Culture: Science & History
"Though in their deep heart’s core, there is a commonality of origin, spirit, emotional intelligence and empathetic sensibility, the wild wolf looks through us, while the dog looks to us. "
Of all the myriad members of the animal kingdom, the domesticated dog (Canis lupus familiaris) is closest to us. With individual exceptions in other species, this canine species is the most understanding, if not also the most observant, of human behavior—of our actions and intentions. This is why dogs are so responsive to us, even mirroring or mimicking our behavior. And it is why dogs are so trainable.
Fear in unsocialized and abused dogs interferes with their attentiveness to and interpretation of human behavior and intentions. This is one reason wild species like the coyote and wolf, even when born and raised in captivity, are difficult to train. The wolf “Tiny,” whom I bottle-raised and intensely socialized during her formative early days, never really lost her fear and distrust of strangers.
Tiny did not start mirroring human behavior until she was close to nine years old. At this point, she began to mimic the human-to-human greeting grin, revealing her front teeth as she curled her lips into a snarly smile. In my experience, dogs who can do this do so at a much earlier age, even as early as four to six months.
In comparing socialized (human-bonded) wolves and dogs in terms of how they have related to me as well as to my family members, friends and strangers, I would say that the main difference between the two species is the fear factor. Differences in trainability hinge on this; as I theorize in my new book (Dog Body, Dog Mind), domestication has altered the tuning of the dog’s adrenal and autonomic nervous systems. This tuning (which dampens adrenal fright, flight and fight reactions and possibly alters brain serotonin levels), is accomplished through selective breeding for docility, and by gentle handling during the critical period for socialization.
According to the earlier research of my mentors—Drs. John Paul Scott and John L. Fuller of the Jackson Laboratory in Bar Harbor, Maine—pups with no human contact during this critical socialization period (which ends around 12 to 16 weeks of age) are wild and unapproachable.
When we peel off the wolf’s innate fearfulness and put it on the dog, we turn the dog into a feral facsimile of a wolf. But a human-socialized wolf without fear could be an extremely dangerous animal, even attacking a human perceived as a pack rival. This happened to me in the 1970s during the filming of the NBC documentary, “The Wolf Men.” An alpha male wolf, along with his female cagemate who was in heat, had been released into a large wooded compound belonging to my friend, the late wildlife illustrator and conservationist Dick Grossenheider. Earlier that memorable morning, the she-wolf had greeted and solicited me, a total stranger, when I had visited the two wolves in their enclosure. (I am not saying that a male dog would never react to me in a similar way under comparable circumstances; I was once urinated on by the alpha male lead sled dog of a well-known racing pack in a similar situation.)
Canine Evolution and Human Needs
We see many things in our dogs’ eyes, the windows of their souls. They are also mirrors of the human soul, since every pair of dog’s eyes reflects—for better and for worse—how well that dog has been treated by our own kind. Dogs read our eyes and are attentive ethologists of human behavior, action, emotion and intuition. A change in tone of voice can make a dog tremble in fear or dance and yap for joy. Such ability to read human behavior, intentions and emotions was naturally selected for as dogs domesticated themselves and adapted to life with Homo sapiens, the “killer ape.”
Civilizing the Killer Ape
These half-human killer apes were never to be fully trusted, however, since when they were very hungry, or warring between themselves, they would often engage in cannibalism, as today, people still kill and eat dogs for sustenance and “good medicine.” (See James George Frazer’s The Golden Bough.).
Just as not every dog is fully domesticated, in that some can still turn feral, and others turn on their masters, so the wolf has failed to fully domesticate and civilize the killer ape. We still wage war with our own kind, and ignore the biological wisdom and prescience of such injunctions as do no harm, resist evil and treat others as we would have them treat us. All good dogs know this, and show it in their eyes and behavior. (But they have not forgotten how and where to bite!)
The secure, well-loved and understood dog is more often an extrovert than an ambivert wary of strangers. Secure, well-loved and understood wolves, in contrast (with few exceptions, some of whom become more easy-going around new people and in new places as they grow older, as did Tiny in her early teens), are more often ambiverts or introverts. They are fearful when meeting unfamiliar people. Differences in individual, breed and species autonomic tuning (as mentioned earlier) also account for differences in disease resistance, temperament and learning ability.
The Canid Conscience
Good dogs can see and respond to our own deep heart’s core of love and devotion because it is from this center of our own being that we embrace and celebrate theirs. That is what Franz Kafka in his essay, Investigation of a Dog, meant, I believe, when he wrote: “All knowledge, the totality of all questions and all awareness, is contained in the dog.” And this is why the ancient Egyptians believed that dogs were our guide in the afterlife—they were such good guides and loyal companions in real life. Embodying finer qualities of feeling and sensibility than the relatively irresponsible and emotionally challenged average human, dogs are worthy of being looked up to with awe and gratitude. We should help others of our own kind feel and know that in the deep heart’s core of all good dogs and wild wolves lies the source of an abiding affection that we, in moments of grace and communion, may share.
Since this core is as evident in a wolf as it is in a Toy Poodle, it is clear that neither domestication nor wildness has altered their true natures. In the heart of every dog is the spirit of the wolf that embodies the finer qualities of human nature that we call love and devotion.
News: Guest Posts
I had watched the dog origin wars as a chronicler of the dog-human relationship for several decades when in 2009 I was approached a young editor The Overlook Press about writing a book on the origins of the dog. I readily agreed, and the result was How the Dog Became the Dog.
Pondering the conflicting dates, places, and theories associated with the emergence of the dog, I concluded that as soon as our forebears met wolves on the trail they formed an alliance of kindred spirits, and the process began. Their basic social unit was a family with ma and pa at the head and young ones of varying competency. They worked and hunted cooperatively. They were consummately social but capable of prolonged solo journeys.
It made sense that the Middle East, if not North Africa, was where this all started because that would have been the region of first contact. But because of their natural affinity, wolves and humans got together wherever they met. Some of the resultant “dogwolves”—my phrase for doglike wolves or wolves that act like dogs—created lineages that survived a while then fizzled out; others endured.
I identified several hotspots for early dogs across Eurasia and a group of humans that at least according to genetic evidence might have made its way through the cold of the last Ice Age from the Persian Gulf oasis, then a fertile land, to the Altai Mountains of Central Asia, a region that also hosts the headwaters of the Amur River, still famous for its wildlife. This group’s dogwolves mixed and matched with others along the way, especially the big mountain dogs of the Caucasus. This group of hunters and foragers gathered in the Altai around 40,000 years ago and from there ultimately took the New World.* They also went with their dogs, I calculated, south and east into China, Korea, and Japan and west again with their giant dogs, now mastiffs.
I based that conclusion in part on the types of dogs found in the New World. It made more sense that the possibility for the phenotype was present even if the phenotype itself was not manifest than that it was introduced later.
It was with some interest, then, that I read in PLoS One for July 28, 2011, about a 33,000 year old ‘incipient” dog from the Altai Mountains—that is, an early attempt at a dog that went nowhere. The finding was immediately challenged, and the fossil dismissed as a wolf, even if a strange one. So a new team of researchers redid the work in Robert K. Wayne’s evolutionary biology lab at UCLA and on March 7, 2013, published an article in PLoS One confirming that the 33,000 year-old-fossil is that of a primitive dog.
Writing for their colleagues from Russia, Spain, and the U.S., Anna S. Druzhkova of the Siberian Branch of the Russian Academy of Sciences and Olaf Thalmann of Turku University, Finland, state that when compared with other canids, the Altai dog, as it is known, shows closest affinities with New World dogs and modern dog breeds, ranging from Newfoundlands to Chinese Cresteds and including cocker spaniels, Tibetan mastiffs, and Siberian huskies.
Equally interesting from my perspective, the Altai dog does not appear to have been related closely to wolves in its immediate vicinity or to modern wolves. It came to the Altai from elsewhere, probably with people.
The researchers emphasize that there is uncertainty in their findings because they are based on a single region of mitochondrial DNA. But from my standpoint, the work provides one bit of evidence that’s I’ve not been barking up the wrong tree—and that seems worth noting.
*Ted Goebel et al., “The Late Pleistocene Dispersal of Modern Humans to the Americas,” Science, March 14, 2008. Connie J. Kolman et al., “Mitochondrial DNA Analysis of Mongolian Populations and Implications for the Origin of New World Founders,” Genetics, April 1996.
Good Dog: Behavior & Training
More than just noise
A friend suggested that one of the reasons we love dogs so much is that they can’t talk back. But I wonder whether that’s true. Sure, a dog won’t tell you, “You really shouldn’t have that second cookie,” but does that mean dogs are not talking back?
Dogs are anything but mute, and while we usually focus on wagging tails and beguiling eyes, vocalizations—among them, barks and growls—provide us with another window into dogs’ everyday experiences.
Social species are known to be much noisier than animals who lead solitary lives. Snow leopards roam the mountains of central Asia in near silence, but groups of monkeys do a lot of highvolume chattering. So, given that dogs and their wild progenitor, the wolf, are über-social, it’s no surprise that both produce a wide range of vocalizations: they bark, whine, whimper, howl, huff, growl, yelp and yip (among other nuanced sounds). From the earliest moments of their lives, dogs and their canid relatives produce tonal yelps and whines, and atonal barks and grunts appear in the fi rst few weeks of life in conjunction with the onset of social behavior.
There’s a big difference between the bark of an adult dog and that of an adult wolf, however. Dogs seem to play every instrument in the orchestra, hitting the highs of the flute and the lows of the tuba, sometimes with the duration of a Wagnerian opera. Plus, there seems to be no context in which a dog won’t bark: They bark when alone and with other dogs. Some bark before, during and even after a ball is thrown. A car goes by or the doorbell rings and barking ensues. In contrast, wolves bark less frequently and in fewer contexts, primarily for warning or defense.
Meanings Behind the Message
That being said, research that has been conducted on the subject is incredibly insightful. Take growls, which, it has been shown, dogs use to accurately judge another dog’s size. How in the world do we know that? Tamás Faragó, PhD, and his colleagues at the Family Dog Project at Eötvös Loránd University in Budapest (familydogproject.elte.hu) presented dogs with two images of the same dog: one was true to size and another was 30 percent larger or smaller. Dogs then listened to a pre-recorded growl, and most dogs looked at the image of the full-size dog rather than the altered image.
Growls appear to be meaningful in other ways as well. In another study, Faragó and his colleagues used some clever trickery to explore how dogs respond to growls recorded in different situations. In an apparently empty room, a dog was allowed to approach a bone. Unbeknownst to the dog, there was a speaker hidden behind the bone, and as the dog approached, the sound of a “play growl,” a “stranger-approaching” growl or a “food-guarding” growl was transmitted through it. Dogs were likely to take the bone when hearing the “stranger-approaching” or “play” growl, but the food-guarding “my bone” growl deterred them. Even though the foodguarding and stranger-approaching growls sound quite similar (at least, to our ears), they prompted different behavior.
Many studies investigating vocalizations are based on prerecorded samples, but it is important to remember that vocalizations and visual signals usually go hand-in-hand. In the strangerapproaching context, dogs growled with closed mouths, whereas in fooddefense situations, they showed their teeth and pulled back their lips.
While we tend to take notice when we hear a growl, we often dismiss barking as meaningless noise, as though it is simply an item on a dog’s daily checklist: “Take a walk, have breakfast, bark.” Before the turn of the century, that was the prevailing view among researchers and theorists. At most, barking was thought to result from social facilitation— one dog barking prompts other dogs to bark—or maybe attentionseeking, or even rivalry or defense.
Only recently have researchers begun to investigate whether barks produced in different contexts vary in their acoustic parameters (such as tone and pitch). Scientists theorized that if— like growls—barks displayed consistent differences, they might have a more specific communicative function, perhaps even be associated with a dog’s internal motivational or emotional state. For example, some barks might convey aggression while others might convey friendliness.
In one early study, Sophia Yin, DVM, MS, recorded a variety of breeds barking in response to different situations: a stranger ringing the doorbell (“disturbance barks”), separated from an owner (“isolation barks”) and play. Yin found that the barks did indeed have different acoustic properties. Disturbance barks were harsher and lower in pitch with little amplitude modulation, while isolation and play barks were pitched higher and had greater tonal and higher frequency and a wider range of amplitude modulation. More recent studies confirm that dog barks follow particular patterns. For example, a dog barking at a stranger sounds very different from a dog barking before going on a walk. But do these vocalizations carry meaning? They do for dogs. When dogs in one study listened to barks recorded in a new context or from a new dog, they gave more attention to the unfamiliar bark. This suggests that dogs can detect that some barks are different from others, though scientists are still exploring ways to determine how exactly they perceive and process that information. Humans, too, can decipher barks. Whether or not they’re experienced with dogs, people are quite good at classifying barks into their appropriate contexts and attributing them to perceived emotional states. After listening to randomly played recordings, people describe isolation barks as full of despair, while barks from a play session are said to be happy. Our ability to do this starts early; by age 10, children are able to assign different-sounding barks to the correct context. Today, we can distinguish the acoustic properties of certain barks so accurately that we’re able to program computers to categorize them (which confirms that computers will one day take over the earth; personally, I hope Ryan Gosling will be there to save us).
Recognizing the Patterns
A recent publication by Kathryn Lord, PhD, offers an additional take on why dogs bark. She and colleague Ray Coppinger, PhD, investigated the contexts in which other species use barklike sounds: “When other species emit their version of a bark, they are usually in some sort of conf licting situation. For example, an animal is at a nest or den and observes some sort of threat. Customarily, the animal would run, but because of its situation, it can’t, so it barks. We think [that] when dogs bark, they are making these sounds in association with an alert or an internal motivational state of conflict.”
In a sense, Lord and Coppinger argue that “conflicted” should be dogs’ middle name. They suggest that dogs bark in so many different situations because they often find themselves conflicted: they are in the house and want to go out, they are out and want to come in. And it may be that, through the process of domestication itself, dogs have become more prone to put themselves in these sorts of situations. In comparison with wolves, dogs have a substantially decreased f light distance; something can easily get too close before the dog feels conf licted about how to respond.
Udell suggests that barking doesn’t have to be whittled down to one simple explanation. “If you look at communication and vocalizations in a wide range of species, it usually isn’t about one thing. Chickadees have ‘alert’ calls, but they also have songs, and the songs themselves can mean different things in different contexts. I think the same could hold true for dogs.”
But genes aren’t everything. As Susan Friedman, PhD, a pioneer in the application of applied behavior analysis to captive and companion animals and a psychology professor at Utah State University, explains, “While Shih Tzus as a group tend to display less barking than Miniature Poodles, that doesn’t mean barking in Miniature Poodles is impervious to change. And I’ve certainly known individual Miniature Poodles who are quiet and individual Shih Tzus who are barky, both based on their current situations. The individual always bests any generalization.”
Dr. Yin’s study of dog barks concurs. Even within breeds, she found variations in who barked and when. Rudy and Siggy, 11-year-old German Shorthaired Pointers, both barked in the disturbance context, but when alone, Rudy did not bark and Siggy had lots to say.
The effects of the social environment on dog behavior can be important because sometimes, dogs just go with the flow. On The Bark’s Facebook page, Bev Morey of Kansas commented, “After attending day care each afternoon, my Weimaraner now barks at anything and everything. So annoying.”
“So annoying” is one of the challenges of barking. While all vocalizations, including barking, are generally seen as normal elements of dog behavior, barking is one of dogs’ less-appreciated attributes. According to Laura Monaco Torelli, CPDT-KA, KPA CTP, director of training at Animal Behavior Training Concepts in Chicago, “Barking can be especially challenging for those in urban settings, as they live in close quarters with neighbors.” Owners of barking dogs might receive dirty looks or formal complaints from neighbors, and enough complaints can lead to eviction.
Though dogs bark for any reason under the sun, barking is a construct of context, genes and environment, and so is flexible. For example, feral dogs are much less noisy than their counterparts who play with toys, sleep in beds and go to obedience class.
Friedman explains. “For dogs, barking is a functional behavior, meaning it is maintained, increased or decreased due to consequences. Once this is [understood], it opens the door to changing the duration, intensity and frequency of the behavior by changing the consequences.” In other words, dogs can learn to be quieter.
However, perfect quiet is probably unrealistic. Owners can’t always control the stimuli that prompt barking, especially if they’re not home 24/7. Moreover, barking that has been solidified and maintained over time through intermittent reinforcement has a lot of staying power. “It seems that owners unintentionally reinforce the barks produced when a dog is around food or toys, and these become the begging barks of that dog,” says Faragó.
Monaco Torelli agrees. “If a dog learns that the noise in the hallway goes away when he barks, barking becomes an effective behavior. Barking is followed by the consequence of the noise in the hallway stopping.”
Owners should focus not on eliminating barking altogether, but on reducing it to levels they find appropriate and livable. When she meets with clients to discuss their dogs’ barking issues, Monaco Torelli asks questions such as, “How many barks is okay? What’s excessive to you?” This, she says, gives the trainer a good starting point from which to develop a plan to teach the client how to reshape a dog’s barking behavior. Trainers and owners discuss acceptable barking, and then implement techniques to achieve desired levels in each context.
Friedman shares the way she manages her own dog’s barking: “We live in the country, and when we let the dogs out, they bark at the deer for a number of seconds. Then we say, ‘That’s enough, thank you,’ and they are quiet and we praise them.” She adds, “It’s a [mistake] to think that barking is the problem. The real problem is that dogs don’t stop barking when we ask.”
So-called “quick fixes” can make barking worse, particularly if the underlying reason for the behavior isn’t addressed. “Putting an anti-bark collar on a fearful dog is unlikely to decrease barking if the consequence [shock or spray] increases the dog’s fear. If the fear increases, barking could as well,” explains Marylandbased Mary Huntsberry, MA, ACAAB.
Strategies for Change
Barking can be managed and modified, so if you want to influence your dog’s vocal style, it helps to start early and be observant. Teaching dogs the boundaries of acceptable vocalizations from an early age will pay off for everyone; when dogs are young, barking might be cute, but as they age, the cute factor tends to wear off. If the behavior is already in place, there are ways to alter it, Huntsberry observes. “It helps to do a functional analysis. During an extensive interview, I identify what happens immediately before (antecedent) and after (consequence) the unwanted behavior so I can identify the trigger and what maintains it.”
Monaco Torelli focuses her attention on the dog-human relationship. “When owners are frustrated by their dog’s behavior, we show them some immediate training goals and success points so they see that their dog can do what they want them to be doing, instead of what they don’t want them to do. This helps them rebuild their bond with their dog.”
The takeaway message is that barking is a nuanced and flexible behavior, and relationships can grow by paying attention to what your dog’s vocalizations mean. And if you’re on a post-holiday diet and want to train your dog to bark incessantly whenever you make a move for another slice of cake, well, that’s just good teamwork.
News: Guest Posts
Dogs and wolves share a similar genetic profile. So why are their behaviors so different?
The reasons aren’t clearly understood. In a recent paper in the journal Ethology , evolutionary biologist Kathryn Lord's doctoral research (University of Massachusetts, Amherst) suggests differences in later behaviors might be related to the pups' earliest sensory experiences during the critical period of socialization, the brief period when a puppy's exposure to novel things results in long-term familiarity.
Lord's research demonstrated that dog and wolf pups acquire their senses at the same time:
· Hearing: Onset 19 days, reliable by 28 days
· Seeing: Onset 26 days, reliable by 42 days
· Smelling: Reliable by 14 days (onset likely earlier)
· Dog pups wait until 28 days to explore their environment when all senses are operational.
· Wolf pups begin exploring the world at 14 days, relying solely on scent, when they are still blind and deaf.
Although wolves are tolerant of humans and things they were introduced to during the critical period, they don't generalize that familiarity to other people or novel things when they mature. Dogs on the other hand, can generalize, and if properly socialized are not spooked by novel sounds and sights.
Why do mature dogs and wolves behave so differently? Lord's conclusion is that at the gene level, the difference may be when the gene is switched on, not the gene itself.
What could that mean? Research has shown that the brain is capable or rewiring itself in dramatic ways. Early loss of a sense affects brain development. For instance, even though the developing auditory cortex of a profoundly deaf infant is not exposed to sound stimuli, it doesn't atrophy due to lack of use. Rather it adapts and takes on processing tasks of other senses including sight and touch. Perhaps wolves see the world in smell, and dogs see it a lot more like we do.
Click here to read the paper, A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris), by Kathryn Lord, Ethology, February, 2013.
News: Guest Posts
“Where goeth the food, so goeth the dog.” (old proverb)
The earliest archeological evidence dates dogs to about 14,000 years ago. Remains of small dogs in Israel go back 12,000 years. When people settled down in agricultural communities, they began to tinker with the natural environment, bringing about modification, intentionally or accidentally, in plants and animals. Of course dogs joined the party. They always do.
Not everyone agrees about why, where, when or how dogs evolved. But we all believe this: Whether dog domestication was accidental or intentional, abrupt of slow, happened 10,000 years ago or 80,000, domestic dogs descended from wolves and evolved with people. Perhaps it’s no coincidence then that we ask the same questions about dogs that we do of ourselves: How are we unique? Where do we come from? And when did we get here?
On Wednesday, January 23, canine geneticists announced they have identified key mutations in three genetic regions that allowed the wolf, a traditional carnivore to thrive on a carbohydrate diet. This adaptation was surely useful for opportunistic animals that were scavenging waste near ancient farming communities.
How they did it
Geneticists Erik Axelsson and his team at Sweden’s Uppsala University looked at DNA from gray wolves and domestic dogs, searching for small differences that might have shown up early in evolution as wolves transitioned to dogs. They zeroed in on specific mutations that dogs have and wolves don’t. In all, researchers found 36 genomic regions that reveal differences. Nineteen of those have to do with brain function, eight are related to the nervous system, and the rest are linked to starch digestion and fat metabolism, three of which carry instructions for making a protein that’s necessary for the digestion of starch. One is an enzyme that turns starch into sugar maltose. Another is an enzyme that turns maltose into glucose. And the third makes a protein that moves glucose from the gut into the bloodstream.
What does it mean?
If you think it answers the question as to why, where, and when dogs were domesticated, you’d be misinformed. It’s really more interesting than that.
1. Dogs eat more starch than wolves. The mutation explains why. Keep in mind that just because you have a mutation that lets you digest grain, it doesn’t mean, when given the opportunity, you wouldn’t rather have pork chops than cheerios. Just ask my dog, or my spouse for that matter. Wolves, dogs or proto-dogs (depending on your position) could have had the mutation long before humans planted grains. The study doesn’t suggest a time line.
2. Because all the breeds in the study have the mutation, the mutation occurred before these breeds radiated out from their direct ancestor. However, don’t assume that our modern breeds are representative of any dogs older than 500 years. There is a ginormous gap, at least 8 thousand years, between the ancient agrarian gang of dumpster diver dogs and the not-so-old proto dog that begat our modern breeds. Scientists don’t know if the missing link dog is extinct, and if she isn’t, they don’t know what living dogs would represent her. There’s plenty more work to be done.
3. The birth of agriculture impacted canids. But it did the same to humans, birds, insects, pigs, cows, and goats to name a few.
4. The study is a vindication for all the veterinarians who are treating dogs with kidney ailments as a consequence of the strange trend toward very expensive low-carb, raw meat diets. There’s a reason dog food is only 20- 30 % protein and 40 to 50% carbohydrates.
What others are saying
“Dogs are not just ‘tame wolves’ but have clearly adapted in a host of different ways to a very novel niche over a relatively short evolutionary timescale," said Adam Boyko, an expert on canine genetics and assistant professor of biomedical science at the Cornell University College of Veterinary Medicine and director of the Village Dog Diversity Project. “I think a lot of focus on dog domestication in the past centered on behavior and tameness. Clearly, they were important for domestication, but this paper also demonstrates genetic changes involved in diet adaptation.”
“The bigger question about the paper, said behavioral ecologist Ray Coppinger, is whether it sheds any light on the evolution of the dog -- whether they were domesticated "purposefully" by humans, or were they a result of humans creating a new niche which several species (including some Canis species) moved in and adapted to.” He added, “The researchers have done a great job showing that dogs and wolves genetically differ in their potential ability to digest starch. But it’s a fallacy to assume that the genes of the modern dogs included in the study are descended from original dogs. Thus the paper, sheds little light on the original dog, and does nothing to answer the question of artificial verses natural selection as the prime cause.”
What’s important about the study is not that it indicates when or where dogs originated. Rather, it’s a new tool that will help us understand how dogs and wolves are different. The research is groundbreaking, but it represents analysis of only 10 of the 36 genomic regions that the team identified. That means more exciting news is just around the corner.
Scholarly study takes on issues that are controversial. The dog origin debate continues to be particularly provocative. As for me, I just want to know who to thank.
Mark Derr, author of When the Dog Became the Dog has a very interesting post on this subject as well.
The genomic signature of dog domestication reveals adaptation to a starch-rich diet, Journal Nature, published on-line, January 23, 2013.
Good Dog: Studies & Research
“This is not your food! Don’t even think about eating it. This … is … not … your … food.” What do our words mean to dogs? Not that I’m about to stop speaking to dogs anytime soon, but I do wonder what my daily utterances signify to Millie, Piper, Upton and Finnegan, the dogs I converse with on a regular basis. Do I sound like a cross between Charlie Brown’s teacher and Gary Larson’s “What Dogs Hear” cartoon? Are we on the same page, or even in the same book?
I set out on a quest to explore dogs and their understanding of human language. What do we think dogs understand? A lot, according to a study by Péter Pongrácz and his colleagues at the Family Dog Project in Budapest. Thirty-seven owners provided a list of 430 different utterances that they thought their dogs knew, with each owner providing an average of 30 phrases.
Enter Rico, Chaser, Sofia, Bailey, Paddy and Betsy, companion dogs celebrated for their panache for human language. The news media hails them as “super smart,” and after meeting Chaser, astrophysicist Neil deGrasse Tyson exclaimed, “Who would have thought that animals are capable of this much display of intellect?”
So what are these dogs doing with words?
Seven years later, Chaser, a Border Collie in South Carolina, took the gold medal when Alliston Reid and John Pilley of Wofford College reported that Chaser knew the distinct names of 1,022 objects — more than 800 cloth animals, 116 balls, 26 Frisbees and 100 plastic items. Chaser knows that “Uncle Fuzz” is different from “Wise Owl,” who is certainly different from “Merlin.” This is not merely a story about Border Collies, however. Researchers recently related that Bailey, a 12-year-old Yorkshire Terrier, knows the names of about 120 toys.
Chaser and Rico also win praise for their ability to learn and retain the names of new objects. When presented with a group of toys, all of which were familiar except one, the dogs could retrieve the unknown toy when asked to fetch using an unfamiliar word. In essence, the dogs were pairing a novel object with an unfamiliar name after a single association and then remembering the name of that new object in subsequent trials. In children, this is called “fast mapping,” and it was thought to be uniquely human. Pilley notes, “This research shows that this understanding occurs on a single trial. However, Chaser needed addition rehearsal in order to transfer this understanding or learning into long-term memory.”
“That’s just training,” you might say, but this suggests that some dogs show a cognitively advanced skill where actions are understood as independent from objects. Reid and Pilley found that Chaser does not interpret “fetch sock” as one single word, like “fetchsock.” Instead, she can perform a number of different actions flexibly toward a number of different objects. Daniela Ramos, a veterinary behaviorist in São Paulo, discovered that a mutt named Sofia could also differentiate object names from action commands, suggesting these dogs attend to the individual meaning of each word.
This all seems quite extraordinary, but nothing comes free of controversy. Do dogs like Chaser and Sofia use and understand language the same way humans do, or are they merely welltrained? For example, some researchers are not certain that dogs actually “fast map”; dogs might be doing something that simply looks like “fast mapping” from the outside. Regardless, it does seem as though these dogs have a conception of objects and actions. Patricia McConnell, PhD, Certified Applied Animal Behaviorist and beloved Bark columnist, agrees. “Understanding requires that we share the same reference — that we have the same construct of an object or an action. For some dogs, it seems like they do.” Pilley concurs. “When an object, such as a toy, is held before Chaser and a verbal label is given to that object, Chaser understands that the verbal label refers to that object.”
In her book Inside of a Dog, Alexandra Horowitz reminds us that even if these are the only dogs in the world capable of using words this way, it allows us to see that a “dog’s cognitive equipment is good enough to understand language in the right context.” This body of research indicates what is possible, not necessarily what most dogs do every day.
Who Are You Living With?
Like Rocky Balboa preparing for his climactic showdown, these dogs are highly motivated. Fischer notes, “Rico was eager and hard working. You’d have to tell him, ‘That’s enough. Get something to drink. Take a rest.’” Chaser is similar, says Pilley. “She has two states—highly, highly active and recuperating and resting.”
Denise Fenzi, a professional dog trainer from Woodside, Calif., who specializes in a variety of dog sports, reminds us that this type of motivation is not necessarily the norm. “Not all dogs share this attention to words. Even in my dogs [all of whom are the same breed], there is a huge difference in ability to verbally process. I didn’t train them differently. It’s just easier for one to quickly get words.”
What dogs are able to do with language could also be explained by their tutelage. If dogs don’t learn to attach a variety of different actions to a variety of objects, it might be harder for them in the long run to be flexible with human language. Susanne Grassmann, a developmental psychologist and psycholinguist at the University of Groningen in the Netherlands explains, “Chaser was trained to do different things with different objects, and she differentiates between what is the object label and what is the action command, meaning what to do with that object.”
Ramos notes that Sofia’s relationship with certain objects was a bit different. “Throughout the training, we always paired ‘stick’ with ‘point.’ As a result, it was difficult for her to perform any other action toward the stick beside ‘point.’ If we had trained her ‘stick: sit,’ ‘stick: point’ and ‘stick: fetch,’ she would have learned that multiple actions can be directed toward the stick, and her response would probably be different. For example, when presented with a novel object, such as a toy bear, she could direct a number of different actions toward the bear, but there was a reluctance to change her action towards the stick, which could have to do with the rigidity of training.”
And even if you do explicitly teach that different words have different meanings, it can be challenging. Ramos found that learning the names of objects is not always easy for dogs. “It was hard for Sofia to learn to discriminate the names of her first two objects, but after the initial discrimination, it was like she learned to learn. It became easier,” recalls Ramos.
“Because this type of learning can be challenging, service dogs [who have little margin for error] are taught a limited, but instrumental, set of words,” explains Kate Schroer-Shepord, a qualified guide dog instructor at Guiding Eyes for the Blind in Yorktown Heights, N.Y.
Pilley found that dogs’ success at object learning depended upon the training method used. “When we put two objects on the floor and asked dogs to retrieve each object by name, they couldn’t do it; simultaneous discrimination wasn’t working. Instead, Chaser was able to learn the names of objects through successive discrimination. She would play with one object in each training session, and through play, the object assumed value. We’d name the object, hide it and ask her to find it. Discrimination testing between the names of different objects occurred later.”
Words or Melody?
Dogs derive an enormous amount of information from contextual cues, particularly our body movements as well as tone and “prosody” — the rhythm, stress and intonation of our speech. “When people talk to dogs, dogs pay attention to the melody and the mood to predict what is happening or what will happen next,” explains Fischer.
Fenzi says that dogs can just as easily respond to gibberish as to real English words; “I could go through every level of AKC obedience from the bottom to the top saying, ‘Kaboola,’ and the dog could succeed.” In many cases, dogs may be understanding tone rather than individual words.
“One of the most notable differences between novices and professional trainers is the ability to modulate the prosodic features of their speech,” notes McConnell. “The pros learn to keep problematic emotions out of their verbal cues, like nervousness in a competition, and to use prosody to their advantage when it’s advantageous, for example, to calm a dog down or to motivate him to speed up.”
In another study, Ramos explored whether, when taken out of context, dogs knew the words relating to toys they were thought to know. Most did not, much to the surprise of the owners. When the verbal skills of Fellow, a performing German Shepherd from the 1920s, were tested outside their customary contexts, Fellow knew only some of the words and actions that his owners thought he understood.
While many owners deem their dogs to be word-savvy, their reports tell a different story. The Pongrácz survey found that many words and phrases were executed only in contextually adequate situations (for example, saying “bedtime” when it’s dark and you’re in your pajamas rather than at noon when you’re in your work clothes). As with Fellow, this suggests dogs might not be attending to only words themselves.
Put Words to the Test
McConnell initially thought Willie knew the name of her partner, Jim. “To teach Willie, I would say, ‘Where’s Jim?’ and Jim would call Willie over. When Willie consistently went to Jim, I’d say it as Jim was driving up, and Willie would run to the window. One day, Jim was sitting on the couch, and I said, ‘Where’s Jim?’ and Willie ran to the window, all excited. This difference in definitions is more common than people realize — dogs don’t have the exact same concept of words that we do.”
While there is no question dogs can understand verbs, their definitions might differ from ours. McConnell shares a classic example that she learned from Ian Dunbar, founder of the Association of Pet Dog Trainers. “What do dogs think ‘sit’ means? We think ‘sit’ means this posture we call ‘sitting,’ but if you ask a dog who is sitting to ‘sit,’ he will very often lie down. To him, ‘sit’ might mean get lower, go down toward the ground.”
Many people tend to overestimate their dogs’ facility with words and assume that dogs and humans have a shared understanding. Because a dog responds in one context and not in another doesn’t mean he is being disobedient. As Tom Brownlee, master trainer with the American Society of Canine Trainers and instructor in Carroll College’s anthrozoology program, candidly advises owners, “If a dog’s not getting ‘it’ — whatever ‘it’ may be — then you are doing something wrong. It’s our job to help them understand.”
When you talk to your dog, consider that the words you speak might not carry the same meaning for both of you. Instead, other aspects of communication might be more relevant. Maybe the real lesson is that context, prosody and tone — rather than dictionary definitions of words — are vitally important for human communication, too.
This piece is dedicated to Professor César Ades (1943–2012) and Dr. Penny Bernstein (1947– 2012). While their exceptional contributions to the fields of animal behavior and psychology endure, their presences are greatly missed.
News: Guest Posts
Study finds Hormone-disrupting Chemicals Leach from Some Plastic Toys
The toy aisle is meant to be all about fun, but recalls, toxic imports and a dearth of regulations have left dog owners facing tough choices. Many toys are made of plastic and may contain chemicals that interfere with hormones.
A new study by researchers at the Institute of Environmental and Human Health at Texas Tech University shows that BPA and phthalates, chemicals that disrupt hormones, “readily leach” from plastic or vinyl bumper toys used to train retrievers.
Philip Smith, a toxicologist and co-author of the as-yet unpublished study, uses plastic bumpers to train his Labrador Retrievers, Bindi, age 11, and Huck, age 5. He wondered if the bumpers might expose them to hazardous chemicals.
In fact, the compounds are hard to avoid. BPA, the building block of polycarbonate plastic, is found in most food and drink cans; phthalates are common in food packaging, personal care items and vinyl plastics.
“BPA and phthalates come from many, many sources” besides pet toys, Smith says. So a dog’s “cumulative exposure may be significant.”
The study, conducted by graduate student, Kim Wooten, is one of the first to examine these chemicals in pet toys. In children’s toys, some phthalates have been banned in the U.S. and the European Union. In July 2012, the U.S. Food and Drug Administration banned BPA in baby bottles and children’s drinking cups.
Although their health effects in dogs are unknown, the hormones they interfere with regulate many biological functions.
Studies done mostly with rodents have linked BPA and phthalates to impaired development of reproductive organs, decreased fertility, diabetes and obesity, cancers, and behavioral and attention problems.
No, dogs are not mice. There are “species sensitivity differences” in regard to toxics, Smith says. For example, dogs are at greater risk than humans from eating chocolate. But while their sensitivity to synthetic chemicals may also differ, “we are unaware of specific reasons why they might respond in a significantly different manner.”
Available data suggests that the most vulnerable pets may be pregnant females “and perhaps young animals like puppies.”
According to a 2012 pet health report by Banfield Pet Hospital, some cancers and other diseases in dogs are increasing. “The rate of overweight and obese pets has reached epidemic levels in the U.S., affecting approximately one in five dogs and cats.”
The causes are unknown, but Smith says it’s possible that endocrine-disrupting chemicals, including phthalates and BPA, play a role.
Certain aspects of canine cancer suggest that dogs are sensitive to them, he says. For instance, exposure to estrogens raises the risk for mammary cancers. For metabolic disorders such as obesity and diabetes, researchers are finding that some hormone-disrupting chemicals appear to “affect metabolic endpoints, in addition to reproduction and behavior.”
For the toy study, the researchers tested orange and white bumpers from two unidentified makers, using artificial saliva to simulate a dog chewing a bumper. The amount of toxics released in a dog’s mouth couldn’t be determined due to the use of simulated saliva,
But what is a high exposure in dogs?
“We are not aware of any exposure guidelines pertaining to these particular chemicals and dogs,” Smith says.
They suspect the levels released from the bumpers would be very high, though, compared with children’s toys.
The study also examined BPA and phthalates from ordinary plastic pet toys sold in stores. The bumpers leached more, but the results suggest that the other toys might have released other hormonally-active chemicals.
Smith highlights the uncertainty that shoppers face, saying the bumpers might have been made from different materials, or perhaps the packaging limited the release of some chemicals before the experiment.
Or, the less affected toys may have involved “materials that are also used in the manufacture of children’s toys.”
“We’re not really sure, but intend to pursue the question further.”
Good thing for pet owners.
“Given the extent of plastics in the human-canine environment,” Smith says, avoiding the chemicals entirely may not be possible.
But not all plastics are the same. When it comes to leaching of chemicals “each type is very different.”
“That is why studies on individual products are important.” Pet owners need the information “to make thoughtful decisions.”
Some pet toy makers say they use BPA-free plastics.
But owners may wonder why it’s even a question. Why should they have to worry about chemicals in toys or migrating from cans, even into “organic” food, to add to their dog’s exposure?
At least—at last—it is being studied.
Smith’s team plans to continue studying the exposure of pets to chemicals. “We think there is a great deal to be learned about potential pet and human health impacts from chemicals in the environment,” he says.
And as they learn, Smith says they hope to yield the data needed “to inform decisions about how we manufacture pet products, which ones we buy, and what we allow our pets to chew.”
Good Dog: Studies & Research
The Beauty of Diversity
For those of us who love dogs, using DNA tests to deconstruct our mongrel pooch’s mysterious heritage is appealing because we want to be able to answer the question, “What kind of dog is that?” Companies say that DNA-based diagnostic tests, which sell for about $60, can answer the question by comparing your dog’s DNA to over 100 of the most popular breeds. But are the tests accurate? I decided to find out.
Chance, a 10-year-old mixed-breed dog who has lived with me for six years, was my guinea pig. I tested his DNA using three different tests. In 2008, when I wrote the prequel to this article (read it online at thebark.com/dna), I had his ancestry tested with the Canine Heritage Breed Test. At that time, the company used 96 markers and tracked them to 38 breeds. A marker is a gene or DNA sequence on a chromosome that indicates “breedness.” The labs claim that the markers they use are 99 percent accurate.
In May 2012, when I began doing research for this follow-up article, I tested his DNA with the amplified Canine Heritage Breed Test again because it had been substantially improved to 400 markers and 120 popular breeds. I could have paid $25 to upgrade the 2008 test. But to be fair in my test-of-the-tests experiment, I submitted his cheek swab under a different name and without a photograph, just in case, as many people believe, the tests are a scam. In addition, I used the MARS Wisdom Panel Mixed Breed Identification Test. Mars looks at 321 markers and includes 185 breeds in its database.*
To analyze and compare the results fairly, I needed to find out if the tests were processed the same way, and I researched the history of the breeds identified in Chance’s ancestry.
Comparing the Tests
If a primary parent breed can’t be identified in the DNA, the program will look for a secondary grandparent breed, and so on and so forth, until it eventually clusters with a distant breed (if there is one). If there are no purebred ancestors, remnant breeds will be sought.
To identify markers that characterize a breed, labs take samples from multiple thousands of individual dogs representative of more than a hundred breeds. However, those dogs differ from one laboratory to the next. Although their sample sizes are big enough to absorb minor differences, no two dogs are exactly alike. Plus, line-bred dogs can affect results. For example, Labrador Retrievers bred exclusively for hunting may be more like each other than they are like the breed.
Finally, descriptive terminology differs. Canine Heritage uses primary, secondary and in the mix. Wisdom Panel uses parent, grandparent, great-grandparent and next best breed matches that include percentiles.
Because Chance has no purebred parent, his strongest signal would come from a purebred grandparent. One test indicated a Siberian Husky grandparent. However, the other two tests claimed he has no purebred parent, grandparent or great grandparent. In any case, all three tests concur that a combination of spitz breeds provides the strongest signals in Chance’s ancestry — Siberian Husky, Alaskan Malamute and, to a lesser degree, the Pembroke Welsh Corgi, a breed with some spitz lineage. Although it transmits a faint signal, the Pembroke Welsh Corgi is the only breed that showed up in more than one test. The white German Shepherd and blackand-tan German Shepherd, strong and weak signals respectively, are both named as ancestors and are admixtures of one another. Although they are herding dogs, it’s probable that both breeds have some spitz lineage. The Japanese Chin, a miniature Asian breed derived thousands of years ago from larger mastiff and spitz dogs, is also a fairly strong signal.
Large terriers make up the next strongest signals in his DNA. The German Pinscher, Standard Schnauzer and Doberman Pinscher are closely related. German Pinschers were used to develop the relatively new Doberman Pinscher breed. The Standard Schnauzer, originally called the Wire-haired Pinscher, is directly related to the German Pinscher. Sight hounds are mentioned in two tests. In the late 1800s, Borzois were likely mixed with Huskies to increase speed, and terriers were mixed with Italian Greyhounds.
The weakest signals, in some cases less than 2 percent of his makeup, include a ragtag group of breeds, including Border Collie, English Setter, Cocker Spaniel and Leonberger.
Making Sense of the Findings
The ancestral breeds named in the three tests seem absurdly disparate, but they are not contradictory. They all point to one truth: only a few degrees of separation differentiate Chance from all modern breeds. This is because most purebred dogs have a crippling lack of genetic diversity, which is the unintended consequence of modern breeding practices.
Except for 14 ancient breeds — Afghan, Akita, American Eskimo, Basenji, Canaan Dog, Chinese Shar-Pei, Chow Chow, Dingo, Finnish Spitz, New Guinea Singing Dog, Saluki, Samoyed, Shiba Inu, and Siberian Husky — all our modern breeds were developed in the last few hundred years.1 Although each has its own DNA fingerprint, they have so little genetic diversity that if you go back far enough, the DNA of almost every dog, mixed breed or purebred, will cluster with a few common ancestors. This finding raises the question, “How can breeds that look so different be so closely related.”
The complex DNA of stray mutts on the mean streets of, for instance, Lugazi, Uganda, or Zorzor, Liberia, may answer the question. Ubiquitous freeranging dogs living on the fringes of human settlement are not, as previously believed, semi-feral, mongrelized purebred dogs, but rather, are genetically distinct and subject to the pressures of natural selection. Some populations have been isolated for hundreds, if not thousands, of years. Subsequently the village dog genome remains complex and unabridged.
Suspecting that village dogs may be pure genetic remnants of ancient dogs, Adam Boyko, assistant professor in the Biomedical Sciences Department at the Cornell University College of Veterinary Medicine, co-founded the Village Dog Genetic Diversity Project with his colleague Carlos Bustamante, a genetics professor at Stanford School of Medicine.
The project is a worldwide collaboration of researchers, volunteers and veterinarians who gather canine DNA samples along with photos and information on weight, age, body measurements and coat color. The samples are analyzed at the Canine DNA Bank at the Baker Institute for Animal Health, part of Cornell’s College of Veterinary Medicine, which maintains a growing DNA archive of dogs worldwide.
The scientists believe their work will shed new light on when, where and under what conditions dogs were domesticated, and how dogs have adapted to human settlement, environmental stress and disease.
The first phase of the study included collecting samples from modern breeds, their mixed-breed relatives, breeds reputed to be from remote regions of the world and African village dogs. In 2009, they reported that African village dogs are a mosaic of indigenous dogs descended from more ancient dogs that migrated to Africa.2 Findings also indicated that their genome is being eroded at an alarmingly fast rate as they mate with recently introduced modern dogs. Researchers are now scrambling to find dogs in even more remote locations. In the summer of 2012, workers began collecting DNA samples in Liberia and the Democratic Republic of the Congo.
On a continuum, gray wolves, the progenitor of all dogs, have the most genetic diversity, and purebred dogs have the least. Village dogs’ diversity lies somewhere in between. Because purebred dogs are the result of strong selection for exaggerated traits, they have only a fraction of the genetic diversity displayed by village dogs. The genetic variant that underlies a desirable trait, whether it’s extreme size or intense behavior, has become fixed, wiping away not only competing variants but also variants associated with nearby genes.
Genes located close to each other on a chromosome are said to be linked, and tend to be inherited together or, conversely, wiped away at the same time. Thus, a trait that isn’t selected for can be wiped away simply as a result of being in the wrong place at the wrong time. If that trait happens to affect, for instance, immune response to disease, then that could be a problem.
By comparing the genome of village dogs to that of purebred dogs, scientists hope to be able to identify what’s been lost as a result of intense artificial selection. Dr. Boyko notes that “village dogs offer a chance to understand the mechanisms of certain genetic diseases. Knowing what those genetic variants are might be the first step towards invigorating genetic diversity in some modern breeds.”
The Significance of Canine Origin
Previous studies suggest that dogs originated in places as varied as Eastern Europe, China’s Yangtze River Valley and the Middle East. In a 2002 study, researchers pinpointed East Asia as the place of origin. However, some scientists think these dogs are descendents of an even older population that developed in a different place. Dr. Boyko’s findings confirm this. African village dogs have about the same amount of genetic diversity as those in the East Asian study, suggesting that both groups are the same age. It’s possible that both populations originated together somewhere else and then migrated to East Asia and Africa at about the same time.
To thoroughly complicate matters, the Canidae family does not play by the same rules as most other mammalian families. Unlike, say, horses and donkeys, dogs, wolves, coyotes and golden jackals can interbreed and produce fertile offspring. Consequently, following the genetic trail from domestic dog to wolf leads to a lot of stops and starts and many dead ends as well as plenty of headaches for evolutionary biologists.
A Multi-Disciplinary Approach
As Dr. Larson notes, “There has been so much admixture since dog domestication began, and especially in the last few hundred years, that looking at modern dogs is always going to be problematic. There may be modern populations that are less ‘corrupted’ or admixed, but even they will possess a legacy of several thousand years of crosses with large numbers of populations, and even wolves.” He adds, “The only way forward is to focus on other methods, including, but not limited to, ancient DNA from archaeological dog and wolf remains. And of course, there is the wider interpretation and understanding from lots of other fi elds to put it all in context.”
In the paper, researchers discussed an interesting pattern that emerges when sites with archaeological dog and wolf remains are overlaid onto maps showing the historical distribution of wolves. First, the archaeological remains are not found in the places where ancient breeds are believed to have been developed, intimating that dogs may have been domesticated multiple times from local wolf populations. Second, most of the ancient breeds come from areas where wolves never ranged, suggesting that humans had dogs as they migrated around the globe. Furthermore, dogs only appeared in these locations after agriculture was introduced.
The canine genome’s full story continues to evade scientists, but as DNA technology advances and analysis becomes cheaper and faster, researchers are optimistic that the answers they seek are right around the corner.
Will I continue to test my future shelter rescue mutts to find out who they are, even though I know that the answers will be the same — all modern dogs are so closely related that it’s almost impossible to discriminate ancestry? Probably. Other mysteries lie hidden in our dogs’ DNA. The idea that an animal can be morphed into so many extreme shapes and behaviors yet remain a simple combination of only a few stem parents is one of them.
We like to believe that scientific discovery advances tidily, fact by fact, to prove an irrefutable truth. But science is a messy business. And there is hardly a better example of just how messy than the search to tease out the mysteries hidden in the canine genome.
Good Dog: Behavior & Training
Dogs walk again after spinal injury
In an exciting development in the treatment of spinal cord injuries, researchers at Cambridge University were able to restore some movement to the legs of dogs who had been paralyzed. (All 34 dogs in the study had become paralyzed by injuries or accidents. No dog was purposely injured for the research.)
The breaks in the spinal cord were at least partially fixed with the use of cells from the dogs’ own noses. The specific type of cells that they used, olfactory ensheathing cells (OECs), are involved in the growth of nerve fibers that are necessary for communication between the brain and the nose.
Dogs who were treated with OECs showed significant improvement in the movement of their back legs compared with the control group, which did not receive OECs. Being able to walk again obviously has considerable quality-of-life benefits. Researchers point out that this procedure will probably be most effective if combined with other therapies, such as drugs and physical therapy.
Though it is likely a long way off, similar therapies may eventually be effective in treating people with paralysis because of spinal cord injuries.
Wellness: Health Care
Something was wrong with Whiskey, and it wasn’t lethargy, whining or refusal to eat that tipped off his owners. It was chew sticks, unchewed. For the 10-year-old Small Munsterlander, chewing was a lifelong obsession. It had been a good life, one spent running down San Francisco city sidewalks; playing in the parks; exploring neighborhood shops; and, of course, chasing toys on the beach.
Whiskey’s owners, Tom Swierk and Robin Addams, indulged his appetite for beef tendons and other treats. The dog they had acquired as a young pup still had “lots of sass,” as Swierk describes him, or he did until last Thanksgiving, when his owners realized he had lost interest in chewing, one of his favorite pastimes. The Small Munsterlander, a hunting breed that originated in Munster, Germany, has been bred for centuries to thrive on chasing and retrieving. True to his roots, Whiskey was a friendly, devoted dog with an intense streak that his owners channeled into play. When Whisky ignored his chew toys, Swierk thought it was a problem with a tooth, and took him to the vet.
It was cancer.
Oral cancer, both malignant and benign, is not uncommon in dogs. Unfortunately, Whiskey’s tumor wasn’t benign. The lesion on his lower left gum was malignant squamous cell carcinoma, the second most common oral malignancy in dogs. In humans, it accounts for 70 percent of all oral tumors.
The wrenching news came with a silver lining: the cancer hadn’t spread to other organs. “This type of malignant tumor metastasizes less than 10 percent of the time,” Swierk says. It is known for its aggressive growth, however, and the tumor had already invaded Whiskey’s jawbone. Nearby were lymph nodes, a ready target and a pathway for the cancer to spread.
What, then, could be done? The usual course of action was to amputate the affected bone, sometimes using chemotherapy and radiation. Another common treatment involved shaving the growth, Swierk says, but that would also mean subsequent periodic surgeries. With the diseased bone removed, Whiskey’s chances for a full recovery were good. A life without chewing, however, wasn’t so promising.
After amputation, the jaw is never quite the same. The teeth and bones gradually fall out of alignment, and the dog’s teeth can cause ulcerations in the hard palate. He could eat, but there would be no more chew toys. He could not play ball or tug of war.
As it turned out, there was another option. A team of vets at the University of California, Davis, had been working on a fix for pets who lost jawbone to disease or injury. It had only been used in five other dogs, but the results had been good. Their vet referred him to the UC Davis School of Veterinary Medicine, 73 miles east of San Francisco.
It was a done deal for Swierk and Addams, who were prepared to travel to New York, if that’s what it took to not only save their dog, but have him back whole, and to pay the $8,000 treatment cost. Whiskey was more than a pet to them — he was their companion.
“Whiskey is our world, plain and simple,” Swierk says.
Bone regeneration was seen as science fiction in 1948, when Dr. Marshall R. Urist, a UCLA orthopedic surgeon who pioneered the field, got started. Urist spent five decades at the bone research laboratory at UCLA, where he discovered how to use proteins to stimulate skeletal repair.
In 1971, he proposed the name “bone morphogenetic protein” (BMP) for the growth-promoting factors he used to prompt new bone growth in rabbits. The bone proteins act as signals to stem cells, which migrate to them and are converted into bone-forming cells. These cells then grow bone in the area where the BMP was placed.
Naturally occurring BMP is found within bone, but clinically useful amounts can’t be easily extracted from human donor bone and so must be genetically engineered in the lab.
At UC Davis, Whiskey was in the care of a team of vets who had been perfecting a new procedure to regrow damaged jawbone, work that drew on Urist’s research and other experimental and clinical treatments developed for humans. The team included Dr. Dan Huey, a biomedical engineer; Dr. Boaz Arzi, a veterinary surgeon; and Dr. Frank Verstraete, who heads the dentistry and oral surgery service at the veterinary teaching hospital. Their goal was to put biomedical approaches to bone replacement to use in veterinary practice. Once they had refined a technique that would work for dogs, they put out the word, and soon referrals from other vets were coming their way.
“It wasn’t an experimental study, just an innovative application of existing materials,” Verstraete says.
Over a two-year span, eight dogs have undergone the procedure, and to date, all are doing well, the vets say. Each dog spent three days at the teaching hospital for an exam, surgery and recovery, followed by three post-operative exams.
Whiskey, their sixth patient, had the largest lesion. There was no getting around it: he would lose much of his jaw. But with the help of a titanium plate, a sponge and some bone proteins donated by Pfizer, he would grow a new one in a matter of months.
The team’s first task was to decide how much bone to take in order to remove all of the cancer. That proved to be 2.5 inches, or about half of Whiskey’s lower left jawbone. Once the diseased bone was out, in went a titanium plate built by Dr. Arzi, which was screwed into place on the remaining bone.
But the titanium plate alone was not enough to hold the jaw together. The greatest risk was failure of the plate due to the large gap where the bone had been, Dr. Verstraete says. Over time, pressure on the plate would cause the surrounding bone to resorb.
Enter the scaffold: a stiff, sponge-like piece of material that was fitted into the space. It, too, was only part of the solution. The next step in building a new jaw would require Whiskey’s own stem cells, attracted to the bone proteins in which the scaffold had been soaked. Like a magnet, the bone proteins would draw stem cells from the dog’s surrounding bone and soft tissue to the scaffold, where they would attach and turn into bone cells, according to Dr. Huey. The new bone cells would eventually fill the entire void and integrate with native bone. On a molecular level, the new bone is the dog’s own, with a DNA makeup identical to other bones in his body.
There is no need to match the proteins to a particular dog, Verstraete says. “The BMP we use is synthetic, recombinant human (rhBMP-2). It doesn’t elicit any antibody response in experimental animals.”
Just as the vets borrowed from human medicine, their procedure for dogs will now find its way back into human medicine. Their success with the eight cases has given them material for a report on the work, which they plan to submit to a scientific journal.
What lies ahead for the promising surgery? The vets hope to be able to modify the technique for use with larger jawbone defects in animals. Also on the horizon: human arm and leg bones. There is more work to be done, however. “The technique that we used has not been done for weight-bearing bones yet,” Verstraete says.
Is the new method a cancer cure, or a quality-of-life issue?
“Both,” Verstraete says. “We only do the surgery for tumors that haven’t spread. Reconstruction greatly improves the quality of life compared to the previously used technique.”
Swierk knows there’s no guarantee that Whiskey will remain cancer-free. “The assumption is that it’s a cure, but the verdict is still out.” But based on Whiskey’s September checkup, it’s “so far, so good.”
Swierk says the bionic jaw is doing its job. “He eats all his yummies as he did before.” In addition to munching kibble, caulif lower and chew sticks, he’s back to chewing and chasing balls and toys. Swierk isn’t surprised that their dog has bounced back, or that the new technology was available right when he needed it. “We never doubted for one minute that Whiskey would succeed with this new cutting-edge surgery.” It’s all part of Whiskey’s good nature, Swierk says.
“He’s led a charmed life.”
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