News: Karen B. London
Recent research contradicts prevailing wisdom
It’s hard to make sense of the great number of contradictory studies about the effect of black coat color on the time it takes for shelter dogs to be adopted and the likelihood of them being euthanized. There have been many studies suggesting that having a black coat is bad news for shelter dogs, and some suggesting that black fur is not important in these ways.
It continues to be reported in the media that it is hard to adopt out black dogs, and many spokespeople for shelters and rescues discuss this at length. Yet, the data are not consistent across studies. One study called Investigating the role of coat colour, age, sex, and breed on outcomes for dogs at two animal shelters in the United States that came out recently in the journal Animal Welfare is one of the studies I take the most seriously. The researchers conclude that while age, sex and breed affect adoptability and likelihood of euthanasia, having a black coat color does not.
There are a number of reasons why I think highly of this research. It includes data from over 16,000 dogs from two shelters during a four-year period, which is longer and larger than most studies of its kind. One shelter chooses which dogs it admits and one has an open admission policy, meaning that it takes in any dog that arrives at its doors with no selection based on age, appearance, medical issues or behavior. The data include how long each dog was available for adoption, and whether or not the dog was eventually adopted, was euthanized or died in the shelter. Some studies have included the time that dogs were held for various reasons but not available for adoption, which could introduce biases against black dogs. It looked at euthanasia rates as well as the number of dogs of different colors that entered each shelter. It considered breed, age and size as well as coat color.
It may sound like an obvious way to conduct research, but this study looked at actual data from shelters instead of considering opinions on black dogs in interviews. The difficulty of adopting black dogs that is commonly reported in the media is often based on a study that interviewed people working in shelters and rescues. A majority of the people in that study reported that large black dogs were more difficult to place than other dogs. This is problematic because of the opinion aspect of the study and because of the lumping of size and coat color.
Despite the mixed findings across studies about the adoptability of black dogs, it is no surprise that there is a perception of bias. A number of studies have shown that people have a negative view of black dogs, considering them less agreeable, less conscientious and less emotionally stable than dogs of other colors. Perhaps more alarming, another study found that people selected large black dogs as representative examples of dangerous and aggressive animals. In support of negative views of black dogs, another study found that people were more likely to change their path in response to a black dog than in response to a pale dog, regardless of size. Not surprisingly, there are contradictory studies in this area, too. For example, one study found that people considered black poodles friendlier than white poodles.
Overall, this recent study concluded that the dogs who were more likely to be euthanized than expected if such decisions were random were dogs that were 10-12 years old, male dogs, members of bully breeds, and brindle dogs. The length of time a dog had to wait to be adopted was also affected by many factors. The dogs who were adopted most quickly were females, young dogs, yellow, grey or black dogs, and terriers or toy breeds.
There are so many factors that can influence intake and euthanasia decisions by shelter staff and adoption choices by guardians. The idea that black dogs are difficult to adopt, though the data have been so variable on this point, may actually influence people into adopting a black dog. Many adopters prioritize choosing a dog who may not otherwise find a home, and this may mean that such people are gravitating towards black dogs.
I’m certain that there will be more research about the dogs that adopters choose, so we are sure to learn more about the effect of various factors on both adoption and euthanasia.
Wellness: Health Care
Take a Deep Breath
Somewhere in northern California, a tiny dog is still prancing around on four paws thanks to hyperbaric oxygen therapy (HBOT). Unbeknownst to the dog’s owner, a piece of string had become wrapped around his paw, hidden in the dog’s dense fur. As circulation in the paw slowed down, skin and tissue began to slough off. By the time the owner realized what was happening, the paw was in such bad shape that the little dog’s vet, understandably, recommended amputation. The owner, however, wanted to try to save it. After a strict regimen of cleaning and dressing changes failed to promote significant improvement, the dog was referred for HBOT treatment.
Deep-sea and scuba divers have long used HBOT to combat the bends, and in the medical arena, it has been employed for more than 50 years to help people recover from serious infections and hard-to-heal wounds, among other ailments.
Now, this technology is being utilized to help companion animals and horses with conditions as varied as head and spinal-cord trauma, intervertebral disc disease, wounds and burns, infections, and inflammatory conditions.
The general theory behind HBOT is that it promotes healing by raising oxygen levels in the blood, allowing oxygen to diffuse into tissues at distances three to four times further than usual. Gary Richter, MS, DVM, medical director of Holistic Veterinary Care and Rehabilitation Center, Oakland, Calif., is among those who use HBOT in their practices. According to Dr. Richter, “When there’s inflammation, damaged tissues or injury, lack of oxygen is very commonly the limiting factor. By increasing the amount of oxygen delivered to tissues, we are stimulating these patients’ own healing abilities—immune systems, stem cells—to begin the healing process where other types of conventional medicine might not be able to achieve that goal.” (The dog with the damaged paw was treated at Dr. Richter’s clinic.)
Typically, HBOT treatments last about an hour and are given one to two times daily. A patient is placed in a hyperbaric chamber and breathes 100 percent oxygen at 1.5 to 3 times normal atmospheric pressure. The total number of treatments required depends upon the condition and how the patient responds. Being enclosed in the chamber doesn’t seem to distress the dogs or cats who use it; many reportedly go to sleep during treatment. Dr. Richter thinks that for the patient, it’s mainly boring; “as far as the animal’s concerned, nothing’s happening.” The cost and protocol are the same no matter how large or small the patient.
The therapy has essentially no side effects, although Dr. Richter says that it’s also important to select HBOT candidates appropriately. Dogs or cats with some types of respiratory problems or who are predisposed to specific types of seizures need to be evaluated before undergoing the therapy.
And sometimes, says Dr. Richter, the therapy may have positive side effects. Take, for example, the case of a cat with inflammatory bowel disease (IBD) so severe that she required a surgically implanted feeding tube. The surgical site became infected with Methicillin-resistant Staphylococcus aureus (MRSA), a bacterium responsible for several difficult-to-treat infections. HBOT was used to help the site heal and resolve the MRSA, but as a side effect, her IBD improved to the point that she no longer required intensive medical monitoring.
Despite being approved for use in humans for an array of medical conditions, HBOT is not without its skeptics, who say that the lack of clinical trial data supporting its claims puts it into the realm of experimental. However, based on the human experience, it would seem that HBOT has the potential to become another valuable tool in the veterinary health-care toolbox.
News: Karen B. London
Do dogs prevent anxiety?
Kids who are asking their parents for a puppy this season have a convincing new argument to try. A recent study ("Pet Dogs and Children’s Health: Opportunities for Chronic Disease Prevention?”) reports that kids who live with a dog are less likely to be anxious than their peers living in homes without dogs. Researchers evaluated 643 children for signs of anxiety. They found that only 12 percent of kids who have dogs met the clinical criteria that would prompt health care professionals to further screen for anxiety. This was in contrast to 21 percent of kids without dogs who met those criteria.
Despite the way this study has been reported in the media, the authors of this study do not claim that there is a causal relationship between having a dog and lower levels of anxiety in children. Sure, if you are reading this, you are all but certainly a dog lover and inclined to see the benefits of being with dogs. There’s plenty of scientific evidence to back you up if this where you stand. Being with dogs can lower levels of cortisol (which is associated with stress), decrease blood pressure and heart rate, and increase levels of oxytocin (which is associated with social bonding.)
The study highlights the correlation between living with a dog and a lower likelihood of anxiety in children, but makes no claims about why the association exists. It is entirely possible, for example, that people who are less anxious by nature are more likely to have dogs, and their children just happen to share a lower likelihood of anxiety. Or perhaps people with children tend to get dogs only when their lives are not too stressful, which means that the people with and without dogs vary in their anxiety levels for reasons that are not related to having dogs.
It seems highly possible that living with a dog lowers the risk of anxiety in children, perhaps by alleviating loneliness and separation anxiety or by facilitating social interactions. Still, it’s important to understand that the links found in this study do not show the presence of the dog to be the key factor.
While I would not recommend that anyone rush out to acquire a dog for the sole purpose of lowering their children’s chances of developing anxiety, kids might try to convince you to do exactly that. They may have a point.
Good Dog: Behavior & Training
Links between canine lateralization, behavior and emotion
A few years ago, dog trainers and behaviorists renewed their love affair with tail-wagging, constantly checking to see whether dogs were wagging their tails higher to the right or to the left. Our awkward attempts at positioning ourselves to observe this behavior were surely entertaining to others. Why were we so eager for the information conveyed by these asymmetrical tail wags? Because they indicate dogs’ differential use of the left and right hemispheres of their brains and are, therefore, a window into their emotions.
The study of asymmetrical tail wagging that prompted our collective interest (Quaranta et al. 2007) found that differences depended on what inspired the wags in the first place. Dogs wagged higher to the right when greeting their guardians. The same right-side bias was seen in response to unfamiliar people, although the wags were lower overall. In response to cats, there was little wagging, but it was still higher to the right. In the tests, the only stimulus to which dogs’ wags had a left-side bias was an unfamiliar, confident dog.
Left or Right?
The left hemisphere is activated when the brain is processing positive experiences associated with emotions such as happiness, affection and excitement, as well as anything familiar. The right hemisphere takes precedence when processing sadness, fear, other negative emotions and novel things.
This link between emotions and sides of the brain came to light in studies of humans. Ahern and Schwartz (1979) found that people who were asked questions that elicited either positive or negative emotions responded in accordance with this principle. They looked to their right (showing left brain hemisphere involvement) in response to questions that elicited positive emotions, but looked to their left (showing right brain hemisphere involvement) in response to questions that evoked negative emotions.
Individuals—canine or human—who favor the left paw or hand more often use the right hemisphere of their brain, while right-pawed and right-handed individuals have a more active left-brain hemisphere. Studies have shown differences between right-pawed and left-pawed dogs. They have also revealed that dogs who are ambilateral—who don’t have a paw preference—are different in predictable ways from dogs who strongly prefer one paw over the other.
Lateralization research, an active area of study, informs our understanding of emotions and behavior. Though dogs and people are common study subjects, similar patterns have been found in fish, amphibians, reptiles, birds, and primates and other mammals.
Determining Paw Preference
Strength of Lateralization
Batt et al. (2009) showed that dogs with stronger paw preferences were bolder and less cautious than dogs with weaker paw preferences. They were more confident, less prone to arousal and anxiety, quicker to relax or become playful in new environments, and exhibited calmer responses to novel stimuli and strangers. It turns out that we humans are similar to our best friends in this regard: People with weak hand preferences are more likely to suffer high anxiety levels and are more susceptible to both PTSD and psychosis than those with a strong handedness.
Just as being right-pawed predicted guide-dog training success, dogs with a strong lateralization (either left or right) and a low rate of using both paws in the Kong test fared better in these programs (Batt et al. 2008). The authors hypothesize that this may be because strongly lateralized and right-pawed dogs are less likely to experience high reactivity and distress responses, which are detrimental to success as a guide dog.
Dogs also turned left in response to images of cats and snakes but not to images of dogs. With repeated presentations, there was a change toward right-turning behavior, indicating that the left side of the brain and its associated positive emotions were involved. This suggests that novelty may be a factor in fear and other intense negative emotions that tend to be processed by the right side of the brain.
To understand the role of lateralization in processing olfactory stimuli, it is essential to know that each side of the brain processes the information received on the same side: the right nostril goes to the right hemisphere, the left nostril goes to the left hemisphere. Dogs started to sniff novel but non-aversive stimuli (food, lemon, dog secretions) with their right nostril and then shifted with repetition to using their left nostril, showing a change from negative to positive emotions. When presented with adrenaline and sweat from their vets (really!), dogs demonstrated a consistent bias toward the right nostril, suggesting that their emotions started, and remained, negative in response to these odors (Siniscalchi et al. 2011).
* * * * * * *
Love and understanding compound one another with our dogs, and lateralization is a case in point. A dear dog friend of mine is strongly right-pawed; it was pitiful to watch him attempt to learn to give a left high-five, or use his left paw to hold his Kong when he briefly had a bandage on his right paw. I used to find how hard it was for him to do anything with his left paw somewhat comical. Now I understand that this trait is part of the package that makes him the unflappable, happy, don’t-care-about-the-power-tools-running-all-day-during-the-kitchen-remodel, playful and exploratory, nothing-fazes-him kind of dog I love so much. I’m honored and overjoyed that when he greets me, his tail wags are as one-sided to the right as the rest of him.
A gathering of ideas
There is an astounding amount of research on dogs—academic studies, medical research, social and psychological testing, not to mention reams of data gathered from our everyday lives. Thoughtfully assimilated, all of this information can help us and our dogs live better lives together.
I was reminded of how fortunate dog enthusiasts are to share in this wealth of information upon my return last week from Purina’s Better with Pets Summit (November 3). The annual event, this year presented in Brooklyn, NY, was a gathering of pet experts sharing their latest findings with the media. The theme for the day was “exploring the best ideas for bringing people and pets closer together.” It was an apt description.
The day started out with an inspired presentation by Dr. Arleigh Reynolds, a veterinarian and research scientist who studies the impact of nutrition on performance on sled dogs. A champion musher himself, Reynolds’ talk focused not on a program he’s involved with in the Alaskan village of Huslia. This small coastal community was the home of George Attla, a famed champion musher and native Athabascan who ruled the sport for thirty years before retiring. In honor of his son Frank, who died at age 21 in 2010, Attla started the Frank Attla Youth and Sled Dog Care Mushing Program. The program serves many purposes—providing skills, lessons in cultural traditions, and a sense of belonging to the youth population while uniting all townspeople around a common activity, mushing. The program, as described warmly by Reynolds and in a short documentary film demonstrates the power that dogs can initiate in our lives.
Next up was a panel discussion titled “Are Millennials Changing Our Relationships with Cats?”—offering the interesting observation that a new generation of cat people have now formed a community on the internet—so as dog people connect at dog parks, cat lovers now interact online sharing their passion for felines. We met Christina Ha, the co-founder of Meow Parlour, New York’s first cat café. Can a canine café be in our future?
The most anticipated panel “Stress, Our Pets, and Us” featured animal behaviorist Ragen McGowan, PhD; architect Heather Lewis (Animal Arts) and Dr. Tony Buffington, professor of veterinary science. McGowan discussed the value of having dogs work for their food citing her studies with grizzlies, chickens and mice on the practice of contrafreeloading (working for food when food is freely available). Lewis’s architectural practice specializes in designing veterinary hospitals and animal care facilities around the country, meeting the unique needs of both workers and animals. It’s evident that good design can have an important impact on animal friendly environments—from soothing color palettes to calming lighting levels or the simple use of horizontal bars (less stress inducing) instead of traditional vertical bars. The key takeaway: Mental exercise for animals might be as important to their well-being as physical exercise.
“Raising Pets and Kids” featured Jayne Vitale of Mutt-i-grees Child Development Director; Ilana Resiner, veterinarian behaviorist; and Charley Bednarsh, Director of Children’s Services (Brooklyn). The Bark features an in-depth article in its Winter 2015 issue on Mutt-i-grees, a program developed by the North Shore Animal League that offers academic and emotional support to students from kindergarten through high school, teaching them how to be ambassadors for the humane treatment of animals. Bednarsh and her therapy dog Paz, team up to assist young witnesses of domestic violence navigate the judicial system (a similar program first reported in The Bark). We were reminded of the important contribution to the health and well-being of the children in these extraordinary programs, and also to common households. Note to self: Don’t humanize your dog—study, understand, embrace their dogness.
The afternoon offered a room full of experiential exhibits—interactive displays that provided lessons in healthy environments, cognition, reading your pet, nutrition and your pet’s purpose. Manned by teams of experts, the well designed displays presented an immersive course in Dog and Cat 101. I’d love to see the exhibits showcased to the general public, those most in need of education and guidance in the proper care of pet companions. The day was rich with ideas and notes that we’ll shape into future articles for The Bark.
Purina’s commitment to offering a forum of ideas is commendable. In a similar vein, the company hosted another notable event on November 7—a free live video cast of the Family Dog Project from Hungary—with over a dozen presentations by leading scientists and animal behaviorist exploring everything from canine cognition to sensory perception in dogs. Like the Pet Summit, it was a fascinating collection of concepts and dialogue, enriching to everybody who participated.
For more check out #BetterWithPets
News: Karen B. London
Effects of feeding frequency and age
When and how much our dogs sleep matters to us because it affects our own sleep. Most people who have ever raised a puppy know the horror of sleep deprivation, and many people caring for elderly dogs or those who are unwell are facing the same problem. Even dogs who don’t need to be taken out in the middle of the night or in the wee hours of the morning often work against the goal of an uninterrupted stretch of eight hours of restorative sleep each night.
I once had a dog who slept in every morning, and I valued that quality in him immensely. Though I made many attempts to figure out how to transfer this quality to all dogs, I suspect he just came into the world that way. True, we did feed him healthy food and give him lots of exercise, but that surely hasn’t worked on a large number of other dogs. Still, I maintain a strong interest in learning about the variables that affect dogs’ sleep patterns, with the eventual hope that dog guardians everywhere can apply it to their own dogs for the benefit of all.
Because I am interested in canine sleep, I was interested in a study that investigated some basic aspects of dogs’ sleep patterns. The research looked into the effects of age and feeding frequency on dogs’ sleep patterns. Dogs were in one of three age ranges (1.5-4.5 years, 7-9 years, 11-14 years) and were fed either once or twice daily.
The researchers found that older and middle aged dogs slept more during the day than young adult dogs, but that was because they took more naps, and not because their naps were longer. Older and middle aged dogs also slept more at night than younger dogs because they had a longer total sleep interval at night (waking up later) and woke up fewer times during the night.
Dogs of all ages were affected in a similar manner by being fed twice daily as opposed to once a day. Dogs who were fed more frequently took fewer naps during the day, but the naps lasted longer. Dogs fed twice a day fell asleep earlier at night, but woke up earlier, too with a decreased total time sleeping at night. (The earlier waking time more than compensated for the earlier bedtime.)
>The take home message to me is that if you want more sleep, just wait until your young dog ages a little. That’s interesting when you compare dogs to humans, because we sleep considerably less as older adults than as young adults.
Have you noticed a change in your dog’s sleep pattern with age or with changes in feeding schedules?
A romp at the dog park, a run along a trail, a walk around the neighborhood--we know how important it is to get our dogs out and about. But how often do we think about exercising our dog's brain? And really, why should we think about it at all?
Recently, I listened to an online seminar offered by Karen Overall, MA, VMD, PhD, DACVB, CAAB, and board certified Applied Animal Behaviorist, that provided several answers to this question.
Dr. Overall starts out by making the interesting point that it's very likely that dogs co-evolved with humans, which was made easier because both species have similar social systems that rely on work and problem-solving. Dogs still need to problem solve but in today's world, probably don't get enough opportunities to do it, which is why we need to provide them with mental stimulation as well as physical exercise.
She then discusses some of her research and shows videos of dogs working a puzzle box designed specifically for one of her projects; she also analyzes what the dogs' performance indicates about their emotional state.
The takeaway is that stimulating a dog's brain by engaging his capacity to problem solve improves both his physical and mental health. It's also key to helping dogs with behavior problems learn new ways to respond to stress.It's science nerd nirvana, a combination of theory and practical advice (most of which comes at the end in the Q&A segment).
The seminar is titled From Leashes to Neurons: The Importance of Exercising Your Dog's Brain for Optimal Mental and Physical Health, and you'll need to register to listen in (registration is free). Get started here: http://vetvine.com/article/192/akcchf-human-animal-bond-event
News: Karen B. London
Human behaviors that precede them
One disadvantage of being a canine behaviorist is that so many human behaviors scare me. My heart leaps into my throat all too often when I see people performing risky behaviors around dogs. From hugging dogs and picking up dogs to sticking their faces right by a dog’s face or bending over a dog, there are plenty of gasp-worthy moments. I see people performing these behaviors and want to scream out a warning. It’s similar to the reaction I have when watching a horror movie and want to yell, “Don’t go in the house!”
I work with so many clients whose dogs have bitten someone, and as I hear the stories of the bites, the same human behaviors are mentioned over and over. I’m not saying this to blame the people, but rather to help us all learn how to lower our risk of being bitten.
Dog bites are a serious problem that we should all attempt to avoid, and among the most distressing are bites to the face. In a new study called Human behavior preceding bites to the face, scientists examined 132 incidents of bites to human faces that did not involve bites to any other parts of the body. The goal of the study was to determine the human behavior that preceded bites.
Well-know risky behaviors such as bending over a dog, putting the face close to a dog’s face and eye contact with the dog and person very close to each other did occur before many of the bites, which is no surprise. What was a bit of a shock was the percentage of times that these no-no behaviors happened before the 132 incidents in the study. In 76 percent of the bites, people bent over the dog just before the bite! In 19 percent of the cases, a bite was preceded by people putting their faces close to the dog’s face, and in five percent of the cases, gazing between dog and person at close range occurred before a bite. In no incidents was a bite to the face preceded by trimming the dog’s nails, falling on the dog, hitting the dog as punishment, stepping on the dog, pulling the dog’s hair, tugging the dog’s body or scolding the dog.
More than 75 percent of the bites to the face happened to people who knew the dog. Over two-thirds of the bites were to children, and of those, 84 percent were to children under the age of 12. Children who were bitten were with their parents in 43 percent of the cases and with the dog guardian in 62 percent of the incidents. Sixty percent of the bites were to females, and no adults were bitten by their own dogs. More than half of the bites were to the nose and lips of the person, as opposed to the chin, cheek, forehead or eye area.
All of the dogs who bit someone in the face were adult dogs, and over two-thirds of them were male dogs. In only six percent of the bites did people report that the dog gave a warning such as growling or tooth displaying prior to biting. (To me, this is the single most surprising finding in the study, and I think it’s quite possible that some people did not notice or failed to remember warnings by dogs.)
As the authors of the paper mention, this research is based on questionnaires that ask people about past events. As such, there are inherent limitations with the study. Still, the results about the frequency with which kids are bitten, the greater likelihood of male dogs biting faces than female dogs, and the finding that only adult dogs bit faces are consistent with previous research.
If you have ever been bitten in the face or seen it happen to someone else, what do you remember about the human behavior right before the bite?
News: Karen B. London
Dogs vary in their view of the world
If you think all dogs are cheerful, upbeat and excited about what life has to offer, you’ve either interacted exclusively with optimistic dogs, or you haven’t noticed that some dogs are a little more on the “food bowl half empty” side of the personality spectrum. Not all dogs are quite as happy-go-lucky as we humans generally assume.
The idea of individual personalities in dogs is hardly stop-the-presses news anymore, but studying such differences in dogs is still a fruitful area of research. In a 2014 study published in PLOS, a group of scientists studied judgment bias in dogs to investigate individual tendencies to view the world optimistically or pessimistically.
To study dogs’ expectations of the world, they trained them to associate different sounds with different outcomes. One sound let them know that touching a target would result in receiving the preferred reward of milk. The other sound, two octaves apart from the milk sound, indicated that they would get the less desirable reward of an equal amount of water. The correct response to the water tone was not to touch the target. Once dogs could easily distinguish between these two sounds, the real test of their personalities began.
Trained dogs were given a tone that was between the two trained tones, and their response was observed. Dogs who reacted to the ambiguous tone by pushing the target in anticipation of milk were considered optimists. They expected good things to happen. Dogs who failed to respond to the ambiguous tone were considered pessimists in that they did not have an expectation of good things. They were not filled with the hopefulness of the optimists in the study. This study allowed researchers to determine whether individual dogs have the expectation of positive outcomes or whether they expect negative outcomes.
Some dogs would respond to ambiguous tones even if they were more similar to the water tone than to the milk tone. These dogs were considered extreme optimists. Overall, researchers found that more dogs were optimists than pessimists. I find that reassuring since it matches the way most of us view dogs.
What do you think this test would reveal about your dog?
News: Guest Posts
With their extremes of limb and coat, purebred dogs may seem more prone to health problems. And don’t breeders even compound defects, as they tinker with uniformity? Yet the dog of many varieties, a potluck of traits, outlasts them all.
Not quite, say U.C. Davis researchers in a recent study lead by Anita Oberbauer in Canine Genetics and Epidemiology. Their analysis of health records of 88,635 dogs, both purebred and mixed breeds, tilts assumptions. So does another recent study, in which they found both populations shared similar risk for 13 inherited disorders. One condition was even more prevalent in mixed-breeds.
Purebreds, and their health records, have made it easier to explore the genetics of diseases that get passed down, the researchers say. But as we hear about the studies, the belief that purebreds are less healthy grows. In fact, many breeds have proven more prone to some diseases, like Great Danes and hip dysplasia.
In this study, they sliced the data thinner. Could particular AKC breed groups, not just individual breeds, be the source? Do the diseases arise from dogs with genomic similarities like working and herding groups? The huge pack of canines, seen over 15 years at U.C. Davis veterinary teaching hospital, showed that ten inherited conditions are more common in purebred dogs. But surprise, not all purebred dogs.
A subset of pedigreed pups tied with mixed breeds for the disorders.
The conditions include aortic stenosis (narrowing above the aortic heart valve or of the valve); skin allergies; bloat; early onset cataracts (clouding of the lens inside the eye); dilated cardiomyopathy (enlargement of the heart chambers); elbow dysplasia (abnormal tissue growth that harms the joint); epilepsy (brain seizures); hypothyroidism (underproduction of thyroid hormones); intervertebral disk disease (affects the disks of the spine, causing neurological problems); and hepatic portosystemic shunt (abnormal blood circulation around the liver, rather than into it).
With a spotlight on the ten maladies, the researchers set out to learn which canines are more at risk. Purebreds were subdivided into categories, then compared to the mixed breeds.
For three conditions common across the purebreds—skin allergy, hypothyroidism, and intervertebral disk disease—many groups had higher prevalence than the mixes. But for seven others, most purebred groups were statistically neck and neck with mixed-breeds. (Aortic stenosis, gastric dilation volvulus, early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, and portosystemic shunt).
Terrier groups even bested the mixes for one problem, having less intervertebral disk disease.
Among the purebred groups, health differences were clear. Compared to mixed breeds, terriers and toys were more likely to have two disorders. Herding and hound groups were more burdened with four conditions. The non-sporting group, where pooches ranging from Poodles to Dalmatians fit in, were more likely to have five disorders. Working breeds, animals expected to have grit and vigor; six. Worst in health: the sporting group bred for outdoor stamina. They were more at risk for seven inherited disorders.
In fact, in three categories of dogs bred for endurance—herding, sporting, and working AKC groups—aortic stenosis, the heart condition present at birth, was higher. With narrower focus, other findings emerged. The researchers say the data “suggests that most breeds in the herding group are not at higher risk”—except the German Shepherd, which other studies have also found susceptible.
And while Retrievers were more affected by aortic stenosis, another sporting breed, the Spaniel, wasn’t. For a different malady, Spaniels were the unluckiest. Epilepsy was more prevalent in herding, hound, and sporting groups, particularly the Spaniel breeds.
Early onset cataracts beset both non-sporting and sporting breeds more often.
How did all of these health glitches arise? The study mentions other research that found some diseases, like elbow dysplasia, are more frequent in dogs of related ancestral origin. The so-called “liability genes” may hail from founding ancestors of related breeds, or be the result of human error in the quest for desired traits. This study, the authors say, “may shed light on the possible origin of certain inherited disorders in domestic dog evolution.”
For the ten diseases, the analysis found some purebreds genetically healthier than others. Flipped around, mixed breeds were no healthier than certain purebreds. But both populations may benefit from the work. According to the researchers, defining the lineage associations for such disorders may bring about new therapies.
Better, it could allow breeders to weed out the responsible genes to begin with. Especially at the local level. “Whether breeding reforms will mitigate inherited disorders in mixed-breeds will depend upon the locale,” the scientists say. That is, some regions have a greater potluck of breeds within their mixed-breeds.
Still, since most mixes have purebred ancestors, they say, improvement of the genetic health of purebreds “may trickle down to mixed-breed dogs.”
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