Landmark Study Dog's Gut Microbiome

The science is clear: your dog's gut isn't just tolerating plants—it's designed to turn them into the very fuel that keeps the whole body thriving.

Updated on March 22, 2026 by Just Be Kind Dog Food Arielle

If you've ever had to defend your choice to feed your dog a plant-based diet, the latest research from the Waltham Petcare Science Institute offers some compelling backup. Walthams Petcare Institute is owned by Mars Petcare who own Royal Canin, Dreamies, Pedigree - why do they not listen to their own studies and produce a plant-based option full of natural plant fibres and no processed animal byproducts?! (Read about exposing Hills, Purina and Royal Canin)

The landmark 2026 study by Walthams Petcare Science Institute (read full study here) —the most comprehensive mapping of the canine gut microbiome ever conducted—found that a healthy dog's gut bacteria are extraordinarily well-equipped to process plant fibres, with an average of 71 specialised enzymes per species dedicated to breaking them down.

Study by Walthams on dog's gut microbiome

When these fibres are fermented, nearly half the gut bacteria by volume produce butyrate, a powerful compound that supports everything from brain health to joint function, immune strength to a healthy gut lining.

The science is clear: your dog's gut isn't just tolerating plants—it's designed to turn them into the very fuel that keeps the whole body thriving.

Their study ends with this conclusion:

"This work gives entirely new perspectives on the functional capabilities of the canine gut microbiome, suggesting the canine microbiome is distinct, presumably having evolved to its host, diet, and environment over several millennia."

Far from being a compromise, a well-formulated complete plant-based diet may actually be giving your dog's microbiome exactly what it needs to do its best work and keep your dog as healthy as possible!

VISIT JUST BE KIND FOR THE BEST WET DOG FOODS FULL OF WHOLEFOOD FIBRES

VISIT JUST BE KIND FOR DRY FOOD EVEN CONTAINING BIOTIC PROTEIN!

Want to find out more about the amazing effects of a healthy gut on your dog's overall health?

This is Dr Arielle's absolute favourite topic! She spoke at Vegfest in London amongst the plant-based health professionals as did you know that we share the same gut microbiome as our dogs?!

With this knowledge, it makes so much sense that we then see the same reduction in signs of chronic inflammation and auto-immune conditions in our dogs when both us and our dogs follow a nutritionally complete wholefood plant-based diet.

JUST SO MANY IMPORTANT GUT FRIENDLY FACTS TO SHARE (and they may even help you with your own gut health!!)

What is the gut microbiome?
Why a healthy gut microbiome is so important.
How to keep the gut microbiome healthy.
Behavioural signs in your dog which may suggest that their gut microbiome needs to be improved.
How the gut microbiome affects the skin
What are prebiotics, probiotics, postbiotics and even biotic protein?!

It is common knowledge that when changing the diet of your dog, always try to do it slowly; reducing the previous diet-fed and slowly introducing the new food over a few weeks.

Dogs are opportunistic omnivores and actually, they are ‘scavengers’. Think of what they try to eat on walks while sniffing in the bushes!  They should cope with changes in what they are fed really well, but sensitive breeds need it introduced slowly.

The reason for this is to allow your dog’s gut microbiome to adapt to the increase in fibre and natural plant-based whole foods in the diet.

What exactly IS the gut microbiome?

Your dog’s ‘microbiome’ in their gut is a balance of:

Trillions of bacterial cells.
Fungi.
Viruses.

These number of these cells in your dog's gut is 10x higher than all the other cells in your dog’s body - a true wonder ‘microbiome’!

What we feed our dog has a direct impact on their gut health. A diversity of foods has the biggest positive effect.

If home cooking whole foods for your dog, aim to feed at least 30 different plants a week. (The same goes for us). Please see our 4 home cook recipes that we have on this website that have exactly that - 30 vibrant colours including nuts, seeds, pulses, whole grains, fruits, spices, herbs and colourful vegetables for your dog!

What is the difference between prebiotics, probiotics and postbiotics?

Prebiotics

Prebiotic fibre is not digested until later in the digestion process.
Prebiotics are like the 'fertiliser' for the probiotics to help them thrive.
Brown rice, the skin of apples, cabbage, beans, and many others are examples.
Prebiotic fibre goes through the small intestine undigested.
It is fermented when it reaches the large colon.
Most commercial vegan foods have the addition of prebiotics such as inulin (chicory root), yukka, pineapple stems and some like Give A Dog A Bean and Jumping Jack, even have the addition of papaya and psyllium husks - wonderful natural prebiotics to act as 'fertiliser' for the probiotics.

Chicory heart

These prebiotics feed beneficial bacteria colonies (including probiotic bacteria). They help to increase the number of desirable bacteria (the good guys!) in your dog’s digestive system. These desirable bacteria are associated with better health and reduced disease risk.

A diet high in processed foods containing sugar or too many prebiotics can also feed harmful gut bacteria. It is important to feed the right amount.

When home-cooking, we encourage the addition of boiled, steamed or roasted cauliflower, cabbage, celery, kale, carrots and asparagus. These vegetables are important prebiotics and are beneficial to our dog’s gut health.

(Remember that our dogs cannot eat onions, chives or leeks! These are good prebiotics for us but not for our dogs)

Raw fed dogs also have signs of dysbiosis ie too many of the harmful bacteria in the gut! (Al-Shawaqfeh et al, 2017)

What exactly are Probiotics?

Probiotics are live beneficial bacteria that enhance the gut health of your dog.
They are naturally created by the process of fermentation in certain foods, or by the addition of probiotics to the diet.
Tempeh (fermented soybeans) is the easiest and healthiest natural probiotic you can give to your dog - rich too in protein and dogs LOVE tempeh! (we hide Ruff's tablets in tempeh!!)
Probiotics support the production of short-chain fatty acids (SCFAs), such as butyrate that can support the growth of beneficial bacteria.
Some strains generate essential vitamins, such as B vitamins (e.g., B1, B2, B3, B5, B6, B7, B9, and B12) and vitamin K. These vitamins play key roles in metabolism, blood clotting and overall health.
They produce enzymes that assist with digestion of nutrients.
They help maintain proper bowel health and function.
JUST BE KIND Supplement contains probiotics, so it must NOT be heated but added to cooled cooked food.
Other sources include plant-based and enriched yoghurts that can be found in Sainsbury as shown below

Coconut gut yoghurt

Why The Immune System Needs Probiotics

About 90% of your dog’s immune system is in his gut, so diverse gut bacteria help support the immune system.
Probiotics ferment food to create short chain fatty acids (SCFAs) in your dog’s colon ... and they too have some important jobs.
SCFAs help ... Nourish friendly bacteria
Crowd out bad bacteria
Support the gut's mucosal lining, keeping cells close together
Lower glucose and manage obesity
Defend against food allergens
Build T-cells in the immune system
Absorb nutrients like calcium, magnesium and iron

And now what are Postbiotics!?

These good gut bacteria or probiotics that we mention, just want to thrive, grow and multiply, and they also produce their own 'metabolites' or food called short chain fatty acids.

These enhance the gut barrier by forming a protective layer that lets the 'good guys' in ie proteins, antioxidants, important vitamins, while at the same time it stops the entry of the free radicals, cancer cells, viruses, harmful bacteria etc.

70% of your dog’s immunity is regulated by gut flora!

Some of the gut bacteria such as Lactobacillus reuteri, produce a 'food' called reuterin that is a potent antibacterial metabolite!

There is even a published study here (Sordillo and Heldrich 2025) that shows how postbiotics can reduce itching in dogs!

Read much more about postbiotics by clicking on the image below.

Where can we get postbiotics to enhance the gut health of our dogs?

The easiest and most satisfying way to supply your dog with postbiotics ie the valuable 'food' of the good gut bacteria; is to treat your dog with our Marshmallow Bites or Shroom Paws homemade treats!!!

Both delicious treats contain the addition of these postbiotics to enhance the health of your dog; and with shiitake mushroom and turkey tail mushroom being high in beta glycans that the good bacteria just LOVE to feed on, these treats are very important for your dog's digestion!

With our Marshmallow Bites, we have included marshmallow root and slippery elm that both enhance the gut health of your dog too, so invaluable for dogs with gut issues!

(Try our HAPPY GUT HAPPY MUTT PACKAGE that includes a pack of Shroom Paws and a pack of Marshmallow Bites)

What exactly is Biotic Protein and why do we want to give it to our dogs?

Biotic protein is protein made from one species of thriving bacteria called Methylococcus capsulatus (Bath) as it was first discovered in the hot springs of Bath! This particular bacteria has a high nutrient density and an excellent digestibility in dogs and is grown in huge vats as it produces protein that is bioidentical to beef protein in amino acid profile!

Do you love the science? Read more here about the complete genome sequence of Methylococcus capsulatus (Bath)

Thanks to these outstanding properties, Methylococcus capsulatus (Bath) was chosen as the main protein source for Dry Dog Food MicroBell. Dogs with food intolerances especially benefit from this gentle protein source, which is easy to digest and does not burden the gastrointestinal tract as it is high in Glutamic acid (as shown below) that soothes the gut lining.

Feedkind high in glutamic acid

Read more about remarkable biotic protein used in Microbell dry dog food below:

What about antibiotics  - what effect do they have on our dog’s gut flora?

There are certain antibiotics given to dogs when they suffer from digestive complications and colitis (inflammation of the large bowel). They tend to be given an antibiotic called Metronidazole or tradename Metrobactin. These will destroy the gut bacteria. Its effects can last for up to 6 months. It is even more important to look after the gut microbiome of these dogs with healthy pre and probiotics.

We highly recommend using NUTRAVET Probiotic capsules if your dog has had a course of antibiotics.

Vets will normally prescribe Pro-kolin as a treatment to replace the gut bacteria and harden any diarrhoea. There is a cheaper option called Regutums.

Do we really share the same gut microbiome as our dogs?

It was through a study by Luis Pedro Coelho, who found that dogs have a similar gut microbiome to humans. 

Dr Coelho explains from his study on weight issues in dogs and the gut microbiome:

“These findings suggest that we could potentially use data from dogs to study the impact of diet on gut microbiome in humans, and humans could be a good model to study the nutrition of dogs.” 

Wonderful - for once we could be used as the ‘guinea pigs’ for our dog’s nutrition as we all share the same gut microbiome!!

The gut bacteria is similar among families (including your family dog), and even differs in certain areas in the UK for example. It is thought that this is due to the water levels with higher levels of chlorination so one small tip is to use filtered water in your dog’s drinking bowl. We use a Brita filter as a family and in Ruff’s bowl.

Will feeding fresh food affect my dog's skin?

Yes! Studies have shown that feeding a fresh food diet with wholefood natural ingredients that stimulate a healthy gut microbiome WILL promote changes in the bacteria of your dog's skin compared to dogs on a dry food diet! This is SO important for dogs with allergic skin conditions.
Read the published paper here .
Read an assessment of the paper here as a pdf.