Tag Archives: genetics

Demography and disorders of the French Bulldog population

French Bulldogs, predicted soon to become the most popular dog breed in the UK, are vulnerable to a number of health conditions, according to a new study published in the open access journal Canine Genetics and Epidemiology.

Researchers at The Royal Veterinary College (RVC), UK found that the most common issues in French Bulldogs over a one year period were ear infections, diarrhea and conjunctivitis (inflammation of the eye surface).

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French Bulldog puppy. Credit: © Mary Swift / Fotolia

Dr. Dan O’Neill, RVC Senior Lecturer and the main author, said: “French Bulldogs are a relatively new arrival to the list of common UK breeds so there is very little current research on them in the UK. Our study — the first on this breed in the UK — is based on anonymised records gathered from hundreds of UK vet clinics. It provides owners with information on the issues that they could expect and should look out for in French Bulldogs. It may also help potential new owners to decide if a French Bulldog really is for them.”

Dr. O’Neill adds: “One of the interesting finding from our research is that male French Bulldogs appear to be less healthy than females. Males were more likely to get 8 of the 26 most common health problems while there were no issues that females were more likely to get than males.”

The authors suggest that the distinctive appearance of the French Bulldog, with their short muzzles and wide, prominent eyes, may be a key factor influencing their popularity. However, these characteristics may also increase the risk for some of the health problems seen in French Bulldogs. For example breathing issues, seen in 12.7% of the dogs in this study, are a known problem in breeds with short noses and flat faces. Skin problems overall were the most common group of health issues and the authors suggest that this may be due to the skin folds that are characteristic of the breed.

Dr. O’Neill said: “This study also documents the dramatic rise in popularity of the French Bulldog, from 0.02% of puppies born in 2003 to 1.46% of puppies born in 2013. This level of population growth in a single dog breed is unprecedented. There is a worry that increased demand for the French Bulldog is damaging to these dogs’ welfare because of the health risks associated with their extreme physical features.”

The authors analyzed data on 2,228 French Bulldogs under veterinary care during 2013 from 304 UK clinics, collected in the VetCompass™ database. The French Bulldogs had a median age of 1.3 years old compared to a median age of 4.5 years for the other dog breeds in the VetCompass™ database. This reflects the growth in popularity of French Bulldogs.

The authors caution that the study may even under-estimate the true number of dogs with health problems as the data may include more severely affected animals that require veterinary management. Additionally, as French Bulldogs have only recently become popular the data was mostly collected from young dogs and it is well recognized that health problems generally become more common with age.

Source:  Science Daily

Read the journal article here

 

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Researchers identify a common underlying genetic basis for social behavior in dogs and humans

Dogs’ ability to communicate and interact with humans is one the most astonishing differences between them and their wild cousins, wolves. A new study published in the journal Science Advances identifies genetic changes that are linked to dogs’ human-directed social behaviors and suggests there is a common underlying genetic basis for hyper-social behavior in both dogs and humans.

An interdisciplinary team of researchers, including those from Princeton University, sequenced a region of chromosome 6 in dogs and found multiple sections of canine DNA that were associated with differences in social behavior. In many cases, unique genetic insertions called transposons on the Williams-Beuren syndrome critical region (WBSCR) were strongly associated with the tendency to seek out humans for physical contact, assistance and information.

In contrast, in humans, it is the deletion of genes from the counterpart of this region on the human genome, rather than insertions, that causes Williams-Beuren syndrome, a congenital disorder characterized by hyper-social traits such as exceptional gregariousness.

“It was the remarkable similarity between the behavioral presentation of Williams-Beuren syndrome and the friendliness of domesticated dogs that suggested to us that there may be similarities in the genetic architecture of the two phenotypes,” said Bridgett vonHoldt, an assistant professor in ecology and evolutionary biology at Princeton and the study’s lead co-author.

Dogs ability to communicate

Dogs’ ability to communicate and interact with humans is one of the most astonishing differences between them and their wild cousins, wolves. Shown here, Lauren Brubaker, a graduate research assistant in the Department of Animal and Rangeland Sciences at Oregon State University and one of the study’s authors, interacts with a gray wolf. Photo by Monty Sloan

VonHoldt had identified the canine analog of the WBSCR in her publication in Nature in 2010. But it was Emily Shuldiner, a 2016 Princeton alumna and the study’s other lead co-author, who, as part of her senior thesis, pinpointed the commonalities in the genetic architecture of Williams-Beuren syndrome and canine tameness.

By analyzing behavioral and genetic data from dogs and gray wolves, vonHoldt, Shuldiner and their colleagues reported a strong genetic aspect to human-directed social behavior by dogs. Monique Udell, an assistant professor of animal and rangeland sciences at Oregon State University and the paper’s senior author, collected and analyzed the behavioral data for 18 domesticated dogs and 10 captive human-socialized wolves, as well as the biological samples used to sequence their genomes.

First, Udell quantified human-directed sociability traits in canines, such as to what extent they turned to a human in the room to seek assistance in trying to lift a puzzle box lid in order to get a sausage treat below or the degree to which they sought out social interactions with familiar and unfamiliar humans. Then, vonHoldt and Shuldiner sequenced the genome in vonHoldt’s lab and correlated their findings.

Consistent with their hypothesis, the researchers confirmed that the domesticated dogs displayed more human-directed behavior and spent more time in proximity to humans than the wolves. The also discovered that some of these transposons on the WBSCR were only found in domestic dogs, and not in wolves at all.

VonHoldt’s findings suggest that only a few transposons on this region likely govern a complex set of social behaviors. “We haven’t found a ‘social gene,’ but rather an important [genetic] component that shapes animal personality and assisted the process of domesticating a wild wolf into a tame dog,” she said.

Anna Kukekova, an assistant professor in the Department of Animal Sciences at the University of Illinois at Urbana-Champaign who is familiar with the research but had no role in it, said that the paper points to these genes as being evolutionarily conserved, or essentially unchanged throughout evolution. “The research provides evidence that there exist certain evolutionary conservative mechanisms that contribute to sociability across species,” she said. “That they have found that this region contributes to sociability in dogs is exciting.”

The researchers’ evidence also calls into question the role of domestication in the evolution of canine behavior. Most experts agree that the first domesticated dogs were wolves that ventured into early human settlements. These proto-dogs evolved not only in their looks, but also their behavior, a process likely influenced by the species’ cohabitation, according to vonHoldt.

However, unlike previous research which suggests that, during the process of domestication, dogs were selected for a set of cognitive abilities, particularly an ability to discern gesture and voice, vonHoldt and Shuldiner’s research posits that dogs were instead selected for their tendency to seek human companionship.

“If early humans came into contact with a wolf that had a personality of being interested in them, and only lived with and bred those ‘primitive dogs,’ they would have exaggerated the trait of being social,” vonHoldt said.

Source:  Princeton University media statement

Canine hereditary diseases more common than previously indicated

Comment from me (DoggyMom):  I am particularly pleased to read in this media release that the researchers are recommending cooperation between industry, science and laypersons.  As a canine massage therapist, I have found the traditional ‘evidence-based medicine’ fraternity reluctant to involve specialists in other fields and particularly those that are not research scientists or veterinarians.
It is my hope that we can cooperate more in the future as we undertake research into dog health and behavior because by sharing different points of view and expertise, we develop a richer range of options in problem-solving.
Kathleen Crisley, specialist in dog massage, rehabilitation and nutrition/food therapy, The Balanced Dog, Christchurch, New Zealand

Genoscoper Ltd. has published in cooperation with the researchers of University of Helsinki and Pennsylvania (USA) the most comprehensive study on canine hereditary disorders so far. The research brings new information about genetic disorders causing diseases in different dog breeds. The results can be utilized both in dog breeding and veterinary diagnostics. The study was published on PLOS ONE on 15 August 2016.
Dogs have more hereditary diseases than previously thought

Dogs have more hereditary diseases than previously thought. Photo: Eeva Karmitsa

– We noted that surprisingly many canine inherited disorders are actually more widespread than indicated by their original discovery studies, which opens up the door for several future scientific investigations, explains senior author Dr. Hannes Lohi from the University of Helsinki canine genetics research group.

– The technological potential to test a dog for multiple inherited disorders at once has existed for several years. The challenge is to harness that potential for practical use in improved veterinary disease diagnostics, sustainable breeding selections, personalized pet care, and canine genetics research, says lead author Dr. Jonas Donner of Genoscoper Laboratories. Genoscoper Ltd. is a Finnish company specialized in animal genetics and gene testing.

By testing nearly 7000 dogs representing around 230 different breeds for predisposition to almost 100 genetic disorders, the research team observed that 1 in 6 dogs carried at least one of the tested disease predisposing genetic variants in their genome. Moreover, 1 in 6 of the tested genetic variants was also discovered in a dog breed in which it had not previously been reported in the scientific literature. Through clinical follow up of dogs genetically at risk, the research team was able to confirm that several disorders cause the same disease signs also in other than previously described breeds.

– Precisely as we humans, every dog is likely to carry genetic predisposition for some inherited disorder, so we expect these numbers to grow as the numbers of tested disease variants, breeds, and dogs further increase, confirms Dr. Donner.

Co­oper­a­tion is key to health­ier dogs

– Our study demonstrates the importance of collaboration between different contributors – academics, industry and dog fanciers – to reach novel resources that not only enable better understanding of canine genetic health across breeds but also provides viable solutions to improve the health.  The published study provides also an excellent example of the added value of research collaborations between academia and industry in a form that leads to a powerful innovation that start changing the everyday practice in veterinary medicine and improves the welfare of our dogs, says Lohi.

Ge­netic panel screen­ing de­liv­ers res­ults

The study concludes that comprehensive screening for canine inherited disorders represents an efficient and powerful diagnostic and research discovery tool that has a range of applications in veterinary care, disease research, and dog breeding. The authors emphasize that availability of complex DNA-based information is important progress for improvement of the health of purebred dogs, but it should be utilized in combination with other established approaches that promote sustainable breeding and benefit breed health.

The full scientific publication can be accessed here.

Reference:
Donner J, Kaukonen M, Anderson H, Möller F, Kyöstilä K, Sankari S, Hytönen MK, Giger U and Lohi H. Genetic panel screening of nearly 100 mutations reveals new insights into the breed distribution of risk variants for canine hereditary disorders. PlosONE, 1(8): e0161005. doi:10.1371/journal.pone.0161005, 2016.

Source:  University of Helsinki media release

Domestication Syndrome

More than 140 years ago, Charles Darwin noticed something peculiar about domesticated mammals. Compared to their wild ancestors, domestic species are more tame, and they also tend to display a suite of other characteristic features, including floppier ears, patches of white fur, and more juvenile faces with smaller jaws. Since Darwin’s observations, the explanation for this pattern has proved elusive, but now, in a Perspectives article published in the journal GENETICS, a new hypothesis has been proposed that could explain why breeding for tameness causes changes in such diverse traits.

Photo courtesy of Lucky Dog Animal Rescue

Helios, an approximately 3-year-old cattle dog/greyhound mix with Lucky Dog Animal Rescue. Photo courtesy Lucky Dog Animal Rescue

The underlying link between these features could be the group of embryonic stem cells called the neural crest, suggests the research team.

“Because Darwin made his observations just as the science of genetics was beginning, the domestication syndrome is one of the oldest problems in the field. So it was tremendously exciting when we realized that the neural crest hypothesis neatly ties together this hodge-podge of traits,” says Adam Wilkins, from the Humboldt University of Berlin – one of the study’s authors.

Neural crest cells are formed near the developing spinal cord of early vertebrate embryos. As the embryo matures, the cells migrate to different parts of the body and give rise to many tissue types. These tissues include pigment cells and parts of the skull, jaws, teeth, and ears—as well as the adrenal glands, which are the center of the “fight-or-flight” response. Neural crest cells also indirectly affect brain development.

In the hypothesis proposed by Wilkins and co-authors Richard Wrangham of Harvard University and Tecumseh Fitch of the University of Vienna, domesticated mammals may show impaired development or migration of neural crest cells compared to their wild ancestors.

“When humans bred these animals for tameness, they may have inadvertently selected those with mild neural crest deficits, resulting in smaller or slow-maturing adrenal glands,” Wilkins says. “So, these animals were less fearful.”

The authors also suggest that the reduced forebrain size of most domestic mammals could be an indirect effect of neural crest changes, because a chemical signal sent by these cells is critical for proper brain development.

The hypothesis will require testing, which will be able to be done once genetic mapping of domesticated species like the dog, fox and rat are completed.

Full journal article details:  The “Domestication Syndrome” in Mammals: A Unified Explanation Based on Neural Crest Cell Behavior and Genetics
Adam S. Wilkins, Richard W. Wrangham, and W. Tecumseh Fitch. GENETICS July 2014, 197:795-808, doi: 10.1534/genetics.114.165423
http://www.genetics.org/content/197/3/795.full

Source:  Genetics Society of America media release

 

The ancestral roots of your dog

A genetic study by Peter Savolainen, a researcher in evolutionary genetics at KTH Royal Institute of Technology in Stockholm, has found that dog breeds from North and South America have Asian ancestry.

The Chihuahua definitely has Mexican heritage

The Chihuahua definitely has Mexican heritage

The native breeds have 30 percent or less modern replacement by European dogs.  It had been thought, prior to this study, that when Europeans settled in the American continent their dog breeds successively replaced the genetics of the native breeds.

Savolainen’s research group, in cooperation with colleagues in Portugal, compared mitochondrial DNA from Asian and European dogs, ancient American archaeological samples, and American dog breeds, including Chihuahuas, Peruvian hairless dogs and Arctic sled dogs.

They traced the American dogs’ ancestry back to East Asian and Siberian dogs, and also found direct relations between ancient American dogs and modern breeds.

The research confirmed conclusively that the modern day Chihuahua has Mexican roots.  The breed shares a DNA type uniquely with Mexican pre-Columbian samples.

The team also analysed stray dogs, confirming them generally to be runaway European dogs; but in Mexico and Bolivia they identified populations with high proportions of indigenous ancestry.

Source:  AlphaGalileo Foundation news release

Getting your head around dog genetics

Another public release of research this week.  This one from the Genetics Society of America about an article entitled ‘The Genetics of Canine Skull Shape Variation.’  Published in the February issue of Genetics, researchers review progress in defining genes and pathways that determine dog skull shape and development.

The researchers believe that the results are useful to humans because of the genetic expression of the features is likely to be similar process in humans as in dogs.

Skull shape is a complex trait, involving multiple genes and their interactions. Thanks to standardized canine breeding, which documents more than 400 breeds worldwide, and their distinct morphological features, researchers can disentangle traits such as skull shape, which in many breeds is a breed-defining variation.

Researchers are beginning to identify which genes cause a Bulldog or a Pug to have short pushed-in faces, or brachycephaly, and those that cause Salukis or collies to have narrow, elongated snouts, or dolichocephaly.

Source:  Genetics Society of America media release

Re-thinking dog domestication

A research team led by the University of Durham has published a study in the Proceedings of the National Academy of Sciences (USA).  This study shows that today’s modern breeds of dog have little in common genetically with their ancient ancestors. 

Dog domestication occurred over 15,000 years ago – and there is still much to learn!

Years of cross-breeding are the major influence on the genetic differences, although the researchers are quick to add that other effects on genetic diversity will include patterns of human movement and the impact on dog population sizes caused by major events such as World War I and World War II.

The research team analysed genetic data from 1,375 dogs representing 35 breeds. They also looked at data showing genetic samples of wolves because other research studies have concluded that the dog descended directly from the gray wolf.

Lead author Dr Greger Larson, an evolutionary biologist, says the study demonstrated just how much there is still to understand about the early history of dog domestication.  “We really love our dogs and they have accompanied us across every continent.  Ironically, the ubiquity of dogs combined with their deep history has obscured their origins and made it difficult for us to know how dogs became man’s best friend.”

The study also refutes claims of previous researchers that genetic differences in breeds such as the Basenji, Saluki and Dingo were evidence of an ancient heritage.  The Durham team’s study shows that these dogs are genetically different because they were geographically isolated and were not part of the 19th Century Victorian-initiated kennel clubs that blended lineages to create most of today’s breeds.

A Saluki (copyright Keith Dobney)

Source:  University of Durham press release