Jane Brackman, PhD, is an authority on the cultural history of canine domestication and the author of two books on pets in 19th-century America. See her new pup, Barkley, and watch him grow on her blog.
Culture: Science & History
What can archeology tells us about the “connection” origins.
May 20 2016
Studies of prehistoric dog burials have been making splashy headlines lately. Although the popular press would have us believe that these finds are proof of the affectionate relationship our ancestors had with dogs, the unifying theory that gives meaning to burial patterns remains elusive because ancient people left no written record.
What little we know about dogs’ social roles in antiquity is a patchy mosaic of information derived from physical analysis of bones excavated from gravesites. The accuracy of this mosaic has been further complicated by archaeologists’ long-standing difficulty with reliably distinguishing between wolves and dogs, not only because the two animals look similar, but also because changes in morphology during the early stages of domestication were subtle.
However, in 1986, zooarchaeologist Darcy Morey, now adjunct professor in anthropological sciences at Virginia’s Radford University, developed a statistical equation to more accurately identify dissimilarities between skulls. A decade later, geneticists were able to extricate even more conclusive information from DNA. Then, in a landmark paper published in 1999 in the Journal of Heredity, geneticists Carles Vilà, Jesus Maldonado and Robert Wayne suggested that the first domestication event occurred more than 100,000 years earlier than dog burial remains suggested. This marked the beginning of a decades-long trend that all but excluded archaeology and other academic disciplines from the equation.
Morey—and later, Greger Larson, evolutionary biologist in Durham University’s Department of Archaeology in the UK—challenged the exclusive use of DNA analysis to identify the time and place of the first domestication event. They advocated a return to a cross-discipline approach that included traditional archaeology, DNA analysis, isotope geochemistry and radiocarbon dating in the context of environmental sciences such as paleoclimatology and biogeography.
Robert Losey, associate professor of anthropology at the University of Alberta, is among the scholars who agree with this approach. “When the genetic information can be integrated with information on dogs’ diets, diseases, activity patterns and archaeological context, we get a much more complex and informative picture of people’s emotional and day-to-day lives with their animals than we can through genetics alone.”
Siberia’s Lake Baikal, the largest and oldest freshwater lake in the world, is known for its well-preserved Middle Holocene (3,000- to 9,000-year-old) hunter-gatherer cemeteries, which attract scientists studying how social and environmental pressures influence long-term cultural change. Leading a team of researchers from various disciplines, Losey analyzed numerous Lake Baikal sites containing human, dog and wolf remains dating back 5,000 to 8,000 years; the team’s findings were published in 2011 in the Journal of Anthropological Archaeology.
As he explained, “What I tried to do in my study was to approach these dog skeletons just like we would a human skeleton. We applied a suite of analyses in order to tease out the interesting and relevant details of their lives. The best way to fully understand the domestication of dogs is to use as many forms of evidence as possible, and to employ a wide range of specialists.” Their interpretive model was partly based on ethnographic records of indigenous groups from across the northern hemisphere. For example, many northern people, who have an animistic understanding of their world, strongly believe that animals, plants and inanimate objects possess souls.
Using stable isotope analysis, researchers determined that dog and human diets were the same. In comparison, a wolf found buried in the same area had foraged on large game, a diet different than that of local people. Some dogs were buried with artifacts the dog would have used or been familiar with during its life: a decorative collar-like pendant made with red-deer teeth, a round ball-like stone, spoons, antlers and other implements.
Bone-wear suggested that the dogs had worked alongside people, likely as transport animals hauling heavy loads. Some had recovered from injuries that would have required special care. People and dogs were buried near one another in the same cemetery, and in some cases, were buried together (in one instance, a man was buried with two dogs, one on either side). Analysis of the dogs’ skeletons revealed a resemblance to modern-day Siberian Huskies, although they would have been larger. Genetic work on the specimens confirmed an ancestral link to our modern dogs.
According to Losey, “I think what we are really looking at is a set of relationships between people and dogs, and to study relationships, we need to try to understand the life histories of animals, not just their evolutionary history.”
Putting all of the small parts together, the researchers painted a big picture. They suggested that ancient indigenous people considered some dogs to be very special. Unlike the majority of simpler animals, whose spirits collectively recycled after death, these dogs were thought to be like humans, with powerful and unique souls that required mortuary rites similar to those of deceased people.
This special treatment was necessary for both dogs and humans so that their souls could return in new individuals. Losey added, “I think the act of treating a dog as a human upon its death indicates that people knew it had a soul, and that the mortuary rites it received were meant to ensure that this soul was properly cared for. These practices also clearly indicate that people had close emotional bonds with some of their dogs, and perhaps mourned their loss like they did [the loss of] their own family members.”
Waves of Proto-domestication
Although romanticized images of digs in the shadows of ancient civilizations continue to feed the popular notion of archaeology, a more accurate but less dramatic scene would have scientists in white lab coats conducting microscopic analyses of polymorphic nucleotides extracted from bone remnants stored for many decades on museum shelves. Indeed, bones unearthed long ago have proven to be quite revelatory. The most unexpected discoveries regarding the human/dog relationship are based on analyses of materials extracted from canid bones excavated, catalogued and archived in 1873 and 1884, respectively.
The oldest skull, which dates to 31,700 years ago, was found at Belgium’s Goyet Cave. Another from a site in Predmosti in the Czech Republic proved to be about 27,000 years old. One skull from the Predmosti site had a mammoth bone fragment in its mouth. Does it indicate that a special connection had developed between people and dogs as far back as 30,000 years ago? Archaeologist Mietje Germonpré of the Royal Belgium Institute of Natural Sciences—lead author of the two papers describing the 2008 and 2012 research results—said, “I believe that the dog skull with the bone between its teeth suggests some sort of ritual treatment. The position of the bone fragment in the mouth suggests that it was inserted between the incisors of the dog post-mortem.” The ethnographic record indicates that placing body parts between the teeth of dead carnivores was a common practice in many cultures. Exactly why remains open to speculation.
Paleoanthropologist Pat Shipman, who has written extensively on the evolutionary impact of the human/animal connection, suggested that the mammoth bone points to a cross-species alliance that may have developed even earlier—one that might account for the success of our early ancestors. She hypothesized that proto-dogs, like those found at the Predmosti site and at Goyet, cooperated with humans in a symbiotic hunting partnership that could account for the significant and abrupt increase in the number of animals found at mammoth kill-sites dating as far back as perhaps 45,000 years. The initial domestication of dogs may have been accidental, but once humans realized the value of these living “tools,” they began to refine them for increasingly specialized purposes.
In a separate study, a group of researchers led by Ole Thalmann examined ancient DNA of Eurasian dogs (the Predmosti dogs had not been genotyped) along with others, and came up with some surprising results. Separated by only a few thousand miles and a few thousand years, the ancient dogs were not related to each other, nor were they related to modern dogs. In addition, none of the lines survived, which suggests that domestication experienced many starts and stops in different regions with different wolf populations. Scientists speculated that the last ice age, which began about 26,000 years ago, might have contributed to this stutter-step process. They also found that living dogs are more closely related to ancient, extinct wolves than they are to modern wolves.
If domestic dogs somehow catastrophically died out, would we have the natural resources needed to recreate them? In Shipman’s opinion, “The answer is both no and yes. If dogs disappeared, they probably couldn’t re-evolve from the wolves we have now. But those extinct wolves evolved into contemporary wolves, and canids in general have a huge amount of variability in their genomes, which is why we have so many different types of dogs today. If by ‘dogs,’ you mean a highly variable canid that can live with and cooperate with humans, then I think the answer is yes. Would it be the same dog as today? We can’t be sure.”
Laid to Rest with Care
In the past two decades, archaeologists have unearthed the remains of about 1,400 dogs buried 2,500 years ago on prime ocean-view real estate in ancient Ashkelon, today a thriving city located on the Mediterranean Sea, 30 minutes from Tel Aviv. The dog burials spanned a period of eight decades. Carefully positioned alone in shallow pits, the dogs’ bodies were placed on their sides, legs flexed, tails gently tucked around their hind legs. Ranging in age from newborn through elderly, they appear to have died of natural causes.
Ashkelon is only one of thousands of ancient dog-burial sites scattered across the globe, and its large number of burials raises the question, “How many dogs were buried in antiquity?” The answer is, “We’ll never know.” Throughout prehistory, people mostly disposed of bodies, human and non-human, in untraceable ways; they sent them floating down rivers or buried them in shallow earthen graves—reverent practices that lost them to the ages.
In addition, dog burials were so common that they are field sites’ most overlooked artifacts. In her 2009 manual, A Practical Guide to In Situ Dog Remains for the Field Archaeologist, Susan Crockford, adjunct professor at the University of Victoria in Canada who has worked with dog remains for more than 20 years, maintains that far more dog burials are encountered than are ever mentioned in archaeological site reports. Workers aren’t properly trained to recognize dog remains, nor do most understand the history of dogs and their significant contribution to the human story. Consequently, much of what we could have learned about the human/dog connection has been lost forever.
Furthermore, scientists can’t develop statistical estimations because it’s unclear whether or not dog burials are representative of the total dog population. However, by calculating the timing of genetic bottlenecks, Thalmann and his colleagues suggested that ancient dog populations paralleled the trajectory of human population growth. Dog numbers increased steadily until about 5,000 years ago, then abruptly declined, followed by a sharp increase 2,500 years later. Even if their calculations are proven accurate, whether (and why) certain dogs were selected for burial while others were not remains unclear.
The first comprehensive review of dog burial studies, “Burying key evidence: the social bond between dogs and people,” by Darcy Morey, published in the Journal of Archaeological Science (2006), put the documented cases and site locations in perspective. Written for a scholarly audience but with enough humanity to appeal to lay readers, the paper brought new attention to a topic of inherently widespread interest. Given that so many burials are untraceable and others are uncertain, why even suggest a total?
Professor Morey said, “Depending on circumstances, for a given site, I think it’s possible to suggest how many were buried, at least in that place.” In a later book, Dogs: Domestication and the Development of a Social Bond, Morey included an appendix that inventoried dog burials, including totals as known from specific places. “But,” he added, “given frequent uncertainties, I think in general that suggesting combined totals is fraught with problems.”
As companions and helpers, dogs hold a special place in our hearts, and increasingly, as our equals in relation to our place in the collective physical world. Mary Elizabeth Thurston, author of The Lost History of the Canine Race, anthropologist and historian for Hartsdale Pet Cemetery in Westchester, N.Y., said, “Fifteen years ago, about 55 percent of the public believed pets deserve mortuary rites in death. Today, the number is much higher.”
Thurston also noted an uptick in the number of people who wanted to be laid to rest with their animal companion, either by arranging for their own cremated remains to be buried with the pet, or for the cremated remains of that animal to be interred with them. “When animals fill an innate need for companionship as either surrogate children or life partners, they become truly indispensible in the eyes of their human caretakers. The desire to be together is understandable. The grief felt at the death of that pet is profound, and people want to accord their animals a measure of respectful remembrance in death, just as [they] would any other family member. However, we can’t assume that ancient people, who left no written records, held our same modern sensibilities.”
Canine remains in ancient human burial pits more often indicate that the dog was part of an offering, sacrifice or spiritual ritual rather than a companion. Thurston suggested that the ancient interment of single animals with grave goods, especially things that the dog used in life, along with evidence that shows the dog died of natural causes, might suggest an affectionate relationship and the belief that the animal had a soul—that, like people, it would need these things on the “other side” for a good life.”
In “Peru’s Mummy Dogs,” writer Roger Atwood noted that in 2006, Sonia Guillén, archaeologist at the Maliqui Center in Ilo, Peru, reported that her team had discovered 40 dogs buried about 1,000 years ago in separate plots alongside the remains of what were probably their owners. The discovery was unusual in that the dogs were interred with items that look like toys and food. As Guillén, who studies Peru’s Chiribaya culture (which pre-dated the Incas), told the press, “We have found that in all the cemeteries, always, in between the human tombs, there are others dedicated to the dogs, full-grown and puppies. They have their own graves, and in some cases they are buried with blankets and food.” Guillén, who suspects that the dogs may be direct ancestors of the companion and working dogs who populate the village today, is collecting DNA for future study.
Most human/dog burials occurred 5,000 to 8,000 years ago in hunter-gatherer societies and disappeared with the beginning of the agrarian era. But their absence doesn’t equate to a lack of an affectionate human/dog connection. At the Lake Baikal site, when pastoralists inhabited the area beginning about 5,000 years ago, they did not bury dogs, at least not in areas where archaeologists might find them. According to Robert Losey, “The difference between the pastoralists and the hunter-gatherers living in this area of Siberia is that the hunter-gatherers buried some of their dogs in cemeteries used otherwise for the human dead. The pastoralists do not appear to have done this.
“Over the past few years, my colleagues and I have interviewed local Buryat people, who are descended from some of these early pastoralists, about their dogs, and they clearly have a deep respect for [them], and do bury some of them. However, they are not considered non-human persons with individual souls, and in the local belief systems, are not spiritually equivalent with humans. So, they cannot be buried in local cemeteries. The best dogs, and the most loved ones, are given burial rites in some cases, but these tend to be elsewhere—on the tops of hills or mountains, for example. Some folks even recounted that they left pieces of meat in the graves with the dogs—food for them in the afterlife.”
As long as dogs have existed, they have been deliberately buried in every region they inhabited. Moreover, dogs have been buried more often than any other animal: singly, with other dogs, near people and with people. This ancient practice was a global phenomenon, one that crossed nearly all cultural boundaries. Precisely why dogs were buried may never be clearly understood, but the universality of the practice suggests it may be embedded in the human psyche and accordingly, is a fundamental part of the human/dog connection.
For in-depth information on sources cited click here.
Wellness: Health Care
On the trail of canine cancer
February 2 2016
In Dog Diseases Treated by Homeopathy (first published in 1863, before chemotherapy, radiation, biopsies and blood panels), author James Moore advised concerned dog owners on treating cancer: “An operation cannot remove the cancer, but it can remove the tumor, which causes much suffering; the knife is, therefore, merely palliative in its effect. Still, the disease, even then, is likely to return at a period more or less remote.”
Today, the diagnosis isn’t as bleak. Indeed, 50 percent of all canine cancers are curable if caught early enough. Moreover, the disease is mostly an aff liction of old age (tragically, some cancers strike dogs as young as two). It may seem like more dogs get cancer than ever before, but it’s presumably because they enjoy a longer life span, thanks to vaccinations against infectious diseases like parvovirus and distemper, and new treatments for congenital, degenerative and metabolic disorders.
“Cancer” is the broad term for a complex cluster of more than a hundred diseases. Although there are many causes, each type of cancer starts with alterations in genes that tell cells how to function, which triggers accelerated and uncontrolled cell growth. The defective signal may hide in abnormal genes inherited from parents, or germinate when normal genes are exposed to harmful environmental influences.
Some breeds are predisposed to certain types of cancer, and in those cases, a strong inherited genetic component is suspected. It is thought that a small number of genes account for cancer risk, but, although they are directly related to the development of individual cancers, rarely is a single gene the sole cause.
By the time people and dogs pass 70 and 10 years of age, respectively, about 50 percent will have been diagnosed with some type of cancer. The malady accounts for approximately 23 percent of all deaths in people. In dogs, cancer mortality varies across breeds, from under 10 percent to higher than 60 percent.
In general, small dogs weighing less than 20 pounds are at very low risk. (Small dogs have lower levels of IGF-1, a hormone that is related to bone and tissue growth. Researchers suspect this may be one reason they have a lower incidence of cancer.) For instance, the chance that a Chihuahua, Dachshund, Maltese, Miniature Pinscher or Pomeranian will get cancer is less than 10 percent. Breeds with the highest risk include the Bernese Mountain Dog, Bouvier des Flandres, Boxer, Bullmastiff and Golden Retriever (Fleming et al. 2011).
Goldens as Case Studies
Interestingly, cancer risk in Europeanbred Goldens appears to be significantly lower. A 2010 study put the mortality figure at 38.8 percent (Dobson 2012, Adams et al. 2010). Although much higher than average, the incidence is substantially lower than that found in North American Goldens.
Goldens in Europe and the U.S. may look similar, but there are enough DNA differences to separate the dogs into two distinct populations corresponding to their geographic regions. Gene pools on both continents are large, so breeding between the two populations is rare.
When studied in the lab, genomic differences suggest that risk for some types of cancer is related to recent genetic mutations in North American Golden Retrievers. And this could be good news: genetic differences between European and North American Golden Retrievers may be key to understanding the etiology of canine cancer overall.
Population, Popularity and Popular Sires
Registration agencies impose strict standards on pedigreed dogs, requiring that the ancestors of each dog be registered as well. This, combined with widespread use of popular sires, means that each breed is a closed population, with no gene flow. The “popular-sire” effect occurs when an animal with desirable attributes is bred repeatedly. Descendants share specific genetic mutations, both good and bad, and those mutations spread rapidly throughout the gene pool, where they may become permanently established, or fixed. (“Fixation” is a change in a gene pool in which at least two variants of a particular gene are reduced to only one.)
When the 1998 GRCA study confirmed that a high number of Goldens were dying of cancer, club members realized they had both a problem and an opportunity. The club’s nonprofit 501(c)(3) fundraising offshoot, the Golden Retriever Foundation (GRF), got off the ground about the same time the survey results were being analyzed.
It started by funding a few cancer studies, including some managed by Morris Animal Foundation (MAF), a nonprofit that invests in science to advance animal health worldwide. Eventually, GRF contributed $1 million and asked MAF to match it if both could agree on a project.
In the meantime, at a MAF canine cancer summit in Chicago, three goals were promulgated: build a tumor archive, fund more canine cancer studies and devise prevention strategies. In response to this collaborative effort, a team of scientists, epidemiologists, veterinary oncologists and surgeons, nutritionists, toxicologists, geneticists, breeders, and donors spent three-anda- half years designing the ideal study. Not an easy task.
Animal epidemiology studies (which deal with the incidence, distribution and possible control of diseases) are few in number, largely because they face so many obstacles. Among them are limited funding, participating private practices using non-standardized methods to record data, pedigrees that are difficult to confirm, and grieving owners who aren’t eager to authorize post-mortem tests. Some cancers are silent killers, so a sudden death may not be attributed to cancer. And, due to attrition, studies are difficult to adequately enroll and don’t last long enough to develop statistically significant patterns.
However, after almost four years of stops and starts, the Morris Animal Foundation Golden Retriever Lifetime Study, the first breed-specific, life-todeath research project of its kind, was launched on August 30, 2012.
Based on observations summarized in questionnaires, researchers hope to identify potentially modifiable risk factors that may account for the high incidence of cancer and other diseases in Golden Retrievers and, eventually, in all dogs. Funded and managed by MAF, the study will investigate the effects of genetics, nutrition and exposure to environmental factors.
Although other breeds are at higher risk for cancer, Golden Retrievers were chosen because their population exceeds that of most other breeds by a large margin: the larger the sample size, the more accurate the data. Additionally, because these versatile dogs perform multiple jobs—from assistance and search-and-rescue work to field, performance and companion tasks—they are subject to a broad range of environmental exposures.
Rodney Page, veterinary oncologist and director of Colorado State University’s Flint Animal Cancer Center and the project’s principal investigator, describes some of the factors underlying the study. “Within the estimates that we currently have, we know that 50 percent of canine cancers are curable with surgery and other treatments. Our study is addressing the ones you can’t cut out: the 15 percent of mast cell tumors that aren’t operable; lymphoma, a whole-body cancer; osteosarcoma and hemangiosarcoma, because they spread rapidly before they’re discovered. These four types of cancer cause approximately 80 percent of cancer deaths in Golden Retriever dogs.” These fatal cancers begin to increase in incidence around five to six years and peak about age nine or ten. However, they may also develop in dogs age two and younger.
More than 2,050 veterinarians are providing health care for enrolled dogs. Annually, they conduct physical exams and report findings online; collect samples of blood, urine, feces, hair and toenail clippings and send them to participating laboratories; submit health information from additional heath visits; collect tumor tissue samples when applicable; and provide owners with information and guidance to help them make a choice about necropsy (an autopsy performed on an animal) after the dog dies.
Participating veterinarian Stephanie Ensley of Bentonville, Ark., who enrolled her own Golden in the program, elaborated on the study’s intent. “The information we’ll gather looks at areas of potential exposure by air, contact and feeding. Owners are expected to provide information as detailed as chemicals used in the home, yard and on the dog, and drinking water sources, to name just a few. When all this information is put together and analyzed, we’ll have an opportunity to find commonalities that may be related to cancer and other diseases. The more data available, the more opportunity to find a connection. On the flip side, we’ll also find commonalities in dogs who live to be 15 and over.”
Among the study’s other expected outcomes are insights into how dog-breeding practices and lifestyle choices might be modified to reduce the prevalence of myriad diseases, and the creation of a repository of biological samples that may be made available to researchers working to develop genetic tests.
As GRCA research facilitator and breeder Rhonda Hovan, who has been a Golden Retriever advocate for 45 years, notes, “Breeders play a special role in the success of the study because they can recruit multiple siblings who share the same genetic heritage. Data from littermates who experience different environmental factors and diets during their lifetimes may provide unique scientific insights that could make a significant impact on the long-term health of dogs.”
One immediate benefit is that veterinarians, dog owners and dogs won’t have to wait until the study is complete to see results that may help influence and improve veterinary medicine. The questionnaire responses are analyzed quarterly, so information is continually streaming into the study, and trends, once validated, will be published as they emerge.
Genetic testing to eliminate dogs from the breeding pool may not be the panacea it first appears. Dogs share more the 300 inherited diseases with humans, from narcolepsy and hemophilia to diabetes and lupus. It’s unlikely that all of these can be bred away from while still maintaining healthy genetic diversity. Reducing diversity increases risk for other diseases to surface in the future, especially in a breed like the Golden Retriever, one that has already experienced diversity loss caused by widespread use of popular sires.
In an article published in Golden Retriever News (Nov/Dec 2014), Hovan cautioned Golden Retriever breeders: “Keep in mind that when we remove a dog from breeding due to a failed health test or for any other reason, we are removing all of that dog’s genes from the gene pool, not just the genes associated with disease or unwanted traits …” She also observed that rigorously removing dogs affected with minor conditions has far more potential to damage future generations than occasionally and carefully breeding them. Breeding away from targeted conditions, she says, is part of an inescapable loop that presents subsequent generations with an elevated risk of having some other problem arise. “When conditions are targeted without good cause, there’s an all-too-real possibility that the ‘something else’ will be worse than whatever it is we tried to breed away from to begin with.”
Eliminating dogs based on genetic tests is not a sustainable way to control disease. A better approach, Hovan explained, is to “test and replace” as opposed to “test and eliminate.” For diseases with a recessive mode of inheritance, breeders can avoid risk by breeding carrier and affected dogs to normal dogs. That way, the genetic variety represented by the line can be maintained for as many generations as it takes to arrive at genetically normal offspring.
As Hovan went on to say, “To make good decisions as caretakers of our breed, we need to know what we’re working with. You can’t change what you don’t measure.” To this end, GRCA is working with a research team from University of California, Davis, to survey the breed’s genetic diversity across types and geographic location, collecting samples from the U.S. and Canada. Referencing this survey, Hovan added, “We want to approach this in a scientific manner. This study will help to clarify what we need to do and provide a road map so we can move forward.”
Could one solution be as straightforward as avoiding environmental triggers that trip biological switches and activate uncontrolled cell growth? Maybe. Researchers expect to collect enough biological samples to accurately define the incidence of each cancer being studied. When the study ends, researchers will also have a detailed life story of every enrolled dog. The hope is that in the long run, data will show relationships between cancers and exposures.
The population-based study is creating a baseline for future research in all sorts of health-related issues. According to Page, “The samples and data we are collecting now will be used by scientists in the future to answer their own questions about health and wellness issues in dogs. Studies will be encouraged that access these assets for analyses of everything from toxic exposures to microbial populations in the gut as they might influence health outcomes.”
Cohort studies like the Golden Retriever Lifetime Study are costly, susceptible to attrition and take a long time to produce statistically useful information. Their value depends on an organization’s capacity to stay in touch and engage all participants. DVM, PhD and CEO of Morris Animal Foundation David Haworth, who also enrolled his dog in the program, summarizes it most concisely: “A study like this can only happen through the active participation of an extended community of dog owners, dogs, veterinarians and study sponsors. I think I can say with absolute certainty that we have one of the most active groups of study subjects of any longitudinal health study ever initiated. After all, they are Golden Retrievers.”
Wellness: Healthy Living
Investigating the microscopic worlds in our dogs may reveal pathways to better health.
July 10 2015
The microbiome is the invisible world of the hundred trillion bacterial, viral and fungal microbes that live on us and in us—on our hair and skin, behind our ears and inside our eyelids. The bulk of these miniscule microbes are good guys, gut microbiota that congregate in the digestive tract, where they bolster the immune system, manufacture vitamins and digest food to generate nutrients and energy.
Microbial equilibrium is a delicate balancing act, and a broad spectrum of inflammatory and autoimmune diseases is linked to having too many microbes—or too few. For example, researchers know that significantly lower bacterial diversity is found in both people and dogs with chronic inflammatory bowel diseases.
Teasing out the biological interaction of trillions of miniscule microorganisms that colonize the body, and the role they play in well being, is a new frontier. Will it be a watershed moment in veterinary medicine? Scientists are hopeful. The human microbiome has become a hot topic in biologic investigations, and canine research is fast catching up, much of it inspired by the success of the Human Microbiome Project, launched in 2007 by the National Institutes of Health (NIH). Using stool and tissue samples to isolate microorganisms, researchers are mapping the diversity and normal profile of the human microbial community.
Another undertaking, the Human Food Project, invites the public to submit personal and family microbial samples along with samples from family dogs to better understand how a person’s microbiome compares to that of animals living in the same environment. (The project’s dog segment has been discontinued.) The analysis centers on the anthropological co-evolution of humans, animal and plant microbes to understand modern disease against the backdrop of our ancestral/microbial past.
It’s all about dogs at Companion PBx, a new startup that primarily targets the canine digestive tract. Its goal is to build a cumulative gut flora database and develop dietary products customized for dogs’ digestive health. In January 2015, the company launched a Kickstarter campaign to raise money for construction of the database.
According to Companion PBx Chief Science Officer Kelly Scott Swanson, PhD, who’s on the faculty at University of Illinois, Urbana-Champaign’s Department of Animal Sciences, “By sequencing the microbes in your pet’s sample, we obtain a fingerprint of the microbial community in your pet’s GI tract.”
Microbes in Common
Affected by age, environment, ancestry, evolution, genetics and diet, microbial communities vary widely between species and across individuals within a species. A recent study suggests that our housemates—including the family dog—may also affect the composition of our personal microbial signature.
If you and your significant other kiss, hug and/or share a bed with your dog, the three of you have more in common than you think. A study conducted by researchers at the University of Colorado, Boulder, revealed several similarities: Adults who share a dog have more similar mouth microbes than those who don’t. Dog-owning families have more diverse and different microbial colonies than dogless households. Parents tend to share more kinds of mouth bacteria with their dog than they do their children. And children raised with dogs have a wider variety of microbes than dogless kids (Song et al. 2013).
Whether these spit-swapped microbes serve a purpose or are just passing through is not clear. But research shows that children raised with dogs are less likely to be afflicted by eczema (Epstein et al. 2010) and asthma (American Society for Microbiology 2012).
The notion that microorganisms in the canine gastrointestinal tract might have unique properties is not new. Early Romans understood the medical value of a well-run therapy dog program. Health temples, the ancient equivalent of modern-day outpatient clinics, were staffed with live-in cynotherapists, gentle dogs who wandered about the grounds greeting patients and licking wounds. Were the dogs healing only psychosomatic injuries? Time and additional research funding will tell.
The idea that our microorganisms may to some extent be collectively beneficial is intriguing. People and dogs have been exchanging microbes for at least 30,000 years, since the first little cave girl kissed the first proto-dog puppy smack on the muzzle. That’s a long history of sharing. It’s possible that our microorganisms are at least symbiotic, and perhaps even played a role in the dramatic domestication of the dog.
Theoretically, many thousands of years ago, a population of carnivorous wolves or ancient proto-dogs (depending on where you stand in the dog-domestication debate) transitioned from a meat-heavy diet to one laden with grain, a consequence of the agrarian revolution.
Scientists know that the acquisition of a new diet is a fundamental driver for the evolution of a new species (Dale, Moran 2006). When species transition from carnivorous to omnivorous diets, the gut microbial community co-diversifies with the host and drives further evolution (Ley et al. 2008). As human diets changed, so too did those of Canis familiaris. Over time, as we incorporated these unique animals into our daily lives, we continued to reshape them.
In humans, autoimmune and inflammatory diseases are on the increase. Scientists can’t verify a similar pattern in dogs because epidemiological studies are rarely conducted in veterinary medicine. Additionally, many autoimmune conditions are diagnosed based on the patient’s subjective description of symptoms.
But this is not the case with itchy skin. Dogs who scratch themselves incessantly are highly likely to have allergies. When researchers compared microbial colonies on the skin of healthy dogs to those of dogs with allergies, they found that non-allergic dogs have much richer and diverse skin microbial communities (Hoffmann et al. 2014).
But when it comes to proving causality, scientists wisely err on the side of caution. It’s not understood if a change in the microbiome causes certain conditions, or if it occurs as a consequence of the conditions. Nor is it absolutely clear that more diversity is better than less. At this point, scientists cannot say with confidence exactly what a healthy microbiome should look like in the dog.
Moreover, what seems logical may not be so. For instance, anyone who has lived with a poop-eating pooch has wondered why some dogs do and other don’t. Are coprophagic dogs seeking microbes lacking in their gut? Surprisingly, research involving mice suggests that this might not be the case; coprophagia in germfree mice is the same as in conventional lab mice (Ebino et al. 1987).
Other questions arise: Are the microbiomes of individual dog breeds more similar to each other than they are to those of other breeds? And could these isolated microbial communities drive breed-specific ailments?
Jan Suchodolski, DVM, a Texas A&M veterinary medical and biomedical sciences researcher who studies dog and cat gastrointestinal diseases, says that this doesn’t seem to be the case. As he noted, “So far, we do not have any clear evidence that gut microbiomes are more similar within breeds. Environmental influences such as age, diets and antibiotics, and especially the effects of GI disease, are larger than any breed effect.
“It may be possible that we missed an effect, as we have not evaluated thousands of animals. But if there were a breed effect, it would probably be very minor. Even within puppies of the same litter, the microbiome shows huge inter-animal variation, so the animal effect is much stronger than any other effect.”
Idiopathic canine inflammatory bowel disease (IBD) is a gastrointestinal condition in which the digestive tract is chronically inflamed. Symptoms include vomiting, diarrhea and weight loss. Dogs with IBD have significantly lower bacterial diversity as well as microbial communities that are distinct from those of healthy dogs. In 2014, Dr. Suchodolski and his colleagues conducted a study of 22 companion dogs, half of whom suffered from idiopathic IBD (Minamoto et al. 2015). They wanted to know if traditional treatments—steroids and special diets—directly or indirectly created a more robust microbial community.
After treatment, the sick dogs felt a lot better. However, there was no change in their gut microbiota. The researchers concluded, “This study demonstrates intestinal dysbiosis [microbial imbalance] and altered serum metabolite profiles in dogs with IBD. But medical therapy doesn't seem to affect the intestinal dysbiosis.”
It could be that, rather than triggering the condition, microorganisms are compromised by it. Researchers also suspect that biological environmental stresses are involved in ways not yet understood. Dr. Suchodolski added, “It may be that we need longer follow-up periods of treatments to see potential improvements. Another reasonable theory is that with the current standard therapies—for instance, immunosuppression—we just control clinical signs, but the underlying etiology of the disease is ongoing.”
When it comes to treating dogs for myriad problems, vets often prescribe antibiotics, and for good reason: antibiotics save lives. But the war on infection sometimes puts good bacteria in the line of fire, too. When assaulted by repeated antibiotic use, some classes of gut bacteria struggle to recover. If the affected bacteria play a pivotal role in autoimmune health, overuse of antibiotics may coincide with a decrease in healthy autoimmune responses.
Antibiotics are not the only culprits. Scientists suspect that in human births, Cesarean deliveries may contribute to an increase in autoimmune weaknesses as well. In a vaginal birth, the fetus departs the womb without a single microbe but acquires them by passing through the mother’s birth canal. By the time the newborn takes his first breath, he is covered with colonies of bacteria that kick-start his immune system, establish a healthy digestive tract, help shape his growing brain and even protect him from psychiatric disorders. C-section babies start life without the microbes they would have picked up from vaginal delivery, suggesting that the colonization of the newborn might be delayed (Jakobsson et al. 2014).
Medical disorders connected to non-vaginal delivery and the slow introduction of protective bacteria have not been studied in the dog. Considering that a number of breeds with exceptionally flat, wide skulls—such as the Boston Terrier, French Bulldog and Bulldog—must have their pups delivered via C-section, it’s an area that deserves further study.
Or is diet the problem? Commercially manufactured dog chow was introduced in the U.S. in the mid-1920s. By the 1950s, processed dog food like Friskies, Sergeant’s and Purina were widely available through local grocery stores. Today in the U.S., we spend more than $10 billion a year on commercial pet food. The question arises: has the increase in autoimmune diseases paralleled the rise in popularity of processed dog food?
Because veterinary practices typically don’t collect this type of empirical data, the answer is, at best, a guess. But many dog owners think so, and have eliminated or cut back on processed foods in favor of raw meat and vegetables. However, as of now, there is no definitive evidence to show that fresh foods modulate the gut microbiota.
Sophisticated DNA sequencing technology has opened up the invisible world to scientific scrutiny. But determining its impact on the host species is difficult and time-consuming. Researchers need to locate and identify a microbe’s fingerprint, then remove a sample and grow it in a culture, a process especially difficult with shyer microbes that are destroyed by oxygen or stomach acid.
To figure out why we get sick and the role microbes play in illness, researchers must first determine how these trillions of organisms interact with each other. And the fact that scientists can prove a problem exists doesn’t mean they know how to fix it.
Developing therapeutic dog foods that target specific vulnerabilities may help, but will take time to develop. Although the probiotic movement may oversell their benefits, probiotics (friendly bacteria like those that live in the gut) are effective in some cases. And prebiotics, foods that encourage growth of good bacteria already present, may help as well.
The University of Pennsylvania School of Veterinary Medicine (Penn Vet) is recruiting dogs with acute symptoms of diarrhea and/or vomiting for a new clinical trail that will evaluate the role of the intestinal microbiome—the community of “good” bacteria that live in the gut—on chronic gastrointestinal diseases. Therapy will include simple diet change, treatment with antibiotics or combination therapy with steroids for more complicated cases.
Penn Vet researchers anticipate that their study may reveal how gut microbiota influence and respond to treatment, which in turn could lay the groundwork for future projects using treatments such as prebiotics, probiotics or fecal transplants (transferring “good” microorganisms from a donor’s healthy stool to the patient’s gastrointestinal tract). According to Research Assistant Professor Dr. Daniel Beiting, “Whereas past studies have used a single method to sequence bacterial DNA, the Penn Vet study will use a more sophisticated approach called metagenomics, generating a much more comprehensive catalog of bacteria in the stool and providing insight into what they might be doing.”
Penn Vet is currently looking for dogs with chronic gastrointestinal problems. People interested in enrolling their dog in the study—Evaluating the Role of the Microbiome in the Resolution of Canine Chronic Enteropathy—should email Penn Vet’s Veterinary Clinical Investigations Center at email@example.com, or call (215) 573-0302.
Future possibilities are exciting. In the meantime, kiss your dog. It’s good for you in more ways than one.
News: Guest Posts
September 29 2014
In honor of national guide dog month, I'm reprinting excerpts of an interview I did several years ago with seven experienced blind people who've used guide dogs most of their lives. Here they compare problem solving strategies between 36 dogs representing six breeds. Compared to my usual posts, it's a lengthy conversation, but if you've lived with a Lab, Golden, German Shepherd, Aussie, Border Collie, Flat Coat, Poodle or hybrid of these breeds, you'll be fascinated by the comments.
“Because we can’t see, we don’t know the particulars of what we’re commanding our dogs to do. The dog has to stand up to us, to get it through to us that something is there that we don’t know about, then find a way to get us out of a dangerous situation. A dog that isn’t comfortable holding his ground isn’t suited to the job.”
Some blind handlers argue that there are marked differences in each breed’s approach to guide work, while others think that the traits that make good guides neutralize the larger behaviors that characterize each breed.
One blind handler who has worked with a German Shepherd for 10 years, a Lab for seven, two different Golden Retrievers for 15 years, and now has two years’ experience under his belt working with a Golden-Lab cross says that there are some physical characteristics that are different among breeds, such as the gait and how the dog feels through the harness. “Even so, the dog’s unique personality, combined with the person’s — how they work together and what they expect of each other — that’s where the differences are.”
“It’s a 50-50 relationship,” says a handler who’s worked with one Lab, two mixed-breed Labs and two Goldens, and now is partnered with a Lab-Poodle cross. “Neither one of us is in total control at any given time. Both of our lives depend on what the other one does. Neither of us may be able to make a safe street crossing alone, but together we do it gracefully."
“How my dogs dealt with obstacles isn’t, in my opinion, a function of breed-specific differences,” says a seasoned 25-year guide dog user who has partnered with an Airedale, a Border Collie mix, an Australian Shepherd and, briefly, a Siberian Husky. “My Airedale, as I recall him, was quick to generalize about the concept "obstacle” but wasn’t particularly good at scoping out his environment and making decisions in advance.” The Aussie and the Border Collie mix seemed to generalize quickly.
“The Border Collie mix had very high head carriage and was by far the very best dog I've worked when it came to overhead hazards,” he said. “The Aussie has been harder to teach naturally occurring overheads like tree limbs, but whether that's a breed thing or a result of their tendency to work with their heads a little low, I'm not sure.”
Another woman who has worked with two Shepherd guides and one Lab-Golden cross said, “In my opinion, you might say that the retrievers’ style provides more information about the specifics ofthe environment, but the Shepherds’ style makes for more efficient travel. My Shepherds, in comparison to my retriever, both typically looked farther ahead as they guided. They corrected for upcoming obstacles from a distance and our travel path was typically a smooth line. Sudden turns or stops happened only in response to an obstacle that unexpectedly crossed our intended path. My retriever cross clearly does not take the same approach. In general, this dog will stop and show me the obstacle, and he will almost always seek prompting from me on which way to go next.”
Another typical difference between dogs, explains a blind handler is their approach to routes.“Personally I find that my retrievers enjoyed familiar routes. In comparison, my Shepherd gets bored with routine, so you have to get creative with routes and mix things up,” she says.
She adds that retrievers are looking to please the handler, as if asking, “Did I do what you wanted, am I making you happy?” whereas her shepherds have been motivated by doing the job and solving the problems. “With Shepherds, it’s not so much about what pleases me as it is about pleasing themselves,” she says.
A guide dog handler who has worked with three Labs, a Lab mix, a Golden Retriever and a German Shepherd explained, “If I were to generalize,” she says, “I’d say my Labs often worked up to an obstacle before deciding what to do about it, while my shepherd would decide in advance what to do, perhaps starting the turn more gradually as we approached the barrier. My Golden would stop to show me before trying to work it out.”
Eight guide dogs and 34 years later, a handler contemplated her experiences with four Labs, two Goldens, one Shepherd, and one Flat-coat Retriever. “My Flat-coat solved problems by coming to a full stop. Sometimes he would just stand there and I could feel his head moving. People said that he looked like he was weighing all the possibilities. Then he would make his decision. And in nine years of partnership he never made a mistake.”
One woman got her first German Shepherd in 1996 after working with three Labs. She says she had to learn the body language that was unique to the Shepherd. “At first I thought when my Shepherd would insist on going a certain way and I wanted to go another that she was being stubborn or willful. I soon discovered that if I acknowledged her for what she was showing me, and then asked her to go the direction I wanted to go, she was totally fine with that. My second Shepherd is the same way.”
Regardless of genealogy, each dog takes a unique approach to problem solving. “I noticed that the Aussie I’m working with now had a very strong preference for traveling on one or another side of a street when we walked home from work,” explained his handler. “Eventually, I figured out the preference stemmed from whether it was or had recently been raining. One side of the street was commercial, the other had lots of trees with branches that hung low when wet.”
“My Goldens were much more attuned to my reactions to things. If I did hit a branch, I needed only to flinch and they both acted as if they had been corrected. I would describe my Labrador as being solid, but she had the attitude that things would move for her or she would move them. She was careful, generally, but also had no compunction about moving me through some tight gaps. It wasn’t always pretty, but she would get you where you needed to go safely and with enthusiasm.”
Person and dog work as a team, each contributing to a relationship built on trust that begins during class, then deepens and broadens over time. Says a guide dog user with 35 years of experience, “I think developing trust is incumbent on the person. That’s who sets the tone of the partnership so that the dog learns to be, in essence, not just a guide, but responsible for the person’s safety.”
A blind woman who has traveled with guides since 1968 said, “My assumption is that my dog is acting to keep us safe until he proves to be distracted or is putting his agenda ahead of mine. Sure, if that sudden plunge proves to be because my Lab dove for a French fry, the appropriate correction needs to be made. Extra work to minimize that behavior may be called for, but ‘follow your dog’ has to be the first response if we are going to learn to trust and read each other. My safety depends on my ability to read their reactions and go with it and figure out the ‘whys’ later.”
“Working a guide dog is like dancing,” she explains. “And being responsive to my partner’s moves is how it works best for me. I've had had two very large Labs both with a lot of initiative. They seldom asked for my input, made quick swift movements and expected I would be able to keep up and go with them. They were more likely to try to interpose their bodies between me and muscle me out of the way or into safety. My Golden, and my small Lab were likely to be cautious and refuse to leave the curb until they determined that a car they watched was not going to move toward us.”
One man described all his dogs as having been keen observers.“They’ve all had similar complex personalities,” he says. “They enjoyed their work and have been more than willing to guide and do things such as squeeze into small spaces and stay for hours, only because I have asked them to.”
A thirty year guide dog veteran summed it up. "I've owned plenty of dogs as pets, but my relationship with the half dozen guide dogs I've worked with was different: All of my guide dogs seemed to own me rather than the other way around.”
Dog's Life: Work of Dogs
From puppy to partner, guide dogs are a special breed
July 18 2014
Each year, guide dog schools—independent nonprofit organizations that provide guide dogs for blind and visually impaired individuals—breed close to 3,000 dogs. When so many intelligent, loving shelter dogs are in need of homes, why don’t guide dog schools rescue dogs like some of the other service-dog programs? The answer lies in the nature of the work guide dogs are required to do. Dog jobs, like people jobs, are task-specific and require specific temperaments, some of which can be selected for through breeding.
The term “service animal” was first used in the 1990 Americans with Disabilities Act to describe an animal individually trained to provide assistance to a person with a disability. While at that time, guide dogs for the blind were the most familiar type of service animal, over the years, the variety of tasks service dogs carry out has increased to include dogs who perform some of the functions that an individual with a disability cannot perform for him- or herself, such as alerting people with hearing impairments, pulling wheelchairs, or carrying and picking up things for people with mobility issues.
Watching blind travelers confidently make their way through busy city traffic, you might think that the guide dog is doing the same thing—performing a task that the blind person cannot perform for him- or herself. In other words, it may appear that the dog is leading the blind person, but that’s not the case. Both of their lives depend on what the other one does, and neither is in total control at any given time. Neither dog nor person can cross the street alone without risk, but together, they do it efficiently and safely.
Terry Barrett, director of training operations at Guide Dogs for the Blind (GDB) in San Rafael, Calif., says, “In our earliest days, the 1940s, most of our dogs came from animal shelters. It soon became evident that we were looking for something very specific: Dogs who not only had excellent health, intelligence and temperament, but also exhibited a willingness to work and thrived on praise.” GDB’s breeding program was started in an effort to ensure a consistent supply of dogs with those specific traits.
By the late 1970s, new socialization methods (raising puppies in home environments) were proving so successful that shelter dogs, most of whom came from disadvantaged or unknown backgrounds, became less likely candidates for the work. As guide dog work intensified and breeding programs were beefed up, opportunities for shelter dogs all but disappeared.
Labrador Retrievers, who constitute about 60 percent of these working dogs, have proven to be the most successful guide worldwide, mainly because there is enough variation within the breed to meet blind students’ myriad needs. “The vast majority of our dogs are bred from our own specially selected stock, but a percentage are donated from other schools, through international programs and other means,” Barrett notes.
Regardless of lineage, guide dogs have distinct counter-intuitive characteristics in common. Because they are, to great extent, bred for a specific temperament, they are more like one another than they are like others of their particular breed. If they were children, their report cards would read: “Follows instruction, participates in class, very creative, assumes responsibility when necessary, shows leadership and works well in a group.”
Breeders aren’t selecting for these traits as much as they are selecting against others. They want a German Shepherd who is tractable, a bird dog who is not prey-driven, a herding dog who won’t nip people to negotiate busy pedestrian traffic. Unlike traditional breeders who select for niche traits such as pointing, herding or wire-haired coats, schools select for temperament characteristics that are broadly adaptable.
For decades, guide dog schools have conducted and recorded detailed observations on many thousands of dogs. This volume of information and the length of time it’s been collected have allowed schools to reliably classify and quantify temperament traits. Their ultimate goal is to find measurements that will predict guide dog success and estimate heritability of temperament traits that are important to working guide dogs.
Generally speaking, many dog temperament tests have proven to be ineffective and controversial. In addition, few tests account for the dramatic behavioral differences seen from one breed to another; what’s acceptable in a German Shepherd might be abnormal behavior in a Golden Retriever.
According to an article by Taylor and Mills in the Journal of Veterinary Behavior, Clinical Applications and Research (2006), what’s needed are systematic scientific tests that focus on the five key measurements of the quality of a temperament: purpose, standardization, reliability, validity and practicality. It would take a large number of dogs in a consistent setting to devise such a test, and this is where guide dog schools are getting involved.
For example, Guiding Eyes for the Blind, based in Yorktown Heights, N.Y., is working with trainer Suzanne Clothier on a novel temperament evaluation project that tracks the behavior of hundreds of dogs from puppyhood through maturity, investigating how best to identify, and then select for, a set of traits that reflects flexibility of behavior. As Jane Russenberger, senior director of the canine development center at Guiding Eyes for the Blind, observes, “Because we believe in it and, like other schools, need better temperament measures, Guiding Eyes is providing that opportunity by allocating large amounts of resources to conduct the temperament tests.”
Part of the drive to refine this process comes from the financial and emotional commitment made to each dog by both the school and the eventual handler. Although it varies from school to school based on geographic region, on average, it costs about $50,000 to graduate a person/dog team. This figure includes all costs divided by the number of teams the school graduates each year. (The 11 schools in the U.S. graduate about 1,500 to 2,000 teams annually.) The cost just to prepare a single dog for class is about $23,000.
Direct costs—breeding, feeding, vet care and puppy-raising expenses—consume about 25 percent of the budget. Another 20 percent goes into training dogs for class. About 35 percent goes into student selection, dormitory and class expenses, and follow-up services. Once the training is complete and the team returns home, it can be six months to a year before they are functioning optimally together. To assist in this process, schools continue to work with their graduates in their home locations. Some of the larger, better-funded schools provide follow-up services for the working life of the team, which can be eight years. (Everything is provided free of charge to qualified blind and visually impaired students.)
From Puppy to Partner
Careful control of what happens to a young dog during this critical phase of development is a crucial part of producing sound guide dogs. This is the time during which youngsters learn the canine equivalent of “please and thank you.” It’s also the best time to evaluate their health and identify risk factors that could lead to problems later in life. As Barrett notes, “From the earliest stages of their lives, GDB puppies and their moms are cared for by a team of experts, including full-time veterinarians and technicians supported by consulting specialists and volunteers. As the pups grow, our veterinarians continue to monitor their health and well-being.”
All dogs are born with default positions that they revert to when stressed. The reaction can be anything from anxious whining to more serious issues such as biting. The higher the stress, the more pressure on the trigger. Puppy socialization programs provide an opportunity to identify environmental stressors and modify the reaction, or failing that, release the dog from the program to a companion home.
As a handler explains, “Because we can’t see, we don’t know the particulars of what we’re commanding our dogs to do. The dog has to stand up to us, to get it through to us that something is there that we don’t know about, then find a way to get us out of a dangerous situation. A dog that isn’t comfortable holding his ground isn’t suited to the job.”
Guide dogs have to be able to generalize to new, complicated and sometimes abstract situations. It’s easy to train a dog to take someone to a chair. Training a dog to take a person to a place where no one else is sitting, whether it’s a college classroom or restaurant, is a more abstract concept.
Training cycles vary slightly, but generally, puppy raisers return 15-month-old dogs to the school, where they begin 18 to 20 weeks of formal training in the technical aspects of guide work. Using affection and positive reinforcement, the instructor trains the dog to respond to about 35 different commands such as forward, right, left, and find the door.
Weeks one through nine include obedience training, directional turns, negotiating obstacles, light city work, and street crossings. During week 10, dogs are introduced to traffic training. This is the point at which instructors determine whether or not the dog has the confidence and initiative to make the independent decisions needed to override many of the commands he’s learned in the previous nine weeks of training.
To traffic-train a dog, instructors capitalize on what comes naturally: Dogs will move away from an oncoming vehicle. By instinct, the dog will attempt to escape by running around, backing away from or bolting in front of the car. The trick is to control the dog’s movement with reinforcement, encouraging him to back up into the rigid harness handle even though he’s been instructed to go “forward.”
The dog doesn’t know he is signaling (indicating that it’s unsafe to go forward) but he “gets it” soon enough. The light bulb moment—when the dog realizes he is responsible for the person at the other end of the handle—is a deal-breaker for some dogs. They understand the dynamic of the partnership, but they don’t want to do it. It’s a moment puppy raisers anxiously await with mixed feelings. They want their dog to make it through training, but if he fails, they have an opportunity to keep him as a pet. Dogs who don’t want the responsibility go home to be companions. Dogs who meet the challenge move on to learning how to negotiate buildings, busy city traffic, larger street crossings, longer routes, escalators and elevator work.
After the dog is trained, the instructors teach students how to work with the dog during a four-week in-residence class. Person and dog work as a team, each contributing to a relationship built on trust that begins during class and deepens and broadens over time. Handlers are given surprising reminders of the trust they must have in their dogs, and those reminders usually show up the first time they override their dog’s decision to disregard a command. Tripping over a garden hose is minor compared to the consequences of stepping off a curb in front of an SUV making an illegal turn, but the lesson is the same.
Guide dog handler Sheila Styron, past president of Guide Dog Users, Inc., the largest organization of dog handlers in the world, explained what it’s like from the other end of the harness handle. “If a handler sits at a desk all day, his or her guide dog needs to be able to lie quietly for hours, and then be able to confidently guide the blind handler on to a noisy, crowded subway. It’s important to consider the wide array of other factors and interactions within the relationship between dog and handler that can contribute to the team’s success, difficulties or failure. The dance is extremely complex, and the magic extraordinary when all the elements fall into place.”
Culture: Science & History
Breeders, judges and historians talk about breed standards—why they work and when they don’t
September 18 2013
In the world of mammals, the domestic dog— Canis lupus familiaris, a subspecies of the gray wolf— reigns as the most morphologically diverse. Consider, for example, the extremes represented by the 155- pound South Russian Ovcharka and the seven-pound Silky Terrier. This incredible variety can be attributed in part to the dog’s basic template, which can be customized by the manipulation of a very small number of genes.
For instance, 95 percent of all five canine fur textures and lengths (the Afghan Hound and Curly-Coated Retriever curiously excepted) is orchestrated by three genes. Further, just six or seven locations in the canine genome account for nearly 80 percent of dogs’ vast size and weight differences. (In humans, these genes number in the hundreds, if not thousands). A single mutation, shared by 14 diminutive breeds, determines that a dog will be small, and another is responsible for the long-bodied, short-legged nature of numerous dwarf breeds.
Clearly, the dog’s random morphology isn’t quite as arbitrary as we thought, and breeds aren’t quite as unique. Furthermore, canine traits come in packages. Flip a switch to make the legs more slender, and the skull will narrow as well. Turn down the volume on pigment and the chance of deafness increases.
Those who bred dogs had long known that traits were related, but there was little understanding of how those relationships worked; nor was there much concern. Dogs were bred for skills useful in a practical world. Once breed exhibition became a fashionable pastime and working dogs were awarded championships based strictly on appearance, however, all this changed.
In 1866, John Henry Walsh (writing under the pseudonym “Stonehenge”), editor of The Field, the most influential hunting and kennel journal in England, was the first to describe a breed’s physical characteristics with phrases that he believed were equivalent to its field ability. A bird dog judged perfect to a well-written breed standard would, by the logic of the day, perform perfectly in the field.
At the time, horsemen and sportsmen were the dog-fancy glitterati (women became active later), and many of the arcane descriptions in breed standards are borrowed from those arenas. For example, the Poodle’s “straight-forward springy trot” describes the dog’s ability to retrieve and carry a bird. The phrase “stand like a cleverly made hunter” references ideal anatomical construction and proportion in the German Shorthaired Pointer.
Today, breed standards serve three purposes: assessment in competition; delineation of unique qualities in different breeds, some very much alike; and maintenance of breed similarity throughout the world.
The question is, what happens to purebred dogs when language, intrinsically fluid and inexact, is used to suspend change in morphology and behavior? In the late 1990s, as a doctoral student in linguistics at Claremont Graduate University, I conducted a study to find out. Part of the research included interviews with experienced American Kennel Club (AKC) breeders, specialty judges and breed historians. What I heard from them provides some insight into specific ways that a standardized lexicon can influence change in pedigreed dogs far beyond what is intended.
Dogs in Translation For some breeds, international politics played a role. At the first Canine Congress in 1886, the Germans were opposed to the Swiss-type Saint Bernard, favoring the bulkier English type. Nothing was resolved until 1887, when the Swiss dog was finally approved as the international type. The United States club, with its strong ties to England, adopted the international standard in words, but in practice, bred to the English type.
During an interview, as three Saints gnawed on bones nearby, an experienced breeder and specialty judge offered his opinion: “This changed the morphology of the American Saint, most noticeably in the head. The Saint Bernard standard was translated, with some errors, from German to English in 1888. For instance, ‘when in action’ should have read ‘when excited or alert.’ The phrase, ‘the horizontal axis of the head’ should have read ‘the long axis of the head.’” More than a century later, the club had still not made corrections, perhaps because, as linguists argue, translation of a lexicon from one language to another can never be exact.
Translations are more like corrections or clarifications. When standards are clarified, they usually get longer and, consequently, more exclusive. A standard that calls for feet to be “round, compact, catlike, standing well upon the toe pads,” is more restrictive than one that says feet must be “close, round and firm.” Revisionists tread cautiously because an imprecisely rephrased standard can have an impact on a breed’s genetic diversity.
Amending a standard for any reason is controversial for those entrenched in a time-honored tradition devoted to blueblood history (albeit a fanciful history, since geneticists tell us that very few breeds are as old as they were once touted). As one Greyhound breeder observed, “The torch handed to us was the perfect coursing dog. Our standard is taken word for word from what Stonehenge wrote in the 1860s. If we added more words to make it more explicit, it may end up being a Greyhound different than the one each one of us has in our head.”
But progress necessitates change. A handful of words differentiate an apple, an orange or a pear, but 13 varieties of apples require a larger lexicon. In his 1576 treatise, Of Englishe Dogges: The Diversities, the Names, the Natures, and the Properties, cynologist John Caius described the generic land Spaniel in 58 words: “The most part of their skins are white and if they be marked with any spots, they are commonly red, and somewhat great therewithal, the hairs not growing in such thickness but that the mixture of them may easily be perceived. Other some of them be reddish and blackish, but of that sort there be but a few.” Today, Caius’s dog has morphed into 13 f lushing Spaniel breeds. The Field Spaniel standard uses 973 words, short in comparison to the English Springer Spaniel standard, a 2,040 word descriptor.
Occasionally, words are added to explain what something is not. As one breed standard committee member noted, “There were lots of questions from judges about the preferred shape of the eye opening. So we said it’s acceptable as long as it’s not this, that or the other thing.” And at a California dog show, pointing to Mastiffs benched only a few feet from his St. Bernards, an exhibitor told me, “Sometimes breed clubs have to lengthen standards to differentiate their breeds from others so similar that, if marked differently, could be shown as Saints.”
When Words Fail Dressed in formal attire appropriate for the straitlaced Madison Avenue cocktail party that precedes every Westminster dog show, AKC VIPs sipped their drinks and talked candidly about breed standards.
A Doberman breeder, specialty and all-breed judge opined, “I’m not sure that the standard hasn’t been what’s wrong with some of the breeds, in that by naming and describing the criteria with which the animal is to be judged, the words lack exactness. When people bred to the standard, the animal changed and became what the words described. Also, some groups wrote the standard and have not been able to breed to that ideal, so now, they change the nuance of the words to fit the breed ideal. Making the dogs fit the words, and not vice-versa, is wrong.”
For instance, a standard that establishes criteria to develop the best muzzle shouldn’t include terms that are subjective or indefinite. Or as one judge said, “If the standard calls for a short muzzle, judges select dogs based on the shortest muzzles in the ring. The breed’s muzzle gets shorter and shorter. So you have to ask, ‘Shorter than what?’”
Another said, “Our standard calls for the ear, when pulled forward, to reach the eye. You see so many dogs in the ring now with longer ears. We always say, well, which eye is it supposed to reach, and is it pulled under the muzzle or over it? I have never seen a Golden Retriever with ears too short.”
Some breeders get so fixated on one attribute of the traditional standard that they are willing to sacrifice something more important. “For example, they may create a broad head but are willing to accept shorter legs and a longer back in order to do so,” another judge observed.
Breed standards, like all nomenclature, are subject to the rules of language. Like the dog it describes, vocabulary is deceptively capricious and unexpectedly fluid. A good example is size. Big breeds are getting bigger. As I was told by a breed historian in reference to St. Bernards, “What was bred to be powerful and strong in 1900 would not be considered powerful and strong today. Like an automobile in 1915, it was powerful then but not compared to now.” If a standard describes a breed as strong and powerful, the ideal dog gets bigger.
Rather than hack away at standards, some breed clubs hold seminars for judges in which contemporary nuances of an indefinite vocabulary are refined. Others reluctantly reword phrases to accommodate inexperienced newcomers (currently, the average length of interest and activity in the dog fancy is five years or less). A Golden Retriever breeder told me, “People who wrote the original standard were horse people, and this is where the phrase, ‘deep through the heart’ came from. It had two meanings, deep through the chest and courageous. The original meaning and nuance of the old words is often lost on today’s breeders, or is interpreted to mean something else.” After years of debate, the phrase was reluctantly changed to “deep through the chest.” Some clubs don’t revise words, but instead, reinterpret their meanings. Take English Bulldogs, for example. As an owner of one of these stocky dogs remarked, “The interpretation of words has changed. The Victorian [Bull]dog was a transition dog, less bulky, less massive, taller, leaner, and is now thicker and more compact.” Another handler observed that “one of the issues in the standard is weight. It calls for 45 to 50 pounds. But it has no height restriction, so a higher-station dog might be thinner.” The 1910 dog was a much taller and leaner dog compared to today’s stout fireplug variety, but both are considered to have been bred correctly to the standard.
A German Shepherd breeder and specialty judge who chairs the club’s standard committee told me that “you can have the same words in several standards, but they don’t mean the same thing. We use the word ‘almondshaped’ in our standard. But if you look at other breed standards, both the Collie and American Cocker call for almond-shaped eyes. The Collie has a small triangular eye and the Cocker’s is a goggle-eye [the eye protrudes from the skull].”
Judges Play a Role A specialty judge is an experienced breeder and expert on a particular breed. An all-breed judge is a generalist qualified to judge several breeds. The specialty judge brings meaning to the words in the standard, and the allbreed judge makes sure the words mean what they say.
A specialty judge who also works as an all-breed judge explained that the interpretation of complex descriptions, such as the angle of the hock, is more difficult for a generalist all-breed judge to measure. “Because it’s easier to see a proper bite than a proper angulation, the bite may be given more significance than something more important, such as angulation of the hindquarters.” On the other hand, the all-breed judge tests the words. “If the breed club thinks the all-breed judge is misinterpreting the standard, then they need to rewrite it. The judge shouldn’t choose the dog that he thinks they mean.”
War of Words The AKC considers itself a club of clubs. Owners intent on breed registration must first demonstrate that a majority of breeders are interested in establishing a national breed club. Who gets to be in that club is at the heart of a mounting number of controversies.
In 1994, the AKC Labrador Retriever standard was revised to exclude dogs less than 22 inches at the withers (or 21 inches for bitches). Some breeders whose dogs no longer met the standard were part of an $11 million class-action suit against the AKC Labrador Retriever Parent Club (the national organization designated by AKC to represent the breed), claiming that height restrictions excluding shorter dogs no longer described the Labrador Retriever: if you make a bigger dog, you make a different dog. A litigant told me, “It’s perfectly reasonable to change a breed, but the dog should have a different name.” They tried and failed to trademark the name Labrador Retriever; the judge sided with the AKC parent club. The Border Collie war began in 1988, when the American Border Collie Association and others heard rumblings that some wanted to register the breed for conformation showing, which requires a breed standard. This idea didn’t go over well with herding trial enthusiasts; a Border Collie is what it does, not what it looks like. Any dog can enter an open sheepdog trial. There are no age, size, color, shape or breed restrictions, and registration is not required. Unlike registered purebreds, whose lineage must be proven in ancient studbooks, many Border Collie champions are registered on merit (ROM). In theory, a Pomeranian who could prove its worth at a sheepdog trial could, by performance, be called a Border Collie.
In the minds of many, AKC conformation specifications threatened 200 years of breeding for performance, not looks. Led by Donald McCaig, who retold the tale in his book The Dog Wars (2007, Outrun Press), the group prepared for battle: “Hands off the Border Collie! We own Border Collies. Our dogs are companion dogs, obedience dogs and livestock-herding dogs. For hundreds of years, Border Collies have been bred to strict performance standards and today they’re the soundest, most trainable dogs in the world. The AKC wants to push them out of the Miscellaneous Class and into the show ring. They seek a conformation standard [appearance standard] for the breed. We, the officers of every single legitimate national, regional and state Border Collie association, reject conformation breeding. Too often, the show ring fattens the puppy mills and creates unsound dogs. We will not permit the AKC to ruin our dogs.”
They filed to legally trademark the name but, like the Lab litigants, lost in court. In 1997, the first Border Collie was shown in conformation at Westminster. I was there that year and interviewed a handler/owner who had been instrumental in getting the breed registered and in writing the standard. I asked her how she did her research. “This dog is shown in Australia, the British Isles and New Zealand. So I read their standards and asked them what they would do differently if they could. I tried to emphasize movement and gait. The standard shouldn’t describe a still dog. The Border Collie is almost a vision of movement even when it is standing still … always poised on the brink of action. The head drops for a reason. It is common knowledge among Border Collie people. That’s why I didn’t include a description of the head in the standard. I thought everybody would know that.”
In the benching area, surrounded by panting dogs crowded into crates and standing patiently while being primped on grooming tables, the woman sat in a folding chair, visibly distraught. Tearyeyed, she continued: “Right before you got here, a prominent breeder came by and said he will breed a dog with the head held higher. The head has to do with movement in the field, in making eye contact with the sheep, the pattern of behavior that has evolved from two centuries of work. Now I regret having fought so hard for this. The standard should not threaten the dog as a working animal, but I believe it now will.” About the same time the Border Collie war was raging, AKC enthusiasts saw an opportunity to register the Jack Russell Terrier (JRT), an irascible, independent dog with an intense work ethic, extremely diverse genome and phenotype as dissimilar as that of the Border Collie. Many Jack Russell Terrier breeders vehemently opposed the action, claiming that the breed’s physical and working characteristics would be jeopardized by this move. Nevertheless, the splinter group formed the requisite national breed club, named itself the Jack Russell Terrier Breeders Association (JRTBA) and gained AKC recognition in 2001.
A lawsuit ensued. After an expensive court battle, the name Jack Russell Terrier was awarded to the working phenotype and the AKC changed the conformation dog’s name to Parson Russell Terrier. The AKC parent club is now the Parson Russell Terrier Association of America.
Writer Alston Chase, who includes the story of the breakup of the breed in his book We Give Our Hearts to Dogs to Tear (2008, Transaction Publishers), told me, “The Jack Russell Terrier is a feisty, very aggressive, very tough dog. But middle-class urbanites don’t really want that kind of dog. They want a dog that will be a good pet.” Chase, who lives in rural Montana, has bred the working terrier since the 1970s.
The public took notice of the rather obscure breed when it became a media darling in the 1980s. Chase said, “The overbreeding followed the popularity driven by the media, not by the dog itself.” Aggressive and difficult in a pet environment, the breed was misrepresented as a mischievous lap dog on shows like the NBC sitcom Frasier. Surprised and disappointed by their dogs’ ornery personalities and exercise requirements, urban pet owners abandoned JRTs at shelters in record numbers.
According to Chase, one of only a handful of people in the U.S. continuing to breed the old-fashioned dog, “We’re doing what we can to prevent extinction of the original breed, but people aren’t in love with the value of diversity in the dog. They want dogs that look alike.”
Geneticist Jasper Rine, in a letter to the AKC supporting the Border Collie anti-conformation campaign (included in the appendix of McCaig’s 2007 book), predicted what was to come. “It may be nearly impossible to breed for a particular behavior based on heterozygous advantage and still achieve a homogenous conformation.” Breeding dogs for fixed conformation means breeding for homozygosis (the formation of genetically identical gametes) of the genes that contribute to appearance. In doing so, genetic linkage (the tendency of genes located in proximity to each other on a chromosome to be inherited together during meiosis, or cell division) may result in genes near those controlling conformation becoming homozygous as well. Unfortunately, chance determines which genes are swept up. By breeding for conformation, breeders may be breeding away from desirable behavior, even putting alleles (forms of a gene) at risk for extinction.
So, what has happened to the Labrador Retriever, Border Collie and Jack Russell Terrier over the last 15 years?
The shorter-legged, more compact field-bred Lab continues to be shown in Canada, the UK and other countries that don’t disqualify individuals based on size. In the U.S., conformation and companion Labs are getting increasingly larger. Will diseases linked to large size compromise the American line? Time will tell.
As a consequence of the acrimonious Border Collie war, few working dog breeders had a desire to become specialty judges, so the fate of the conformation dog was left in the hands of generalist judges who lacked sheepdogtrial experience. As predicted, the standard created a split type: working dogs continue to be a rag-tag group, dissimilar in shape, size and color, but the same in their relentless determination to move sheep from one place to another. In contrast, AKC dogs look very similar, but their ability to herd sheep is open to question. Are both types called Border Collies? Formally, yes, but the AKC dog is widely, popularly and even affectionately known as the “Barbie Collie” by some: pretty as a picture, but, according to the member-owned American Border Collie Association and others, as blandly attractive and vacuous as the doll from which the name derives.
The working Border Collie is safe for now, but the old-fashioned Jack Russell Terrier can hardly be found. Like the Old English Bulldog who faded away with the passage of the 1835 Cruelty to Animals Act and the Wolfhound who died out with the demise of the wolf in the British Isles, the pre-AKC JRT will likely disappear as well. Eventually, sentimental breeders may attempt to recreate the breed when they realize what they’ve lost, and they may perhaps have some success in replicating the way the dog appeared. But the breed’s signature obstreperous temperament is something people will only read about in books.
* * * * *
It would seem, then, that words are indeed powerful. To say that the lexicon used to describe a purebred dog, or even name one, will not affect the way we engineer the animal contradicts the language-relativity hypothesis, which holds that the vernacular we use to frame our perceptions influences the way we regard, understand, interpret and reinvent them. As a tool, language plays an important role by which innovation—in this case, of a sentient human-made domestic animal—is further developed. Or, as the AKC says, refined.
To paraphrase Shakespeare, would a rose by any other name smell as sweet? If you’re talking about dog breeds, that’s not a rhetorical question. The answer is no.
News: Guest Posts
One dog at a time
June 22 2013
For Havana's dogs, it's not the best of times, but it's not the worst either. Some improvement is due to the efforts of the non-governmental Cuban Association for the Protection of Animals and Plants (ANIPLANT), an organization focused on improving the lives of dogs and other animals in Havana. Founded in 1988 by Cuban entertainer Maria Alveres Riso, and Cuba's first prima ballerina, Alisia Alonso, ANIPLANT eliminates animal suffering through massive spay and neuter campaigns, public education, animal health promotion, and hands-on intervention in cases of animal suffering. The founder's daughter, Nora Garcia, who is now president of the organization, talked with me during a visit to the re-purposed house located within walking distance of the heart of Old Havana. The neighborhood, like many in Havana is a contradiction—tidy and clean in spite of decades of neglect.
Prior to my November 2012 arrival in Cuba, without too much difficulty I'd arranged to meet Nora. When my friend, Florence, and I arrived, we received a warm wet-nose welcome from 11 rambunctious happy dogs. Like most, they weigh between 15 and 30 pounds. All are rescues, but unlike their street counterparts, they are on the portly side, mange and parasite free, confident and playful.
The 2000 square foot building, originally a 1920s home, was officially turned over to ANIPLANT in 2007, in very bad shape. Donors, usually dog-loving tourists, helped to rebuild the interior, donating office equipment, lights, chairs, time and money. But money goes only so far in Cuba, because there is very little to buy. The reception area was welcoming, squeaky clean, and decorated with photos of dogs before they were rescued accompanied by after photos as well. Staffed by a few dedicated volunteers, the clinic is open two days a week. Veterinarians volunteer their time as well, but are sometimes paid a small fee when possible.
In urban Havana, people who own dogs often give them free range. I saw a few dogs wearing hand-made ID tags, indicating that someone takes care of them. However, taxes and tags are expensive, so most people own dogs unofficially. I estimate that less than 15% of the city's free-ranging dogs are true strays. The others are sustained by some type of care, from scraps and water, to real meals, to indoor privileges.
ANIPLANT rescues dogs in jeopardy. But they also respond to phone calls from concerned citizens. Many are tourists, who often make donations for the rescue and care of specific dogs, usually ones that frequent the hotels. Some tourists want to take the dogs home, but this is especially tough in a country like Cuba. Most rescued dogs suffer from mange, anemia, distemper, gastroenteritis issues, tape worm, ear mites and renal infections. Due to lack of space, money, homes and people who can't afford to care for a pet, dogs are medically rehabilitated, sterilized, then placed back on the street where they receive minimal care from neighborhood dog lovers. Special case dogs stay at the clinic as permanent residents.
We took a tour of the ANIPLANT facility. The kennels are more like rooms and corridors that can be closed off when necessary with ancient wrought iron gates. Except for the upstairs office, the facility seems to be open for free-run. In Havana homes, interior rooms open to a patio courtyard and this one is no different. I'd be stretching it to say this is an outdoor exercise area. It's more like a lounging area where dogs siesta and soak up sunshine. For easy clean up, they are trained to pee and poop in potted plants. Building materials are neatly stacked outside, waiting for money and an opportunity to be turned into something more useful than just shade. But in Havana, shade is good, too.
In 2007 it was estimated that 20 thousand dogs roamed Havana streets. You can help. To find out more about ANIPLANT and see more photos of my visit, go to http://doctorbarkman.blogspot.com/2013/06/street-dogs-in-havana-cuba.html
Culture: Science & History
Village dogs’ genetic code may hold clues to canine evolution and health
May 20 2013
Like classic twin studies that investigate the interplay of nature and nurture, comparing the genome of village dogs to modern dogs may help disentangle the long-term evolutionary effects of genetic and environmental influences.
Mastiff to Min-Pin, Corgi to street cur: all dogs share the same set of roughly 20,000 genes. What makes one dog different from another—or, in the case of purebreds, almost the same— is how the genes are expressed and restricted from being expressed, and how they communicate with one another. Therefore, it may be safe to say that each of the world’s 800 to 900 million dogs is a distinct combination of different versions of the same genes. Or maybe not. At least, that’s what some scientists suspect, and they think they’ll find answers in the DNA of the ubiquitous, free-ranging canine outcasts that populate developing countries throughout the world.
While village dogs were being socially shunned, modern dogs—a subpopulation that likely split off from village dogs thousands of years ago—were serving society. So tightly woven into the fabric of our lives that we rarely think of them as human-engineered, dogs have been refined for increasingly specialized tasks such as hunting, transportation, protection, warfare, ornament and companionship. As a result of rigorous artificial selection over a long period of time, many of their ancestral gene variants are suppressed. Some have disappeared altogether, creating a fragile homozygous genome that has little diversity.
In contrast, village dogs are barely tolerated by society. Although considered a domestic species, they are the products of thousands of years of natural selection. Consequently, their heterozygous genomes are robust and extremely diverse. In addition, it’s possible that long after modern dogs branched off from the family tree, some village dog populations may have developed new gene variants that protect their immune systems.
Evolutionary biologist Adam Boyko, assistant professor in the Department of Biomedical Sciences at the Cornell University College of Veterinary Medicine, is confident that comparing and contrasting the two branches of the domestic canine family tree will provide answers to some of the mysteries that continue to surround the evolution of the domestic dog: When and where were dogs domesticated? What were the global migration paths of humans and dogs? What genetic changes occurred when wolves became dogs? Which genes are responsible for extreme size, shape and behavior differences? What are the underlying causes of genetic diseases? And how do parasites have an impact on canine well-being?
As a postdoctoral student at Cornell, Boyko worked under the tutelage of Carlos Bustamante, now professor of genetics at the Stanford School of Medicine. Curious about how the underappreciated and even less-studied village dog genome might reframe our current understanding of canine evolution and domestication, Boyko and Bustamante persuaded Ryan and Cori Boyko (Boyko’s brother and sister-in-law, who were then both graduate students in anthropology at the University of California, Davis) to add a few side trips to their otherwise romantic African honeymoon. Their instructions were to catch semi-feral, uncooperative village dogs and draw blood samples, then ship the samples back to the lab for analysis. Information from the preliminary DNA samples indicate that the researchers are on the right track. I asked Dr. Boyko about his research, and if it has future application to invigorating the health of our companion dogs.
Jane Brackman: How will mapping the genome of the village dog help us understand the mechanisms of traits in modern dog breeds?
Adam Boyko: Geneticists have spent a lot of time looking at purebred dogs. When something is selected for, either by natural or artificial selection in a population, geneticists can tell because of the patterns that are left in the genomes of individuals in those populations. In humans, for example, we can clearly see that lactase persistence, the ability to digest milk into adulthood, was selected for in some populations.
When we look for these patterns in purebred dogs, we find that things like ear f loppiness and tail curliness are driving these patterns, or short legs or small/big size. Basically, we find the effects of artificial selection by humans for breed standards. If we did a similar scan for selection in village dogs, perhaps some of those same genes would show patterns of selection, but I think we’d also see a new class of genes showing patterns due to natural selection.
For example, maybe there was a lot of selection in early dogs for genes in certain metabolic pathways because there was such an extreme dietary shift from wolves to dogs. Or maybe new parasites and pathogens caused selection at genes influencing the immune system. Or maybe we’ll see selection around genes that influence behavior and temperament.
Basically, there are all sorts of theories about how dogs became domesticated and what makes a dog a dog. When we look at purebred dogs, the main thing we are able to see is what makes certain dog breeds look and behave one way versus another. Maybe by looking at village dogs, which are much less influenced by the strong and recent artificial selection taking place in breed dogs, we’ll be able to see patterns of selection that occurred earlier in dog history.
JB: Might your findings have application for the future? For example, if you were to come across genes influencing the immune system, would breeders be able to use that information to revitalize the pedigreed-dog immune system?
AB: It is certainly true that my research may find a new MHC-type immunity gene [the major histocompatibility complex mediates the immune system’s white blood cells] that has been lost in many purebred dogs and which could reinvigorate their immune diversity. Or perhaps it will find variants associated with diet, and make us start considering a dog’s genetic makeup when making dietary recommendations. But I’m really not comfortable speculating, since I’m likely to be quite wrong in these predictions.
For example, I would have never guessed that deliberately infecting patients with intestinal parasites [Helminthic therapy] would cure ulcerative colitis, but that seems to be the case, and signatures of selection in the human genome help explain why.
But having said that, I think looking at the genomes of village dogs will be extremely useful. For example, we could get a better picture of the kinds of traits that were selected for in natural dog populations, including disease resistance, which might give us useful insights into diseases we diagnose in our pet dogs.
Conversely, as veterinarians and geneticists find more mutations that cause disease or unique traits in dogs, we can look at the genomes of diverse village dogs to see when and where these mutations arose, and whether they are also found in any other village or purebred dog populations.
It’s a really exciting time to be a canine geneticist, as we have all these new genetic tools at our disposal and many, many purebred and free-ranging populations that have yet to be characterized genetically.
JB: Some populations of village dogs, such as those you’re studying, have been isolated for many thousands of years, evolving under pressures that the stem parents of modern breeds were never exposed to. Is it possible that these dogs have “new” gene variants that don’t exist in the genome of modern breeds?
AB: It’s certainly possible, and it’s something I’m very interested in. For example, my lab is looking at free-ranging dogs in the highlands of Peru to see if they have any genetic adaptations for high altitude. Perhaps more importantly, some village-dog populations might harbor disease-resistant variants for parasites or pathogens that are prevalent in their area, but these variants might not have made it into modern purebred dogs, since those breeds were mostly founded elsewhere.
JB: How urgent is it that we learn more about these ancient dog genomes?
AB: We know how quickly pre-Columbian Native American breeds were lost when Europeans brought dogs with them to the New World, and we see that it will happen like that very soon in other remote parts of the world. So we’re working as fast as we can to get the data before the dogs are gone.
JB: What’s going on in your lab now?
AB: We’re collecting DNA samples and the genetic information we need so we can start piecing together what’s going on in these interesting but largely neglected free-ranging dog populations. We are seeking insights into dog population history to discover patterns of selection around certain genes that can then become the basis of further study. Our work is very hypothesis-driven. We have certain hypotheses about how dogs evolved, and we try to collect the right samples to test these hypotheses.
As geneticists learn more about how genetic variation controls complex traits in purebred dogs, we find it’s quite different than what we see in humans. Why? There are at least two competing hypotheses, and by gathering data from free-ranging dogs, we can start testing them to figure it out. Some of this gets into technical discussion about genetic architecture, recombination, epistasis and pleiotropy and such, so I’ve avoided getting too academic. But I also don’t want to be dismissive of it since those technical, hypothesis-driven aspects of the project are the bread and butter of my lab in terms of student training.
JB: In longitudinal studies such as the Morris Animal Foundation’s Golden Retriever Lifetime Study, researchers gather information from participants’ DNA and then match what they find to traits the test dogs may display over a lifetime. Will you have an opportunity to see how, for example, an immunesystem mutation affects a village dog’s health as it ages?
AB: Our project is a huge undertaking, and there’s a ton of data we’d love to gather on each dog but just simply aren’t able to since, at this point, we’re focused on sampling as many dogs from as many populations as possible to maximize the amount of diversity we can analyze. I really don’t want to overstate what we’re able to do in one visit to check out a dog and draw blood, which is limited to looking for genetic signatures in the genome of these dogs showing signs of selection and/or local adaptation.
But, since we have a fairly good idea of what genes do in modern dogs, at least in a rough sense, if we see a genetic signature in village dogs for positive selection around a gene we know is involved in immune function (for example), that’s a big discovery.
JB: At the risk of oversimplifying, say you’re looking at a region that you know to be linked to a negative trait and you see that the switch is turned off in the village dog DNA and turned on in modern dog DNA—would you feel that you’d found a “smoking gun”?
AB: It’s possible. Then, of course, as you allude, we would want to go back, look at dogs carrying that mutation versus other dogs, and see if there are different health outcomes. Perhaps [dogs with the mutation] are more resistant to intestinal parasites or perhaps they are more prone to autoimmune disease or something. Until we find the mutations, it’s a bit speculative to make predications about what exactly the findings will mean to owners. This is certainly “basic research” in the purest sense.
JB: In people, size is determined by hundreds of genes, each with a small effect. In purebred dogs, body size can be regulated by a single gene. Is this unique to dogs?
AB: It depends. There are other traits in other species controlled by a couple of loci [location of a gene on a chromosome]. I would argue that yes, it’s pretty unique. Whether or not dogs are special in that there is something about their genome that predisposes them to this type of diversity, or perhaps because humans worked so hard at creating them, we don’t know. This debate is still raging in the literature. It is definitely the case that genes have many, many effects. Rather than being a blueprint in which each gene is responsible for just one part of building the whole organism, the genome is more complicated, with each gene taking on different roles at different times or in different tissues.
JB: Do multiple-trait relationships also show up in village dogs?
AB: I think this would also occur in village dogs if the mutations were in those populations. The difference is that selective breeding has actively promoted these large-effect, diversifying mutations in dog breeds, making them relatively more common. Natural selection usually selects against such large-effect mutations in natural populations. You won’t see a short-legged wolf because it couldn’t hunt.
In fact, most of these large-effect mutations probably first arose in village dogs. The difference is that these mutations aren’t usually beneficial to village dogs, but the ones that aren’t too detrimental might persist at low frequency long enough for humans to start trying to promote breeding of that trait. Take achondrodysplasia [a type of dwarfism]. It almost certainly arose in village dogs, but to a free-ranging dog, super-short legs and all that comes with them probably aren’t much of a selective advantage. But once folks started looking for dogs to turn their spits, they found these super-short dogs to be useful, and eventually that genetic variant made its way into a whole host of modern breeds.
For the specific achondrodysplasia mutation, I don’t know if that is the exact story, but I do think this is likely to be the case for many large-effect mutations. Depending on how early in dog evolutionary history the mutation arose, it could be found in most regional village dog populations, or it could be restricted to certain populations that are close to where it first arose. Lots of research still left to be done!
JB: As a lifelong dog lover, you must find it difficult to see the deplorable conditions in which some of these dogs live.
AB: There’s so much disease in these high-density populations. As these communities become more urbanized, dogs are living like rats and pigeons. Getting DNA on these populations is not enough of a reason to allow the animals to exist like this. Life on an urban street is rough existence.
JB: If you adopt a village-dog puppy and raise it in a typical Western environment, what kind of dog will you have?
AB: Adopting the dogs is not part of our project, but we know people who have done this. They can be great dogs. They don’t have some of the aggression issues you might see in some of our dogs, because they are culled for aggression, or for eating a chicken. There are some things that aren’t tolerated. So you might say that people in the villages impose a form of selection. The dogs are smart and resourceful. They seem to adapt.
News: Guest Posts
February 3 2013
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
January 28 2013
“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.
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