Similarity of the dog and human gut microbiomes in gene content and response to diet

Gut microbes influence their hosts, modulating the link between diet and obesity. Here we study the relationship between the gut metagenomes of dogs, humans, mice, and pigs. By building a gene catalog (containing 1,247,405 genes) we show that the dog microbiome is closer to the human microbiome than the pig or mice microbiomes in gene content. We further demonstrate the similarity of the dog microbiome to the human one with a randomized trial of two diets (high-protein/low-carbohydrate vs. lower-protein/higher-carbohydrate). Diet has a large, reproducible, effect on the microbiome, independent of dog breed or sex. Diet responses were in agreement with those observed in previous human studies, leading to the conclusion that findings in dogs may be predictive of human microbiome results. In particular, a novel finding is that overweight or obese dogs experience larger compositional shifts than lean dogs in response to a high protein diet.