Category Archives: research

Our ability to read dogs’ facial expressions is learned, not innate

In a recent study published in Scientific Reports, a team of researchers from Germany and the United Kingdom assessed how experience with dogs affects humans’ ability to recognize dog emotions. Participants who grew up in a cultural context with a dog-friendly attitude were more proficient at recognizing dog emotions. This suggests that the ability to recognize dogs’ expressions is learned through age and experience and is not an evolutionary adaptation.

Facial expressions study

The study used photos of dogs with wolf-like faces and upright ears for emotion recognition © Juliane Bräuer

Dogs were the first domesticated animal, with humans and dogs sharing more than 40,000 years of social interactions and life together. According to the co-domestication hypothesis, this process allowed humans and dogs to evolve special emotional signals and cognitive skills that favor mutual understanding. We know, for example, that over the millennia, dogs have evolved the ability to understand human words, iconic signs, and other gestures, and research has shown that dogs can even use tone of voice and facial expressions to recognize human emotions. Beyond personal testimony from dog lovers, however, little attention has been paid to how well humans can understand their canine counterparts.

In the current study, led by Federica Amici of the Max Planck Institute for Evolutionary Anthropology and Juliane Bräuer of the Max Planck Institute for the Science of Human History, the researchers set out to understand how well humans can understand the emotional displays of dogs, and where that understanding comes from.

How well do we understand our species’ best friend?

In order to test how well humans can understand the emotions behind dog facial expressions, researchers collected photographs of dogs, chimpanzees, and humans displaying either happy, sad, angry, neutral, or fearful emotions as substantiated by the photographers. They then recruited 89 adult participants and 77 child participants and categorized them according to their age, the dog-positivity of their cultural context, and the participants’ personal history of dog ownership.

Each participant was presented with photographs of dogs, chimps, and humans, and asked to rate how much the individual in the picture displayed happiness, sadness, anger, or fear. Adults were also asked to determine the context in which the picture had been taken (e.g., playing with a trusted conspecific partner; directly before attacking a conspecific). The results of the study showed that, while some dog emotions can be recognized from early on, the ability to reliably recognize dog emotions is mainly acquired through age and experience. In adults, the probability of recognizing dog emotions was higher for participants who grew up in a cultural context with a positive attitude towards dogs, regardless of whether they owned a dog themselves.

Without a dog-positive context, we could be barking up the wrong tree

A dog-postive cultural background, one in which dogs are closely integrated into human life and considered highly important, may result in a higher level of passive exposure and increased inclination and interest in dogs, making humans better at recognizing dogs’ emotions even without a history of personal dog ownership. “These results are noteworthy,” says Amici, “because they suggest that it is not necessarily direct experience with dogs that affects humans’ ability to recognize their emotions, but rather the cultural milieu in which humans develop.”

The researchers also found that regardless of age or experience with dogs, all participants were able to identify anger and happiness reliably. While these results may suggest an innate ability favored by the co-domestication hypothesis, it is also possible that humans learn to recognize these emotions quickly, even with limited exposure. Other than anger and happiness, the children in the study were not good at identifying dog emotions. They recognized anger and happiness more reliably in dogs than in chimps, but otherwise identified dog emotions as poorly as they did chimpanzee emotions, suggesting that the ability to understand how dogs are feeling is not innate.

“We think it would be valuable to conduct future studies that seek to determine exactly which cultural aspects affect one’s ability to read dog emotions, and to include real-life stimuli and body expressions in addition to instructed stimuli and facial expressions,” states Bräuer. “In this way, we could develop a better understanding of inter-cultural variation in emotion recognition. Hopefully this information could be used to reduce the occurrence of negative incidents between humans and dogs that are caused by humans’ inability to read dog signals.”

Source:  Max Planck Institute for the Science of Human History

 

Your dog might be hiding its true colors

If you have a purebred dog, it’s likely that he or she looks fairly similar to other dogs of the same breed, especially when it comes to the color of their coats.

But what happens if a purebred puppy doesn’t look exactly like its siblings when it’s born? Chances are, it might not be a flaw – but rather a hidden gene variant that decided to show itself.

New research from Purdue University’s College of Veterinary Medicine shows that some breeds of dogs have hidden coat colors – and in some cases, other traits – that have been lurking all along.

Purdue university research into coat color

New research from Purdue University’s College of Veterinary Medicine shows that some breeds of dogs have hidden coat colors – and in some cases, other traits – that have been lurking all along. Example: There are around 18 recognized breeds of dogs that have the genetic potential to be born without a tail – such as the popular Australian Shepherd (shown in photo). But the data shows that up to 48 of the breeds analyzed possess the tailless gene variant, usually at a very low frequency.

Led by Kari Ekenstedt, DVM, Ph.D., assistant professor of anatomy and genetics, and Dayna Dreger, Ph.D., the lead scientist in Ekenstedt’s canine genetics research laboratory, the team looked at a dozen different genes in 212 dog breeds. Purdue researchers, together with industry partners at Wisdom Health, analyzed data that had been initially collected by WISDOM PANEL™ for the development of canine DNA tests. The work was published Oct. 28 in PLOS ONE.

“These are purebred dogs with traits that their breed clubs say they’re not supposed to have,” said Ekenstedt, whose research program focuses on canine genetics. “The message of this paper is, ‘Hey, these gene variants exist in your breed, and if a few dogs are born with these traits, it’s not caused by accidental breeding and it’s not a mutt; it’s a purebred showing this known genetic potential.’”

Along with analyzing the data, researchers used standard breed descriptions from major American and international dog breed registries to determine coat colors and tail lengths that were accepted within each breed.

“There was a lot of information we didn’t expect,” Dreger said. “When it comes to different dog breeds, their standards are mostly based on preference and aesthetics. We make assumptions for certain breeds based on what we expect their coat colors to be.”

Ekenstedt says coat color genes have a significant amount of epistasis between them, meaning that what happens at one gene can mask what’s happening at another gene. Because of epistasis, it’s rare to see those masked genes actually expressed in a dog’s coat color.

One example of a “fault” allele – a gene variant that would cause a trait that is not allowed in a breed standard – is an allele that causes the brown color, which affects both hair pigment and skin pigment. The color is allowed in breeds like the Labrador Retriever where it causes the chocolate color. However, researchers observed that in breeds where brown is not allowed, such as the Rottweiler and the German Shepherd Dog, brown alleles exist at low frequencies.

Another example of a fault allele is in the Weimaraner, which exists in both longhaired and shorthaired varieties. At least one dog breed organization does not allow longhaired Weimaraners while several others do allow them.  Of the Weimaraners sampled in this data, the longhaired allele is present at a 4% frequency.

The same goes for other traits, too, Dreger said. For example, there are around 18 recognized breeds of dogs that have the genetic potential to be born without a tail – such as the popular Australian Shepherd. But the data shows that up to 48 of the breeds analyzed possess the tailless gene variant, usually at a very low frequency; one of those breeds is the Dachshund.

“A breeder would certainly be surprised to see a Dachshund born without a tail,” Dreger said. “The chances are low, but our research shows that the potential is there.”

Both Dreger and Ekenstedt hope the research prompts some discussions within the dog community.

“I want this to start science-based conversations,” Dreger said. “We’re not here to make decisions on what a breed should or shouldn’t look like or what a breed club should do. We’re here to say these are the facts, and these are the gene variants that naturally exist in these breeds.”

They also hope it changes some perspectives when it comes to what is to be expected with certain breeds of dogs.

“There’s an assumption that the standards for these different breeds of dogs are set in stone,” Dreger said. “People will often make assumptions that if it doesn’t match this, it’s not purebred. This data shows that there is a lot of variation in some of these breeds, and the standards are not as concrete as we expect them to be.”

Wisdom Health funded a Veterinary Summer Scholar position to Blair Hooser, a student at the Purdue College of Veterinary Medicine and coauthor on the paper, for this work. Partial support for Dr. Ekenstedt was provided by the National Institutes of Health.

Source:  Purdue University media release

Estrogen’s opposing effects on mammary tumors in dogs

Dogs that are spayed at a young age have a reduced risk of developing mammary tumors, the canine equivalent of breast cancer. Early spaying reduces levels of estrogen production, leading many veterinarians and scientists to cast estrogen in a negative light when it comes to mammary cancer.

But the effects of estrogen on cancer risk in dogs aren’t straightforward, according to a new study led by researchers from Penn’s School of Veterinary Medicine. While it’s clear that spaying dogs greatly minimizes their risk of developing mammary cancer, the findings suggest that the practice may increase the risk of more aggressive cancers. And in spayed animals with mammary tumors, the team found that higher serum estrogen levels were actually protective, associated with longer times to metastasis and improved survival times.

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Veterinary oncologist Karin Sorenmo and colleagues cast new light on the complex role of estrogen in canine mammary cancer. The research emerged from Penn Vet’s Shelter Canine Mammary Tumor Program, which assists in treating and then finding homes for dogs like Brownie, pictured with former oncology intern, Kiley Daube.

“Dogs that remain intact and have their ovaries develop many more mammary tumors than dogs that were spayed, so removing that source of estrogen does have a protective effect,” says Karin U. Sorenmo, a veterinary oncologist at Penn Vet and senior author on the study, published in PLOS ONE. “Estrogen does seem to drive mammary cancer development. But what it does for progression to metastasis—that I think is more complicated.”

Sorenmo and colleagues have been studying mammary tumors in dogs as a way of improving care and treatment for pets but also to make insights into human breast cancer biology.

“Much of the research we do in veterinary medicine looks at what is done in people and then adapts it,” she says. “But dogs are such a great, comprehensive model for cancer. Yes, there are differences in biology between dogs and people, but here those differences may allow us to ask very probing questions about what estrogen is doing in both dogs with mammary cancer and women with breast cancer.”

The research used data from two prospective studies, including one involving dogs in the Penn Vet Shelter Canine Mammary Tumor Program, through which shelter dogs with mammary tumors receive treatment, are studied by researchers like Sorenmo, and then find foster or permanent homes.

The team evaluated 159 dogs with mammary cancer, 130 that were spayed as part of the study and 29 that remain intact. In addition to surgically removing the dogs’ measurable tumors, the team collected information on serum estrogen levels, tumor type, disease grade and stage, time to metastasis, and survival time.

Despite estrogen’s link with an increased risk of developing mammary tumors, the researchers found that higher serum estrogen levels also seemed to help dogs avoid some of the riskiest aspects of their disease. Unexpectedly, when dogs were spayed at the same time their tumors were removed, those with estrogen receptor-positive tumors that had higher serum estrogen took longer to develop metastatic disease and survived longer than dogs with lower estrogen levels, confirming that these tumors depended on estrogen for progression.

Sorenmo speculates that, in these cases, estrogen’s action may be nuanced. “It drives the cancer, but it also seems to control or modulate it, reining it in,” she says, because most dogs with high serum estrogen levels had lower-grade and estrogen receptor-positive tumors, rendering them susceptible to hormonal deprivation by spaying.

The protective role of estrogen was also surprisingly pronounced in dogs with estrogen-receptor negative mammary tumors. In these higher-risk cancers, high serum estrogen was associated with delayed or absent metastasis. Complementing these findings and supporting a potential broader, tumor receptor-independent anti-cancer effect driven by estrogen, dogs with low serum estrogen had a significantly increased risk for developing other non-mammary aggressive fatal tumors, such as hemangiosarcoma, during their follow-up after mammary tumor surgery.

Some of the findings contradict what has been found in women with breast cancer. For example, higher serum estrogen levels in women following breast cancer therapy have been associated with higher rates of recurrence. But Sorenmo also notes that many cases of breast cancer in women arise just after menopause, when estrogen levels tumble. So there may be a more complex role for estrogen in people’s cancer risk as well.

The work points to new possibilities for examining the role of estrogen in cancer initiation and progression. Already, Sorenmo and colleagues, including Penn Vet’s Susan Volk and Ellen Puré, are pursuing investigations of how the hormone affects the tumor microenvironment, cells that aren’t themselves cancerous but may either stem or encourage a tumor’s growth and spread.

“I think this study opens some really complicated questions,” Sorenmo says. “If we start dissecting exactly what estrogen is doing, what genes or immune cells it’s interacting with, maybe we could harness the power of estrogen to be more clever in our treatment strategies.”

Source:  Penn Today

Overweight Danes are more likely to have overweight dogs according to new research

A new study from the University of Copenhagen reports that the prevalence of overweight dogs is markedly larger among overweight owners than among normal weight owners. Part of the explanation lies in whether treats are used as training tools or “hygge-snacks”. It is the first major study on canine obesity in Denmark.

Cute fat pug dog with funny face

Getty images

There’s a bit of truth to the saying “like owner, like dog”. This has now been confirmed by researchers. For the first time in Denmark, researchers have systematically investigated the factors related to our four-legged friends being overweight or obese.  One of the results demonstrates an unambiguous correlation between the weight status of a dog and its owner.

The study, conducted by researchers at the University of Copenhagen, shows that the prevalence of heavy or obese dogs is more than twice as large among overweight or obese owners than among owners who are slim or of a normal weight.

Part of the explanation rests upon how owners manage dog treats. The research results show a correlation between overweight dog owners and the use of dog treats as “hygge-candy” (cozy-candy).

“Whereas normal weight owners tend to use treats for training purposes, overweight owners prefer to provide treats for the sake of hygge. For example, when a person is relaxing on the couch and shares the last bites of a sandwich or a cookie with their dog,” says Charlotte R. Bjørnvad of the University of Copenhagen’s Department of Veterinary Clinical Sciences. Bjørnvad, a veterinarian and professor, is the main author of the research article, now published in the journal Preventive Veterinary Medicine.

The researchers studied 268 adult dogs recruited at animal clinics around Zealand and the Capital Region of Denmark. Of the pets recruited, 20% were either heavy or obese.

“Oftentimes, people don’t consider their dog’s weight status to be a problem. And this might contribute to a dog’s being overweight. But being heavy or obese does have a great impact on dog health – which on average results in a shortened lifespan”, according to bioethics professor and article co-author, Peter Sandøe, of the University of Copenhagen’s Department of Food and Resource Economics.

Previous studies have shown that on average, heavy dogs live 1.3 years less than dogs on restrictive diets and that part of the explanation may be an earlier development of osteoarthritis with the heavier weight.

Castration triples the risk of being heavy or obese

The researchers also looked into how castration and sterilization can be risk factors in relation to dog weight. The study shows that castrated male dogs have three times as high a risk of being heavy or obese compared to intact dogs. On the other hand, the study demonstrated that sterilization has no impact on weight in female dogs.  Whether they are intact or not, female dogs, have an increased risk of being heavy compared with intact males.

“When males are castrated, they face just as high of a risk of becoming overweight as females. Castration seems to decrease the ability to regulate the appetite in male dogs and at the same time, it might also decrease the incentive to exercise which results in an increased risk of becoming overweight. Therefore, an owner should be careful about how they feed their dog after it has been castrated,” says Bjørnvad.

Sandøe adds: “They might even want to consider not neutering. As long as there are no runaway females in the area, there are in most cases no reason to neuter.”

The researchers hope that this new knowledge raises awareness about canine weight among veterinarians and dog owners, and that it contributes to better obesity prevention and treatment strategies by identifying focus areas for intervention.

Source:  University of Copenhagen media release

Dachshund gait research has broader implications for rehab medicine

The trademark wiggle of a dachshund’s stride could point to more than just life with little legs.

Over the summer, a team at the Western College of Veterinary Medicine set out to characterize what the breed’s normal gait looks like in order to better detect abnormalities like back injuries.

Dachshund

Veterinary student Rachel McCann takes Juniper down a pressure walkway. The research project focused on how dachshunds walk and found they put more weight on their front limbs than other breeds. Liam Richards / Saskatoon StarPhoenix

Supervised by Drs. Romany Pinto, Danielle Zwueste and Kira Penney, veterinary student Rachel McCann trotted 30 dachshunds through the Veterinary Medical Centre’s canine rehabilitation centre and looked at how they moved.

Ultimately, the findings will go toward a second project looking at rehabilitating dogs of various breeds with spinal injuries. Because it’s expected that many of the subjects involved in that project will be dachshunds, it made sense to establish a norm to work from, McCann said.

The research, already completed on a handful of breeds like labradors and beagles, is the first to focus on dachshunds.

“There hasn’t been any papers published on them and what the normal parameters for them are,” she said. “They’re a breed that suffers from intervertebral disc disease, and that comes in so often for rehab medicine. So it would be really useful to the veterinary community to know what’s normal in them.”

The subjects, volunteered by owners in Saskatoon, walked across a computerized pressure walkway connected to an interface that measured various aspects of their gait, like pressure distribution and length of stride.

“One thing that we focused on, because we found it was different in dachshunds from other breeds that have been studied before, is how much weight they place in their front limbs compared to their hind limbs,” McCann said.

The project found that dachshunds have a higher thoracic to pelvic force ratio than other breeds, meaning they put more weight on their front limbs.

McCann said she was initially drawn to the field of veterinary rehabilitation while working with her own dog when she suffered from a torn ligament.

“I brought her in for the treatments and it was really a fun time. They gave me a treatment plan where I had to go home and work with her on rehabilitating her,” she said.

“What I like about veterinary rehabilitation is that it really harbours the human-animal bond. This summer has been one of the best experiences of my life.”

Source: Saskatoon Star Phoenix, 25 September 2019

The diet-microbiome connection in inflammatory bowel disease

Much remains mysterious about the factors influencing human inflammatory bowel disease (IBD), but one aspect that has emerged as a key contributor is the gut microbiome, the collection of microorganisms dwelling in the intestines.

Diet is known to profoundly affect this microbial community, and special diets have been used as therapies for intestinal disorders including Crohn’s disease in people. They’re also commonly used in dogs, which can develop a chronic intestinal disease that mirrors many features of Crohn’s.

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Tracking dogs on a prescription diet for an intestinal disease, researchers found that those that responded well shared a suite of changes to their microbiome. (Image: Penn Vet)

In a new study published in the journal Microbiome, researchers from the University of Pennsylvania investigated the connection between a prescription diet, the gut microbiome, and a successful entry into disease remission in pet dogs receiving treatment at Penn Vet’s Ryan Veterinary Hospital. They discovered key features of the microbiome and associated metabolic products that appeared only in dogs that entered disease remission. A type of bacteria that produces these compounds, known as secondary bile acids, alleviated disease in a mouse model. And comparing the impact of diet on the dog’s microbiome with that seen during diet therapy in children with Crohn’s, the study team found notable similarities.

“The bacteria in the gut are known to be a really important factor in tipping the scales toward disease,” says Daniel Beiting, senior author on the work and an assistant professor in the School of Veterinary Medicine. “And the environmental factor that seems to contribute the most to rapid changes in the microbiome is what you eat. Given that dogs’ microbiomes are extremely similar to those of humans, we thought this was an intriguing model to ask, ‘Could diet be impacting this disease through an impact on the microbiome?’”

To begin pursuing this question required treating a population of pet dogs with canine chronic enteropathy (CE), a chronic condition involving weight loss and gut inflammation, diarrhea, occasional vomiting, loss of appetite, and a chronic relapsing and remitting, just as seen in Crohn’s disease. The study involved 53 dogs, 29 with CE being treated at Penn Vet’s Ryan Veterinary Hospital, and 24 healthy controls.

Researchers collected stool samples at the outset of the study and at different times as the sick dogs began a prescription diet to treat their disease. Using advanced genetic sequencing techniques, the team developed a catalog of the microbes present in the stool, a stand-in for the animals’ gut microbiome. They also collected information about the metabolic products present in the stool.

“That gives us a functional read-out of the microbiome,” says Beiting. “It doesn’t just tell us who is there but also what they’re doing.”

Twenty of the 29 sick dogs quickly entered remission. Together, the genomic and metabolite analyses revealed characteristic changes in these dogs. In particular, those that responded well to the diet tended to have an increase in metabolites known as secondary bile acids. These are produced when certain microbes in the gut consume the bile that is released by the liver.

One of these “good” microbes that can give rise to secondary bile acids was the bacterium Clostridium hiranonis, which the researchers found in greater numbers in dogs that went into remission. Dogs that responded well to the diet also had fewer harmful bacteria, such as Escherichia coli and Clostridium perfringens after starting treatment.

To learn more about what these apparent markers of remission were doing, the team took bacteria from the dogs—both when they were sick and after they had entered remission—and grew them in the lab.

“Having these organisms gave us the opportunity to test our hypothesis about what actually causes remission,” says Shuai Wang, a postdoc at Penn Vet and the study’s lead author.

Taking the secondary bile acids found to be associated with remission, the researchers applied them to the E. coli and C. perfringens grown from the sick dogs and found the bile acids inhibited their growth. They also gave C. hiranonis from the dogs to mice with a form of inflammatory bowel disorder to see if the bacteria could reduce disease in a different animal model.

“We observed a stabilization of secondary bile acid levels and reduced inflammation,” Wang says.

“This allowed us to show that secondary bile acids and C. hiranonis aren’t just biomarkers of remission,” says Beiting, “they can actually effect change. Bile acids can block the growth of pathogens, and C. hiranonis can improve gut health in mice.”

As a final step, the researchers looked to a dataset taken from children with Crohn’s disease who were treated with a specialized liquid diet known as exclusive enteral nutrition. Youngsters who responded to the therapy had an increase in numbers of the bacteria species Clostridium scindens, which, like C. hiranonis, is a potent producer of secondary bile acids.

The authors say the findings offer hope for better dietary therapies for IBD, perhaps ones that deliver “good” bacteria such as C. scindens or C. hiranonis while suppressing disease-associated species.

“Similar environmental exposures of dogs and children make the canine IBD model an excellent model of pediatric inflammatory bowel disease,” says Robert N. Baldassano, a study coauthor and pediatric gastroenterologist at Children’s Hospital of Philadelphia. “This study has greatly improved our knowledge of pediatric IBD and will lead to new therapies for children suffering with this disease.”

Source:  Penn Today

How Humans Have Shaped Dogs’ Brains

Dog brain structure varies across breeds and is correlated with specific behaviors, according to new research published in JNeurosci. These findings show how, by selectively breeding for certain behaviors, humans have shaped the brains of their best friends.

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Over several hundred years, humans have selectively bred dogs to express specific physical and behavioral characteristics. Erin Hecht and colleagues investigated the effects of this selective pressure on brain structure by analyzing magnetic resonance imaging scans of 33 dog breeds. The research team observed wide variation in brain structure that was not simply related to body size or head shape.

The team then examined the areas of the brain with the most variation across breeds. This generated maps of six brain networks, with proposed functions varying from social bonding to movement, that were each associated with at least one behavioral characteristic. The variation in behaviors across breeds was correlated with anatomical variation in the six brain networks.

Studying the neuroanatomical variation in dogs offers a unique opportunity to study the evolutionary relationship between brain structure and behavior.

Read the manuscript in JNeurosci: Significant Neuroanatomical Variation Among Domestic Dog Breeds

Source:  Society for Neuroscience