Back to Blog

Natural born carnivores?

The debate over whether our domestic dogs are pure carnivores or are well adapted to a more omnivorous diet has been raging in the pet nutrition community for many years, and while there have been strong arguments for both positions, there has been little in the way of firm scientific evidence to back them up. However, this could be changing as recent developments in our understanding of the canine gut microbiome are starting to uncover more about how the bacterial populations in our dogs’ digestive tracts are adapted to different types of diet.

May 1, 2024 • 3 min read

Dr Joe Inglis BVSc MRCVS

Head of Veterinary Sciences

What is undoubtedly true is that compared with classic omnivores such as humans, dogs do have a simpler, shorter digestive tract which is better optimised for digesting high protein animal proteins. However, it is also the case that when compared to true obligate carnivores like cats, dogs’ digestive tracts have significantly more small intestine with 23% of the total gastrointestinal volume being small intestine, which is more consistent with omnivores than cats where the small intestine occupies around 15%. Longer digestive tracts are generally associated with the digestion of plant materials as these take longer to break down than nutrients of animal origin.

Dogs also do not rely to the same degree on the action of the gut microbiome for maintaining energy balance as other animal species where the output of the microbes in the digestion provide a significant amount of the animal’s energy supply. However, although they have clearly evolved to primarily digest animal proteins, compared to pure carnivores such as cats, the science supports the fact that domestic dogs can digest, absorb and metabolise a considerable amount of dietary carbohydrates such as grains, even if this wasn’t a food source they specifically evolved to utilise. A study from 1994 showed that dogs could digest more than 98% of the carbohydrate in their diet, providing strong evidence that they are well adapted to omnivorous diets.

When it comes to the bacterial populations in the gut microbiome, the picture becomes a little more complicated, with a key difference between the microbial population of omnivorous animals and dogs. This relates to the relative predominance of Fusobacterium species in canine gut microbiomes which can account for 10% or more of the species present in a normal canine microbiome. While the exact function of Fusobacteria in dogs is still unclear, they are thought to have a key role in protein digestion in primarily carnivorous diets, providing evidence to support evolutionary adaptation to a meat-based diet.

So, what conclusions can we draw from the latest science in the carnivore versus omnivore debate? Based on all of the available evidence, including our increasing understanding of the gut microbiome, it is clear that dogs cannot justifiably be classified as pure, obligate carnivores in the same way that cats can be - their digestive tracts, and proven ability to digest plant materials including carbohydrates, point to a digestive tract that is able to deal with a much more varied diet than pure meat alone. Therefore, while the debate will undoubtedly continue, the science is clearly pointing towards dogs being omnivores, even if they are closer to the carnivore end of the dietary spectrum than other omnivores, ourselves included.

Ready to start your BIOME9 journey?

Order GutDiscovery® test kit & personalised health report

Frequently asked questions

The microbiome is the name given to the collection of microbes, mostly bacteria, but also fungi and protozoa, that exist within your dog’s gut. It is a diverse and complex microbial community which can directly affect health and wellbeing. We know that 90% of a human’s body cells are microbes, with only 10% being human cells – it’s just that human cells are markedly larger than the microbes. It’s similar for our four-legged friends. Testing the microbiome gives us an idea of exactly which bacteria are present in your dog’s gut and this can help indicate existing or future health problems.
A healthy diversity within the microbiome has been found to be an accurate indicator of overall health and wellbeing. If your dog appears healthy, but has an imbalance in their microbiome, then this could be an indicator of a potential future health issue. If your dog has any existing health complaints, then improving the health of their microbiome can help to improve immune system health and overall wellbeing, as well as improving disease symptoms.
Testing and treatment have the potential to help with a whole range of different health complaints. The immune system is very closely associated with the gut, so any imbalance in the microbiome can influence immune system health, overall vitality and wellbeing. Our supplement recommendations are also tailored to your individual dog, with specific ranges designed to help with gastrointestinal inflammation, joint problems, allergies and skin complaints, to name a few.
All you need to do is order a kit online and fill in our questionnaire about your dog and their general health. We will then send the kit out to you by post. You then just need to collect a sample and return it to us, again by post. Once the test is performed, we will email the results directly to you.
You do not need to get your vet’s permission to test, or talk to them about performing the test beforehand. We do recommend that you pass on a copy of your test results to your regular vets, as it may help them in understanding your pet’s current health, and any future complaints they may have.