Dog's Life: Lifestyle
It matters more than brightness
One of the most persistent errors about dogs is the claim that they are colorblind. It has been known for decades that dogs can see colors, but research into the details of how they use their color vision can still reveal new information. In a recent study called “Colour cues proved to be more informative for dogs than brightness”, researchers asked the simple question, “Do dogs attend to color or brightness when learning the cues that indicate the presence of food?
In the experiment, researchers trained dogs to make a choice between boxes concealing food. The boxes were each marked with a colored paper, and the dog had to learn which one indicated a piece of meat was inside. Dogs were trained to discriminate between either light yellow and dark blue or between dark yellow and light blue. Then the dogs were tested to see if the cue they used to make correct choices was the color of the paper or the brightness of the paper.
For example, a dog who had learned to choose the box marked by a dark yellow piece of paper was tested with a choice between a box marked by light yellow or a box marked by dark blue. The experimenters were asking whether the dog had learned that “dark” indicates the presence of meat or whether “yellow” does. They found that dogs were making choices based on color, not brightness, in the majority of cases. It was a small sample size of only 8 dogs, but it suggests that dogs not only see color, which has long been known, but that they pay attention to it more than to the depth of color.
It is not surprising that if dogs have the ability to see color that they would use that color functionally in various situations. Asking whether dogs distinguish dark from light when the opportunity to distinguish by color is also present may be an important preliminary step in understanding what dogs attend to. However, I would be even more interested to know whether dogs favor color over shape, color over size or even color over various sounds to make their choices, as all of these seem more biologically relevant to dogs seeking food than brightness does.
Dog's Life: Humane
We humans are terrific at measuring and recordkeeping— we even know the length of Noah’s ark, in cubits (300) no less. Technology abets this trait, as computers dutifully crunch our numbers, ad, well, infinitum. As a species, however, we are not so good at appraising information to extract its meaning. Confronted with new data, we tend to overemphasize and generalize, often less than critically.
On that cautionary note, what are we dog people to make of a new University of California, Davis, study that examines relationships between early, late or no spay/neuter and several health conditions in Golden Retrievers? How do we apply its conclusions to the animals in our care?
The Davis docs found increased risk of several cancers, hip dysplasia and cranial cruciate ligament tears among sterilized Goldens; the incidence varied according to the sex and age-at-neuter of their subjects. As such, their findings add to a growing library of veterinary literature on the spay/neuter subject. However, the authors are careful to limit their conclusions, as should we.
First, the findings are breed-specific. Goldens, a highly inbred line, were chosen in part because of their susceptibility to cancers and joint issues. The gene pool was further limited by a study sample of dogs (759, to be precise) seen at the UC Davis clinic, in northern California.
Second, we need to remind ourselves that risk is not destiny, and that correlation is not causation. The study notes that the risk of one type of canine cancer quadrupled in late-neutered females, but also reveals that its incidence grew from 1.6 to 7.4 percent— meaning that about 93 percent of the subjects did not contract the disease.
The authors also indicate that they did not specifically consider obesity, another known factor in dysplasia and cancers. Neutered dogs do tend to be heavier, but we can manage that risk by controlling food intake and quality. We also need to recognize that other studies have noted countervailing positive health effects, as spay/neuter reduces or eliminates rates of other common diseases, such as mammary cancers and uterine infections.
Third, context is crucial. These data feed into the universe of things that are harmful to canines. We know, for example, that nationwide, some 50 percent of the animals in shelters don’t survive the experience. To the extent that intact canines contribute litters to the shelter population, that risk dwarfs exposure to accidents or disease. Shelter “save” rates are improving in many places, but we remain far from a no-kill equilibrium. Job One for canine partisans (including the veterinary community) remains the imperative to reduce that carnage.
After sheltering, risk-of-death varies widely by age and breed. A comprehensive University of Georgia study of vet-reported deaths (“Mortality in North American Dogs from 1984 to 2004,” published in 2011) identifies infections, trauma and birth defects as primary culprits in young dogs, with tumor-related diseases at various breed-specific rates, distantly followed by trauma and infections, which dominate the tally for the late-in-lifespan.
Finally, there are the behavioral and other risk implications of fertility, including management of ardent males and bitches in heat.
The Davis study is a significant contribution to our understanding of the unintended consequences of fertility management in a useful and popular breed. Reproductive organs contribute hormones for many reasons—it would be surprising if their removal were completely trivial. Alternatives to traditional spay/neuter do exist, but they are rarely performed. Injectable sterilizers and contraceptives are coming on the market (they, of course, will carry their own measurable side effects).
It’s important to recognize the limitations of the study: one breed, one gene pool, defined conditions and their rank among all the calamities that can befall our best friends. The study itself notes that spay/neuter is uncommon in Europe, which would appear to open up a range of comparative research possibilities and fertility management options.
We should add the Davis work to the burgeoning database. But until a lot more measurements have been taken from which broader conclusions may be drawn, the best advice is not general to all dogs, but individualized: choose your canine companions carefully and love and support them well, and completely. And recognize that we can’t measure or control for everything, yet—or ever.
Good Dog: Behavior & Training
Deciding when to euthanize
Not everybody is at ease with the idea of euthanasia under any circumstances, and I understand that. Many people have moral conflicts with deciding to end the life of a pet, no matter what the reason. My perspective is that this is a highly individual decision but that I personally am comfortable with euthanizing my pets once their quality of life is so compromised or they are in such pain that keeping them alive feels like it’s more for my sake than for theirs. It’s my view that a peaceful death by euthanasia frees them from pain and misery, and is the final gift of love I am able to provide. I know many disagree, and I’m not suggesting that one way or another is right—I’m just describing my own personal take on this issue.
That doesn’t mean that I haven’t cried buckets and been inconsolable when I’ve euthanized a dog. It’s horrible beyond imagination, and I’ve never really recovered from it in any case. I always hope for any dog (or any person for that matter) to surrender peacefully to death while sleeping. When that doesn’t happen in time, facing the tough decision of when to euthanize is a challenge. Sometimes it’s obvious when it’s time because the dog has reached a point of literally being unable to move, being in constant and unmanageable pain, showing no joy at all or no recognition of anything or anyone.
In other cases, it’s not so clear, which is why a new tool that helps guardians and veterinarians decide when that moment has arrived may be useful. Researchers at Michigan State University developed a survey for probing into the specifics of a dog’s quality of life when undergoing chemotherapy for cancer. The idea is to develop an objective way to assess quality of life, which is such an important consideration when deciding whether to continue life-prolonging measures or to face the possibility that it is time to say good-bye.
Questions address a range of behavioral issues and observations before treatment, a retrospective on the dog’s behavior six months prior, and continued observations throughout their treatment at regular intervals. The questions address aspects of dog behavior including play, measures of happiness, and signs of disease. Both guardians and veterinarians have questions to answer based on their own observations. A small pilot study of 29 dogs found high levels of agreement from clinicians and guardians. Researchers plan to expand their original work to a study with hundreds of dogs and to other illnesses and medical issues as well.
Do you think an objective tool such as this might help you decide when to euthanize a dog, or do you feel comfortable with just “knowing” when that sad day has come?
Good Dog: Behavior & Training
Science supports what we’ve long believed
Our dogs are our kids. It’s not rocket science—we love them, they love us. They look to us for comfort and care. We call them our fur kids or our four-legged children. So, even though it’s not news to us, it’s validating to see science confirm what we already thought was true: Our dogs are like children to us.
Children have been shown to explore the world most confidently if they have a strong attachment to their caregiver (usually a parent.) They use the parent as a secure base from which to explore their environment if they have learned that the parent is dependable and reliable, and this phenomenon is called the secure base effect.
In the recent study, The Importance of the Secure Base Effect for Domestic Dogs—Evidence from a Manipulative Problem-Solving Task, researchers conclude that dogs are bonded to their guardians in the same way that infants are bonded to their parents. They found that dogs use their guardians as a secure base, just as children do.
In the study, dogs were tested in each of two experiments and their behavior was quantified. In the first experiment, dogs were given the opportunity to obtain food from interactive dog toys, and the amount of time the dogs spent attempting to extract the food was recorded. The dogs were tested in three different experimental situations: 1) with their guardian absent, 2) with their guardian present and encouraging them, and 3) with their guardian present but silent and unresponsive. Researchers also recorded how much time the dogs spent in close proximity to their guardians as well as to the experimenter, who was present in all conditions.
The results of this experiment showed that the different situations had an impact on how long the dog manipulated the interactive toy in an attempt to extract the food. The dog manipulated it longer when the guardian was present than absent, but there was no difference in response to whether the guardian was encouraging the dog or remaining silent. The dogs spent an equal amount of time close to their guardian regardless of whether they were receiving encouragement or not. They spent more time close to the experimenter when their guardians were absent than when they were present, suggesting that the experimenter offered some security, social support or comfort in the experimental context.
The second experiment was designed to determine if the effects seen in the first experiment could be explained simply by the fact that in the situations in which the guardians were present, there were two people in the room, whereas in the guardian-absent condition, there was only one person. In other words, what if dogs are not affected by having their guardian as a secure base, but simply react to the presence of more than one person in the room? So, in experiment two, the first experiment was modified to include a fourth condition in which an unfamiliar person (rather than the guardian) was present along with the experimenter.
The results of the second experiment were that dogs manipulated the interactive toy longer in the presence than in the absence of their guardians, regardless of whether an additional unfamiliar person was in the room. The dogs spent more time near their silent, unresponsive guardians than to the unfamiliar person, who also refrained from interacting with the dog. The addition of the unfamiliar person condition allowed the researchers to determine that the guardian had a specific effect on the dog’s performance that cannot be explained by the presence of just any person.
Prior to participating in this experiment, all dogs were tested for their willingness to eat food in the absence of their guardians. They were also scored for their tendency to exhibit separation distress when kept away from their guardians. Interestingly, there was no relationship between the time spent manipulating the toys in the absence of their guardians and the amount of separation distress they showed, which means that the results of the experiments cannot be explained by a tendency of the dogs to manipulate the toy less because of the distress of separation.
This is the first study to demonstrate that the relationship between dogs and guardians is similar to the relationship between children and their parents in that both involve the secure base effect. This raises concerns about experiments into cognitive abilities that involve problem solving that is far more complex than in this study because the absence of guardians could significantly lower performance by the dogs.
It also confirms the view that most of us have about the canine members of our family—they are like kids to us!
News: Guest Posts
This weekend I’ll be the keynote speaker at the 5th International Symposium on Non-Surgical Contraceptive Methods of Pet Population Control. The conference title is a bit of a mouthful, but the basic idea is this: Can scientists develop a drug that will permanently sterilize dogs and cats? Or, put even more simply, can we make “the pill” for pets?
Now a lot of you may be asking, “Don’t we already have birth control for our companion animals?” Well, yes. Spay/neuter has been around for decades. But it’s not a perfect solution. For one, it’s expensive. That means not everyone can afford to sterilize their pet, even at a low-cost clinic. For another, it’s time consuming. That’s been a huge problem for non-profits trying to tackle America’s feral cat problem. With tens of millions of these felines on the streets, volunteers can’t catch and sterilize them quickly enough to keep up with their numbers. And if you think things in the U.S. are bad, consider China and India, which are home to tens millions of stray dogs that bite and spread rabies, yet these countries lack the resources to implement even meager spay/neuter programs. As a result of all of these limitations, millions of cats and dogs are euthanized in U.S. shelters every year, and millions more are shot and poisoned around the globe. If scientists could develop an injection or pill that would work as well as spay/neuter surgery, we might have a shot at eliminating the world’s homeless pet problem.
Enter the Alliance for Contraception in Cats & Dogs (ACC&D). Founded in 2000, the Portland, Oregon-based non-profit has been working with scientists and animal welfare advocates to create a non-surgical sterilant for pets. In late 2009, the mission got a huge boost from a U.S. billionaire named Gary Michelson, who announced $75 million in grants and prize money for the development of such a product. The announcement spurred dozens of research teams to begin brainstorming a solution. Some have proposed drugs that would kill the cells that produce sperm and eggs, treating them, essentially, like cancer. Others hope to go after the brain, shutting down pathways involved in fertility and reproduction. I covered these efforts in my award-winning 2009 article in Science, A Cure for Euthanasia?
ACC&D is behind next week’s symposium. It will be giving an update on these efforts and describing some new approaches to the problem of pet overpopulation. I’ll be talking about the topic of my book and what feral cats teach us about the changing status of pets in society. I hope you’ll check out the important work this organization is doing!
See more from David Grimm who is a reporter for Science magazine, you can see more from him at davidhgrimm.com
Good Dog: Behavior & Training
Similar brain abnormalities in both species
A new study has found that Doberman pinschers with canine compulsive disorder (CCD) have abnormalities in brain structure that are much like the ones in humans who have obsessive compulsive disorder (OCD). The study, conducted by eleven researchers, is called “Brain structural abnormalities in Doberman pinschers with canine compulsive disorder” and was published in the journal Progress in Neuro-Psychopharmacology and Biological Psychiatry.
The research suggests that more research about anxiety disorders in dogs may be a promising avenue for developing new ways to treat them in people. It also stands to reason that more research about anxiety in people may prove fruitful in finding new ways to alleviate suffering for dogs with similar problems.
Canines with CCD and humans with OCD typically perform repetitive behaviors. In humans, excessive hand-washing and endless checking that appliances are off or that doors are locked are common. In dogs, common behaviors are flank-sucking, blanket-sucking, licking and tail chasing. In both species, anxiety disorders can interfere with quality of life and daily routines, and can also cause injury as skin is chafed and rubbed raw by licking, washing, or sucking.
It’s no big surprise that the brains of affected individuals have similarities. After all, it has been known for a long time that members of both species exhibit related symptoms and respond to the same medications, and that there’s a genetic basis for these disorders in dogs as well as in humans. Still, the discovery that brain abnormalities are also alike adds to our understanding of the parallel nature of anxiety disorders in us and in our best friends.
News: Guest Posts
June 28 to 30—streaming live
SPARCS is a unique venture organized by Prescott Breeden and Patti Howard of The Pawsitive Packleader, Seattle Dog Training. From June 28-30, 2013, anyone in the world can see some of the leading canine science researchers in action—either in a conference hall in Redmond, WA, or streaming live to your living room.
SPARCS is short for the Society for the Promotion of Applied Research in Canine Science, which aptly summarizes the goals of the conference: (1) to promote research and education in canine science, and (2) to provide a platform for leading minds in canine science to present, discuss and debate modern behavior science.
Canine Science? Explain
If the phrase “Canine Science” gives you pause, I assure you it does not imply that dogs are meeting in the park to discuss the current issues of the day, such as:
- Owner Responses to Half Eaten Sandwiches: A Review
- Why Does the Cat Run Around at Night?: A Roundtable Discussion
- Where Are They Taking Our Poo?
Canine Science, generally speaking, is research devoted to the biology, ecology, behavior and cognition of dogs, wolves and related canids. It is a catch-all phrase that highlights the surge of research into canine minds and experiences. My article in The Bark, Dog Smart: Exploring the Canine Mind, describes this field in more detail. SPARCS brings together the following leading researchers to discuss their inquiry into the dog for a general audience:
Marc Bekoff is a long-time researcher and writer of more than 500 scientific and popular essays. In a book store? Check out one of his twenty-two books, including Minding Animals and the children’s book Animals at Play: Rules of the Game. He regularly updates a Psychology Today Blog, Animal Emotions: Do animals think and feel?
- Bekoff on dogs and their urine: Observations of scent-marking and discriminating self from others by a domestic dog (Canis familiaris): tales of displaced yellow snow.
- Bekoff on play: Social play and play-soliciting by infant canids.
Ray Coppinger has published over fifty papers on dog research. His favorite publication, however, is the book Fishing Dogs, a humorous and iconoclastic look at dogs, fishermen and professors. His book, Dogs: A Startling New Understanding of Canine Origin, Behavior & Evolution, is a classic text in the field.
- Coppinger on different behavioral sequences between dogs: Degree of behavioral neoteny differentiates canid polymorphs.
- Coppinger on improving assistance dog training programs: Observations on assistance dog training and use.
Michael W. Fox wears many hats. He is a veterinarian with a Ph.D. in medicine, and he also holds a degree in animal behavior (ethology). His career encompasses extensive research into dog behavior and development as well as holistic and integrative veterinary medicine. He encourages veterinary institutions to incorporate animal behavior and welfare science into their curricula.
- I covered Fox’s 1963 paper, Developmental Abnormalities of the Canine Skull in the Dog Spies post, Where Should Dogs Put Their Tongues?
- Fox on dog development during the first month of life: The postnatal development of neocortical neurons in the dog.
Alexandra Horowitz’s current research at the Dog Cognition Lab at Barnard College investigates animal communication and attention, dog olfaction, inter-species play behavior, theory of mind and anthropomorphisms.* She writes regularly for The New York Times, and her best-selling book, Inside of a Dog: What Dogs See, Smell, and Know, is essential.
- Horowitz on attention during dog-dog play: Attention to attention in domestic dog (Canis familiaris) dyadic play.
- Horowitz on the “guilty look” in dogs: Disambiguating the “guilty look”: Salient prompts to a familiar dog behaviour.
Kathryn Lord received her PhD in organismic and evolutionary biology, which of course means she studies wolf pups. Her research focuses on the evolution and development of dog and wolf behavior.
- Lord on sensory development of wolves and dogs: A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris).
- Lord on the meaning of dog barks: Barking and mobbing.
Adam Miklósi leads the Family Dog Project at the Department of Ethology at Eötvös
Loránd University in Budapest, where I had the pleasure of conducting my Masters research (covered on SciAm by Jason Goldman of The Thoughtful Animal). In the last 15 years, the Family Dog Project research group has published over 100 scientific papers and organized the inaugural Canine Science Forum in 2008. His book, Dog Behavior, Evolution and Cognition is required reading in canine ethology.
- Miklósi on the building blocks of meaningful social interactions: On the utilization of social animals as a model for social robotics.
- Miklósi on other species’ use of human communicative gestures: A comparative analysis of animals’ understanding of the human pointing gesture.
Monique Udell has worked with a variety of species such as wild cats, megachiropteran bats, coyotes, foxes, mice, non-human primates and a range of companion animals including dogs, cats, and ferrets. She has a special interest in how the cognition and behavior of domestic dogs and wolves can be altered by lifetime experience.
- Udell on dog sensitivity to human behaviors: What did domestication do to dogs? A new account of dogs’ sensitivity to human actions.
Before Clive Wynne found a way to combine a childhood fascination with dogs with his day job as a psychology professor, he studied the behavior of animals ranging from pigeons to dunnarts (a mouse-sized marsupial) at universities in Britain, Germany, the USA, and Australia. Now head of the Canine Cognition and Behavior Laboratory, he is full of tales of everything from the tame foxes of Siberia to the dogs of the Moscow subway.
- Wynne on anthropomorphism: What are animals? Why anthropomorphism is still not a scientific approach to behavior.
- Wynne on the relationship between companion dogs and children: The other side of the bond: Domestic dogs’ human-like behaviors.
So, What’s This Conference About?
The SPARCS conference investigates dogs from three angles: “Origins in the Wild,” “Social Behavior and Emotions” and finally “Cognition and Development.”
Origins in the wild
“It is widely accepted that dogs are descended from wolves, but that is about the only uncontroversial fact about the origins of dogs…. I have come to a new proposal for the origin of dogs.” Clive Wynne
“In my presentation I shall talk about the emotional lives of nonhuman animals (animals) – beastly passions – and how they very much care about how we treat them.” Marc Bekoff
“The modern wolf and the modern dog diverged into their present forms, sometime, somewhere, and somehow. We should discuss those when, where, and how questions.” Ray Coppinger
Social Behavior and Emotions
“I shall also talk about why play has evolved – what it is “good for” and why it is very important that we come to terms with the details of what animals do when they play.” Marc Bekoff
“So the basic question is: What makes a dog skillful for living in the anthropogenic [human] environment, and whether we can claim that there is a parallel between some of the behavioral skills of dogs and those of humans?” Ádám Miklósi
“Dogs are socially and emotionally promiscuous and, given the right conditions, can form attachments to members of many other species.” Clive Wynne
Cognition and Development
“How the dog’s brain and behavior develop is integral to our understanding of critical and sensitive periods in helping facilitate a strong social bond and in enhance learning/trainability, emotional stability and stress & disease resistance.” Michael W. Fox
“[W]e must be careful not to forget the true diversity of the domestic dog population, or assume that the sum is more representative than its parts. Indeed, it is at the fringes of the species where we often discover examples of amazing cognitive feats, or hidden canine capacities unveiled by unique environmental or experiential contexts.” Monique Udell
“First, I aim to highlight and examine the attributions we unthinkingly make to dogs. Second, I use findings about the biology and cognition of dogs to create a better picture of the dog’s experience: the umwelt, or point of view.” Alexandra Horowitz
What About My Living Room?
Because SPARCS aims to make continuing education accessible, the conference will be broadcast live and free of charge: “As long as you have a computer, a tablet, or a smartphone, everyone will be able to watch our broadcast from anywhere in the world.”**
SPARCS plans to be a yearly conference, so keep it on your radar!
Ticket, Live Stream and Schedule
on Social Media
SPARCS on Facebook
SPARCS on Twitter
All photos courtesy of SPARCS
** SPARCS adds, “Donations are absolutely optional however graciously appreciated. If you watched our event online and enjoyed it, consider donating to SPARCS.”
Dog Smart: Exploring the Canine Mind at The Bark
Talking dogs: Welcome to the 3rd Canine Science Forum at Dog Spies
Inside the 3rd Canine Science Forum at Dog Spies
This story was originally published by Scientific American. Reprinted with permission.
About the Author: Julie Hecht is a canine behavioral researcher and science writer in New York City. She wriites a behavior column for The Bark. She would really like to meet your dog. Follow on Twitter @DogSpies.
Culture: Science & History
Village dogs’ genetic code may hold clues to canine evolution and health
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.
Good Dog: Behavior & Training
Benefits of lower protein and higher fat
It’s not news to anyone that the food that we feed our dogs matters. The right food may translate to better health, proper weight management, longer life, a shinier coat, and better performance in a range of sports and activities. New research suggests that the diet of working detection dogs can even have an impact on their ability to smell.
Joseph Wakshlag at Cornell and his colleagues at Auburn University found that dogs who were fed more fat and less protein than typical diets contain were better able to detect certain scents such as TNT, ammonia nitrate and smokeless powder. Over a year-and-a-half, they rotated dogs through three diets and compared their detection abilities when they were on each diet. The three diets were: 1) a high quality performance diet, 2) regular adult dog food and 3) regular adult dog food combined with corn oil. The ability to detect scents was highest when the dogs ate the diet of regular dog food combined with corn oil. That diet had less protein but the same amount of fat as the high performance diet. The high performance and regular diets had equal amounts of protein, but the high performance diet had more fat.
Digesting protein causes a rise in a dog’s body temperature, as does exertion in the form of physical activity. The panting that is essential for lowering body temperature reduces a dog’s ability to smell well. In order to do their detection work as effectively as possible, dogs must cool down so that they are not panting. A diet higher in fat and lower in protein seems to allow dogs to cool down faster and therefore smell better.
What constitutes a high performance diet may depend on the sort of performance that is desired. Dogs who work by running or pulling hard may need more protein to succeed at their job than dogs who need to be able to maximize the effectiveness of their olfactory abilities.
Good Dog: Behavior & Training
Its association with lifespan and cause of death
In a new study called Reproductive Capability is Associated with Lifespan and Cause of Death in Companion Dogs, researchers report on the links of reproductive status (intact or spayed/neutered) with both lifespan and cause of death. Previous studies have suggested that sterilization increases the risk of certain cancers. However, if spaying and neutering actually does increase life span, then any cancers that are more common in older dogs may only appear to be more common in sterilized dogs because sterilized dogs live longer.
The overall conclusions of this new study are that there is a link between lifespan, cause of death and reproductive status. Sterilization was associated with longer lifespan. The mean age of death for intact dogs was 7.9 years and for sterilized dogs was 9.4 years. Sterilization increased life expectancy 13.8% in male and 26.3% in females.
In this study, researchers found differences in the cause of death between the reproductively capable group and the sterilized group. Compared to reproductively capable ones, dogs who were spayed and neutered were more likely to die of cancer and immune-related diseases, but less likely to die from infectious diseases, trauma, vascular disease and degenerative diseases. These differences in causes of death were consistent when the data were compared between dogs of the same age.
Data are from 40,139 dogs in a veterinary teaching hospital who died from 1984 to 2004. Juvenile dogs, dogs with a congenital issue that caused death, and dogs whose reproductive status, cause of death, or age were unknown were eliminated from the over 80,000 dogs originally considered for inclusion in the study. Reproductive capability was defined in this study as intact versus spayed or neutered, and does not mean the sterilized dogs had not reproduced. It’s unknown if they had reproduced prior to being sterilized. There were no data on how many times intact dogs had reproduced, only that they were still reproductively capable.
Though the results of this study are intriguing, it is important to recognize the limitations in the data and therefore in the conclusions. Though the groups—intact or sterile—are assumed to differ in no other way, that may not be the case. It is possible that the members in the sterilized group have received more regular or better medical care throughout their lives, for example. The sterilized dogs may come from different sources such as rescue groups or shelters rather than from pet stores or breeders. In other words, differences in life span or cause of death may not relate to reproductive status, but to one of these other factors. This study shows links of reproductive status with lifespan and cause of death, but we cannot assume that reproductive status is the cause of these differences. They may be correlated for some unknown reason.
Some other concerns I have about the data are that the dogs had all been referred to a veterinary teaching hospital for medical reasons, which means that the dogs in the study may be largely dogs with serious health issues rather than typical dogs. This means that conclusions based on this study may not be applicable to dogs in general.
I’m glad that studies are expanding on the question of lifespan and reproduction by looking at causes of death instead of just reproductive capability. I think this study is a great start at exploring questions that are of interest to all of us who love dogs, but I do think we need to exercise caution in order to make sure that we are distinguishing between studies that show correlations between various factors and those that demonstrate a causal relationship between those factors.
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