Pet microbiomes: why it may be 2026's biggest pet diet trend

You may have heard of microbiomes, since it’s been a hot topic in human health for a while. In simple terms, microbiomes are the microorganisms that live in our bodies - anything from bacteria and viruses to even fungi and archaea.

Usually, in the right amounts, it’s a symbiotic relationship; we help them a little, then they help us a lot. There are ways to care for your microbiome, and, typically, a well-functioning microbiome is linked with better health, like digestion.

Naturally, since we care about our pets so much, we’re concerned about their microbiome performance, too. After all, better health, better digestion and a happier pet sounds good to us.

Here, we break down what a pet’s microbiome is, why it’s trending and ways you can support your pet’s helpful community of microscopic critters.

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Pet microbiomes - at a glance

• Your pet is basically a walking ecosystem: Trillions of bacteria, fungi, and other tiny organisms live in your pet’s gut. They actually outnumber your pet's own cells!

• New science has changed things: A new study has shown microbiome health in pets is different and more diverse than we previously thought.

• Microbiome organisms are helpful: Unlike parasites, they don’t have harmful impacts on their health if they’re balanced correctly. They help with digestion, immune function and even mental health.

• What goes in your pet’s bowl matters: Diet shapes your pet’s microbiome. Protein and fibre are the main things to keep an eye on, as they help beneficial bacteria.

• Slow and steady wins the gut health race: Gradual dietary transitions, prebiotics, probiotics, and avoiding unnecessary antibiotics help maintain that crucial bacterial diversity our tailmates need.

• Watch for the warning signs: Chronic digestive issues, skin problems, or your pet feeling “off” can all indicate your pet’s microbiome is suffering.

What's a pet’s microbiome, and why should we care?

A pet’s microbiome is an ecosystem of microorganisms. They perform various roles, like helping digestion, regulating the immune system, helping absorb nutrients and supporting our pets’ mental health.

Our pets host an incredible amount of microbial cells (between 10^13 and 10^14 microbial cells to be exact) from over 1,000 bacterial species. While the gut holds the largest amount of these, others live on the skin, mouth and respiratory tract.

These microorganisms help our pets do jobs they can’t do alone, like:

• Breaking down food to extract essential vitamins.

• Helping the immune system by protecting against pathogens or managing inflammation.

• Metabolising amino acids.

• Producing energy through fermentation and the production of short-chain fatty acids.

• Producing vitamins, like B1, B9, B12 and K.

• Regulating the nervous system and metabolic processes.

There’s a lot of science there, but the main thing to remember is this: a pet’s microbiome is important to maintain their health, optimise their nutrition, manage disease and, in some cases, help veterinary professionals diagnose problems.

What changed in 2026?

This year, scientists published the most comprehensive catalogue of pet gut microbiomes called the “Waltham catalogue for the canine gut microbiome”.

The team found 5,753 bacterial genomes with 1,031 distinct strains, which was the biggest analysis on record of pet microbiomes.

The study found:

• 982 new canine-specific bacterial strains, with many new species being involved in fatty acid, vitamin and bile acid regulation. All of these were found to be neutral or beneficial.

• A “core” microbiome, where 240 species make up over 80% of a dog’s gut.

• The existence of carbohydrate-active enzymes shows that the microbiome had a big role in digesting plant-based foods.

• Key differences between canine and human microbiomes, which indicated the uniqueness of a dog’s gut health.

• A new baseline of what a healthy gut means, allowing vets to develop better, more personalised probiotics and gut-friendly diets.

What does this mean for me and my pet?

The end of "human-based" probiotics

What’s changed: Previously, pet supplements were largely based on human gut science. But recent research, like the 2026 study we mentioned, has shown that pet microbiomes are substantially different.

What this means for you: Expect to see a new generation of pet-specific probiotics that actually contain the bacteria pets naturally need, rather than just "repurposed" human versions that might not survive or thrive in a dog's gut.

Vet diagnostics may now be more accurate

What’s changed: A greater understanding of pet microbiomes now means vets can understand more about potential problems in your pet’s gut.

What it means for you: Vets may soon be able to use more precise "microbiome tests" to see exactly what’s missing or overgrown in your pet. This moves care away from "try this food and see" toward "this specific bacteria is missing, let’s replace it".

Health beyond the gut (skin, mood, and weight)

What’s changed: The study highlighted how these new bacteria produce metabolites that regulate inflammation and the immune system.

What it means for you: Improving your dog's gut health may soon be a primary treatment for non-digestive issues, like allergies, anxiety, and obesity.

Personalised nutrition becomes more important

What’s changed: The discovery of a "core" microbiome of 240 species gives a gold standard for what a "healthy pet" looks like, and shows that a personalised approach may be needed per pet.

What it means for you: In the near future, pet food companies may offer diets tailored to your dog’s specific microbiome profile, making sure they get the exact fibres needed to feed their unique "good" bacteria.

How to support our tailmate’s gut health

So, what we put in our pets’ bowls can have a big impact on their microbiome and, by extension, your pet’s health.

That means, as well as making sure our pets’ diet is nutritionally balanced, we also need to make sure we keep a few things in mind when feeding them.

A well-balanced diet

Our pets get a good balance of macronutrients, with a focus on fibre and protein. We have an in-depth guide on pet nutrition that can help guide you here.

In terms of what food to pick, we recommend always choosing a reputable brand that has been formulated with the help of a veterinary nutritionist. This ensures that the food has been correctly balanced for your pet’s needs.

Your chosen diet should feature a named animal protein towards the top of its ingredients list and should be suitable for your dog’s age and size.

Most vets don’t recommend raw feeding at this time due to the proven health and safety risks involved. But there are a whole array of good quality kibble, wet food, or even pre-prepared fresh cooked diets out there to choose from.

Don’t switch food quickly

Don’t switch foods quickly or overnight. We’ve all been there: we make a switch, and there’s a big mess to clean up. We need to do things gradually so our pet’s microbiome can “catch up”.

Studies show microbial communities can shift and stabilise within six days of a diet change but gradual changes are still best. You should mix your pet’s old food in with the new food for at least a week, slowly changing the proportions. Research on puppies found that gradual dietary changes increased beneficial bacteria while reducing diarrhoea rates.

But abrupt changes? They decreased beneficial Turicibacter and Lactobacillus while increasing potentially harmful bacteria. That’s not good news!

Use a mix of prebiotics, probiotics and postbiotics

Making sure that your pet has the right mix of prebiotics, probiotics and postbiotics can support their digestive system. Here’s what each of these are:

• Prebiotics - Fibres which feed beneficial bacteria.

• Probiotics - Beneficial bacteria that support good digestive health.

• Postbiotics - Compounds secreted by good bacteria, like beneficial enzymes and fatty acids.

If your pet is having problems with their digestion, your vet may recommend a mix of these to work together to support your pet’s microbiome.

Warning signs that something's off with your pet's gut

• Chronic burping

• Chronic diarrhoea

• Constipation

• Excessive flatulence

• Itchy skin

• Lethargy

• Recurring ear infections

• Swollen belly

Ways to get those gut bacteria back on track

First of all, it's important to get a diagnosis from a vet. Some of the symptoms on the above list can be associated with medical conditions like pancreatitis. If other illnesses have been ruled out, then you could support your pet’s digestive health by:

• Using a pet-specific digestive supplement, containing pre and probiotics.

• Making a gradual transition to a new diet. For pets with ‘sensitive stomachs’ a highly digestible diet usually works best - speak to your vet for advice on this.

• Making sure your pet is getting enough exercise and mental stimulation.

• Avoiding too many treats or human food scraps, which could be upsetting your dog’s digestive system.

What's actually hurting your pet's microbiome

• Additives.

• Poor-quality food.

• Stress.

• Sudden dietary changes.

• Too many or incorrect antibiotics.

When should you consider microbiome testing?

Microbiome testing might sound like something from the future, but private companies are now offering microbiome testing for pets.

Healthy adult pets may benefit from microbiome testing as part of their preventive care. Think of it as a wellness check for the trillions of little guys keeping your pet’s gut ticking.

Pets with diagnosed tummy issues may need frequent testing, and vets can use this information to track how treatment is going or to diagnose complications.

Always speak to your vet if you have any questions about your pet’s digestive health.

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