It's an age-old partnership: dogs and their humans. The relationship is tens of thousands of years in the making and has left our furry friends so in tune with us, they can even read our emotions.
Now, scientists have revealed another surprising facet of that connection. As Kat Eschner reports for Popular Science, researchers found that the microbes of dog and human poop are quite similar. The study, published in the journal Microbiome, suggests that our microbiota are so similar that our canine companions might actually be better subjects for human nutrition research than the more commonly used pigs or rats.
The gut microbiome, also known as gut flora, is the collective bacteria and microorganisms that live in the digestive system, Sarah Sloat writes for Inverse. The burgeoning field of research is on the forefront of health science, with recent studies suggesting that your microbes influence the health of your immune system, weight and even mental health.
For the latest study, researchers from the European Molecular Biology Laboratory and Nestlé Purina Research looked at the gut microbiome of 32 beagles and 32 Labrador retrievers by collecting their poop. As Eschner explains, half of the dogs were overweight, and the other half were a healthy weight.
They started by feeding them all the same Purina diet for four weeks. They then got a poop sample. The researchers then grouped the dogs randomly and then fed one group a high-protein, low-carb diet and the other a low-protein, high-carb diet. After another four weeks, they collected another poop sample.
The researchers then sequenced the DNA to take a look at the microbe diversity. They found that the microbiomes of dogs who were at a healthy weight at the start of the study changed less than those of the overweight dogs. This suggests that the flora of leaner dogs is more resilient, Srimathy Sriskantharajah reports for BioMed Central, which publishes the journal Microbiome. Humans respond similarly to diet changes, according to a press release.
The study also compared the array of flora to that of humans, mice and pigs. And surprisingly, dogs’ gut microbiome was much more similar to humans’ than pigs or mice—two species commonly used in the development of human medicine.
The researchers did not expect to find such canine-human microbiome similarities. But as lead author Luis Pedro Coelho tells Eschner, the dog flora “has some of the same species [of bacteria] as the human’s, but different strains.”
The researchers suggest that domestication, and our long relationship with dogs, has something to do with why our flora is so similar. As the researchers write in the study, the sharing of resources early in domestication, including food, likely helped shape the modern canine.
The latest study adds to the mounting evidence of human-dog similarities. In one 2013 study, researchers even found that dog owners had similar skin microbiomes to their furry friends. And the skin, gut and tongue microbiota were all more alike among family members compared to outsiders.
The new study shows just how closely related the floras are. Researchers might even be able to use dogs as a model for human gut microbiome research, Coelho says in a statement.
“These findings suggest that dogs could be a better model for nutrition studies than pigs or mice,” he says, “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.”