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New publication: Comparison of the fecal microbiota of adult healthy dogs fed a plant-based (vegan) or an animal-based diet 

We are excited to announce a new publication! Brooklynn Liversidge and colleagues recently published their new article Comparison of the fecal microbiota of adult healthy dogs fed a plant-based (vegan) or an animal-based diet in Frontiers in Microbiology. Read on for a short summary of their research and findings below.  


The purpose of this study was to examine the fecal microbial composition and structure in response to an experimental vegan diet compared to a commercially available animal-based diet.  


This study was conducted as part of a larger previously published study in client-owned healthy adult dogs[1].  

A total of 61 healthy adult dogs were recruited to participate in this trial. For four weeks before the start of the study, all dogs were provided the same, animal-based, dog food. After this adaptation period, dogs were split into two groups: one group continued on the animal-based dog food, and the other group was switched to a plant-based (vegan) diet for 12-weeks.  

The plant-based food used in this trial was formulated specifically to be as close as possible in nutrients to the animal-based food – despite the different ingredients. During the trial both owners and the research team were blinded to which food was being fed to each dog, and remained blinded until after all data was analyzed.   

During the study, we collected fecal samples from the dogs at the beginning and end of the 12-week period. These samples were analyzed to study the dogs’ gut bacteria. We used a technique called polymerase chain reaction (PCR) to amplify bacterial DNA and then sequenced it. Statistical analyses were performed to compare changes in the dogs’ gut microbiota after they consumed either the plant-based or meat-based diet. 

Summary of Key Findings

The results from the present study revealed that feeding a completely plant-based (vegan) diet for 12 weeks had only small effects on their gut bacteria compared to a traditional animal-based diet. Dogs have been domesticated by humans for many years, which has caused their gut bacteria to have various similarities. This led to the idea that changes in gut bacteria in humans might also occur in dogs. In humans, vegan diets cause changes in gut bacteria, with more bacteria that helps with fermentation of carbohydrates and fewer bacteria that helps in fermentation of animal protein and fats. In the current study the bacteria only had minor changes on highest bacteria level classification (phylum) and no significant changes on the more specific bacteria level classifications (family and genus). These results showed that the way dogs’ gut bacteria changed on a plant-based diet was different from what is usually reported in humans consuming a vegan diet.  


As a result of domestication, dogs and humans have similar gut bacteria. In humans, the gut bacteria are influenced by dietary changes such as consumption of a vegan diet. In the current study, the bacteria found in the feces of dogs eating a plant-based diet did not change drastically when compared to the dogs eating the traditional animal-based diet.  

Previously, it was mentioned that the diets used in this study were made just for this trial and that the nutrient profiles were almost the same despite different ingredients used. It is important to note that in humans, a vegan diet usually has very different ingredients and nutrients compared to a diet with animal products. This means that changes in gut bacterial might be more influenced by the nutrients in the diet, not just the different ingredients. If you want to learn more about the difference between nutrients and ingredients, follow this link to our earlier post titled: Understanding Nutrients and Ingredients.   

Research Funding:  

Natural Sciences and Engineering Council of Canada (NSERC) & Petcurean Pet Nutrition Ltd

Written by: Brooklynn LiversidgeBSc.H., MSc., PhD. Candidate

Reviewed by: Dr. Adronie Verbrugghe, DVM, PhD, Dip ECVCN, Associate Professor and Royal Canin Veterinary Diets Endowed Chair in Canine and Feline Clinical Nutrition,  Hannah Godfrey, BSc.H., MSc., PhD Candidate

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