urination styles, such as the dripping of small mammals and the “jetting” of large mammals. New Scientist interviewed Yang (and Discover has a piece out as well), and the coverage touches on urethra length, gravitational pull and the number of seconds it takes to empty bladders. I eagerly await how the published study links Newtonian physics to urine!
Truth be told, maybe I wanted to write this post so I could write “jetting” of large mammals, and show this video. Also, I want to go on vacation with these people*:
But as you’ve seen, urine does not begin and end with the jetting of large mammals. Dog urination is pretty awesome and a number of researchers are holding a figurative magnifying glass up to it (and you can too!). Some dogs let it all out at once — although, I’m pretty sure that’s not called “jetting”) — while others let a little out at a time. And then of course, there’s how they do it.
A recent study by Wirant and McGuire (2004) found that female Jack Russell Terriers assumed a number of urination positions, including the squat-raise (most common), squat, arch-raise, combination and handstand. They found that females“used the squat-raise and arch-raise postures more when off their home area then when on their home area.” If dog urination has a social function, it might make sense to present your urine in different ways depending on where you are and who you are encountering, don’t you think?
Here’s what you can do: When you’re out walking your dog, pay attention to their urine. Do they assume a different position if you take them to an area where they’ve never been or go infrequently? Or do they pull out the same tricks no matter where they are?
Leave your urine reports below, and share early and often. My business is urine, and it can be yours too.
Photo: Flickr Nature’s Fire Hydrant via Mike Finkelstein Creative Commons
Pham et al. 2013. The Hydrodynamics of Urination: to drip or jet. Bulletin of the American Physical Society. 66th Annual Meeting of the APS Division of Fluid Dynamics.
This story was originally published by Scientific American. Reprinted
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