The hypothesis of this project is that obese dogs have a particulaar set of microbiota that differs from their lean counterparts, which allows energy to be more efficiently harvested from the diet and causes increased inflammatory tone resulting from a compromised epithelial integrity. The objectives are to determine the predominant GI microbial species in obese dogs and compare it with lean dogs and whether different macronutrients in a diet leads to weight gain by influencing the composition of the microbiota