Tag Archives: microbiome

Dogs could be more similar to humans than we thought

Dog and human gut microbiomes have more similar genes and responses to diet than we previously thought, according to a study published in the open access journal, Microbiome.

Canine Microbiome

The canine microbiome is quite similar to that of humans. Credit: © Kar Tr / Fotolia

Dr Luis Pedro Coelho and colleagues from the European Molecular Biology Laboratory, in collaboration with Nestlé Research, evaluated the gut microbiome of two dog breeds and found that the gene content of the dogs microbiome showed many similarities to the human gut microbiome, and was more similar to humans than the microbiome of pigs or mice.

Dr Luis Pedro Coelho, corresponding author of the study, commented: “We found many similarities between the gene content of the human and dog gut microbiomes. The results of this comparison suggest that we are more similar to man’s best friend than we originally thought.”

The researchers found that changes in the amount of protein and carbohydrates in the diet had a similar effect on the microbiota of dogs and humans, independent of the dog’s breed or sex. The microbiomes of overweight or obese dogs were found to be more responsive to a high protein diet compared to microbiomes of lean dogs; this is consistent with the idea that healthy microbiomes are more resilient.

Dr Luis Pedro Coelho, commented: “These findings suggest that dogs could be a better model for nutrition studies than pigs or mice and we could potentially use data from dogs to study the impact of diet on gut microbiota in humans, and humans could be a good model to study the nutrition of dogs.

“Many people who have pets consider them as part of the family and like humans, dogs have a growing obesity problem. Therefore, it is important to study the implications of different diets.”

The researchers investigated how diet interacted with the dog gut microbiome with a randomized controlled trial using a sample of 64 dogs, half of which were beagles and half were retrievers, with equal numbers of lean and overweight dogs. The dogs were all fed the same base diet of commercially available dog food for four weeks then they were randomized into two groups; one group consumed a high protein, low carb diet and the other group consumed a high carb, low protein diet for four weeks. A total of 129 dog stool samples were collected at four and eight weeks. The researchers then extracted DNA from these samples to create the dog gut microbiome gene catalogue containing 1,247,405 genes. The dog gut gene catalogue was compared to existing gut microbiome gene catalogues from humans, mice and pigs to assess the similarities in gene content and how the gut microbiome responds to changes in diet.

The authors caution that while humans and dogs host very similar microbes, they are not exactly the same microbes, but very closely related strains of the same species.

Source:  Science Daily

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Study Shows How a Dog’s Diet Shapes Its Gut Microbiome

Studies of the gut microbiome have gone to the dogs — and pets around the world could benefit as a result.

In a  paper published in the journal mBio, researchers from Nestle Purina PetCare Company report that the ratio of proteins and carbohydrates in a canine’s daily diet have a significant influence on the balance of microbes in its gut. Among other findings, they observed that dogs fed a high-protein, low-carbohydrate diet had decreases in the ratio of Bacteroidetes to Firmicutes bacteria, as well as enriched microbial gene networks associated with weight loss in humans. The microbial responses were more pronounced in obese and overweight dogs than in dogs of a healthy weight.

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The researchers say their study may help identify new microbiology-inspired strategies for managing pet obesity, which is  a growing problem. More than half of pet dogs in the United States are overweight or obese, according to the most recent annual survey by the Association for Pet Obesity Prevention. A comparison of that data with previous surveys suggests that obesity in dogs, as in people, is getting worse.

“We do believe dogs have become heavier over the last decade, and that it’s an epidemic,” says Johnny Li, a computational biologist at Nestle Purina, in St. Louis, Missouri, who led the new study. Li says he launched the study because only a handful of previous studies have explored the gut microbiome of canines, and the effect of diet on gut microbes hasn’t been well documented.

Studies on animals are lacking, but human studies have connected microbial imbalance in the gut to a variety of conditions, including obesity, metabolic syndrome, cardiovascular disease, immune disorders, and liver and brain diseases.

Li and his team studied 32 Labrador Retrievers and 32 Beagles, with equal numbers of lean and overweight or obese dogs. During the first four weeks, all the dogs were fed the same baseline diet. During the second four weeks, half the dogs received a high-protein, low-carbohydrate diet; the other half received a high-carbohydrate, low-protein diet.

Fecal microbiome studies conducted after the first four weeks revealed few differences in the gut microbiomes of the dogs. Studies conducted after the second four weeks, after the dogs had eaten an experimental diet, showed dramatic changes in the microbiome. Dogs that ate a low-protein, high-carbohydrate diet had higher abundances of Bacteroides uniformis and Clostridium butyricum.

In dogs that ate a high-protein, low-carbohydrate diet, the researchers observed a decrease in the ratio of Bacteroidetes to Firmicutes bacteria. They also reported that abundances of Clostridium hiranonis, Clostridium perfringens, and Ruminococcus gnavus were more than double the abundances observed in the other experimental group.

Li says the effects of diet on the microbiome were more pronounced in obese and overweight dogs than in lean dogs. “That seems to suggest that obese dogs and overweight dogs are more susceptible to dietary intervention,” he says. A different diet for those animals may have a greater impact on the bacterial balance in their guts.

The study involved only two breeds, but Li says the findings are likely applicable to all dog breeds, “though we need more studies on other breeds in the future to be sure.”

Li says his team’s study provides a framework to explore the connection between diet and gut microbes in dogs. Although the findings are preliminary, he says he hopes to see the research eventually translate into real-world ways to modify pet food, perhaps through the strategic use of probiotics or prebiotics, and reduce the obesity epidemic.

View the paper Effects of the Dietary Protein and Carbohydrate Ratio on Gut Microbiomes in Dogs of Different Body Conditions

Source:  American Society of Microbiology press release

 

Changes in Skin “Microbiome” During Canine Atopic Dermatitis Could Lead to Antibiotic-Free Therapies

Atopic dermatitis (AD), a chronic inflammatory skin condition and the most common form of eczema, is estimated to afflict as much as 10 percent of the U.S. population, and is much more common now than it was 50 years ago. Veterinary clinical estimates also show that approximately 10 percent of dogs have atopic dermatitis.

How AD arises isn’t yet fully understood, but a study from researchers from the Perelman School of Medicine at the University of Pennsylvania and Penn’s School of Veterinary Medicine, have uncovered important insights about the association of AD in dogs compared to humans. The study appears online in the Journal of Investigative Dermatology.

atopy

To a greater extent than mouse models, canine AD shares important features of the human version. For example, in both humans and dogs AD has been linked to abnormal blooms of Staphyloccocus bacteria on the skin – mostly Staphyloccocus aureus in humans, and Staphyloccocus pseudintermedius in dogs.

In the study, the research team, comprised of veterinary dermatologists, microbiologists, pathologists, and primary scientists, tracked the bacterial populations, or “microbiomes,” on dogs’ skin, and key properties of the skin’s barrier function during an occurrence of AD, and again after standard treatment with antibiotics. During the flare, researchers observed a sharp decrease in the diversity of the skin bacterial population as certain bacterial species proliferated, along with a decrease in the skin’s protective barrier. With antibiotic therapy, both measures returned to normal levels.

“In both canine and human atopic dermatitis we hypothesize there is a similar relationship among skin barrier function, the immune system, and microbes, even if the individual microbe species aren’t identical,” said senior author Elizabeth A. Grice, PhD, an assistant professor of Dermatology and Microbiology at the Perelman School of Medicine at the University of Pennsylvania. “The hope is that insights gained from this study and others like it will enable us one day to treat this condition by altering the skin’s microbiome without antibiotics.”

Thirty-two dogs (15 with canine AD, and 17 without) from Penn Vet’s Ryan Hospital were enrolled in the study. On three occasions – first during AD flares in the affected dogs, then after 4-6 weeks of targeted antibiotics, and finally 4-6 weeks after treatment concluded – the team took swabs from several areas of skin on the affected dogs. They surveyed the microbiomes of these samples by amplifying and sequencing copies of a key bacterial gene whose DNA sequence is distinct for different bacterial species.

Samples from the dogs with ongoing AD had almost ten times the proportion of Staphylococcus species, compared to the control dogs. Corynebacterium species also rose, as they typically do in humans with AD. A standard measure of the diversity of the dogs’ skin microbiomes also decreased sharply, indicating that the abnormal bacterial proliferation – chiefly from S. pseudintermedius – had crowded out other, harmless or potentially beneficial bacterial species.

At the second visit, immediately following completion of antibiotic therapy, the abundance of Staphyloccocus and Corynebacterium on the skin of affected dogs and the diversity of their skin microbiome had returned almost to the levels seen in the control dogs. Those measures remained largely the same in the third visit, after antibiotic therapy was finished.

Impairment in the skin’s ability to work as a “barrier” to keep moisture in and harmful bacteria out is considered a possible factor in triggering or advancing AD. Under the guidance of Elizabeth Mauldin, DVM DACVP, DACVD, an associate professor of Dermatopathology in Penn’s School of Veterinary Medicine, the researchers also tested skin barrier function in the dogs at each of their three visits. Results showed that the low-bacterial-diversity state of AD flares – corresponding to lesions of AD on the skin – correlated with impairments in the skin barrier, as indicated by a standard test of the water loss rate through the skin (TEWL).

“We don’t know if the bacterial overgrowth is weakening the skin’s barrier function or a weakening of the barrier is enabling the bacterial overgrowth, but we do know now that they’re correlated, and that’s a novel finding,” Grice said.

The research team is now conducting further studies of the microbiome in canine atopic dermatitis, in particular to determine how antimicrobial therapy promotes bacterial resistance.

“This investigation is a prime example of the One Health approach to research, a recognition that we’re dealing with the same disease processes in animals and in humans,” said lead author Charles Bradley, VMD, DACVP, a lecturer and dermatopathologist of pathobiology in Penn’s School of Veterinary Medicine. “The findings highlight the importance of dogs as a model for human dermatitis and help lay the groundwork for new therapeutic strategies, for example involving microbiome transplants to compete with the harmful bacterial overgrowth, as an alternative to antibiotic therapy.”

Source:  University of Pennsylvania media release