What are prebiotics for dogs and what are the benefits?

At a glance

• Prebiotics are fibres your dog can't digest but the good bacteria in their gut can, so they work as food for a healthy gut
• Probiotics are the live bacteria themselves, and postbiotics are inactivated bacteria or their parts: three different things that often get mixed up
• Chicory root (a natural source of inulin), fructooligosaccharides (FOS) and mannanoligosaccharides (MOS) are among the most studied prebiotics in dogs
• In studies in dogs, prebiotics changed the mix of gut bacteria and increased short-chain fatty acids, compounds those bacteria make, some of which the gut lining uses for energy
• Too much at once causes wind and looser stools, so prebiotics work best in small, steady amounts as part of everyday food

What are prebiotics for dogs?

Prebiotics are fibres that your dog can't digest but the good bacteria in their gut can, and their main benefit is feeding those bacteria so they can keep the gut working well. If your dog's gut bacteria were a garden, prebiotics would be the fertiliser.

Most of what your dog eats is broken down in the stomach and absorbed in the small intestine. Prebiotic fibres pass through largely untouched and reach the large intestine, where gut bacteria ferment them. Scientists define a prebiotic as something the gut's bacteria use selectively, in a way that benefits the animal they live in. That last part matters: a fibre only counts as a prebiotic if there is evidence it does some good.

The community of bacteria living in the gut is called the microbiome. A well-fed microbiome is a big part of good digestion, which is why prebiotics turn up in so many foods aimed at dogs with sensitive stomachs.

What's the difference between prebiotics, probiotics and postbiotics?

Prebiotics feed the good bacteria already in your dog's gut, probiotics add helpful live bacteria to it, and postbiotics are inactivated bacteria or their parts that still bring a benefit. The names are confusingly similar, so here they are side by side.

Vets mostly use probiotics for specific blips. The PDSA lists diarrhoea after antibiotics, stress or a sudden change of food as all common reasons why vets advise them, and says a course often lasts three to five days. Prebiotics are more of an everyday thing, because they work with the bacteria your dog already has.

What are the benefits of prebiotics for dogs?

The main benefit of prebiotics for dogs is a better-fed gut: studies show they change the mix of gut bacteria and boost the useful compounds those bacteria make.

Several studies in dogs back this up. In overweight Beagles, inulin-type prebiotics increased short-chain fatty acids and shifted the balance of gut bacteria within two weeks. In another study, dogs given FOS had lower levels of some of the compounds that make poo smelly. Dogs given MOS, which comes from yeast, also showed a trend towards more Lactobacillus, one of the bacteria groups linked to a healthy gut.

Most of this research uses small groups of dogs, so it's best to think of prebiotics as steady, everyday support for the gut rather than a fix for any particular problem. If your dog has ongoing tummy trouble, start with your vet.

Which foods are natural prebiotics for dogs?

Chicory root is a popular natural prebiotic for dogs, because it is one of the richest natural sources of inulin. Inulin and FOS, a shorter version of the same type of fibre, are among the most studied prebiotics in dogs. MOS comes from the cell walls of yeast. Other fermentable fibres, such as the pectin in apples, also give gut bacteria something to work with.

Not all fibre is a prebiotic. Cellulose, a common bulking fibre, gives gut bacteria very little to ferment, which is why researchers use it as the ‘no prebiotic’ comparison in studies. Fermentable fibres such as inulin are the ones that feed the gut, so the kind of fibre in your dog's diet matters as much as the amount.

Every Marleybones Pantry Fresh® recipe includes chicory root, so there's a natural prebiotic in every bowl rather than as an extra step. It sits alongside real meat and vegetables, gently cooked at an average temperature of 89°C.

Does my dog need a prebiotic supplement?

Most healthy dogs don't need a prebiotic supplement if their everyday food already contains a prebiotic source such as chicory root. A supplement is useful for dogs that need a bit more help with their digestion and stool quality.

The Marleybones Gut Health Supplement is a daily chew that pairs two prebiotics, MOS and chicory root, with psyllium and pumpkin to support stool consistency. If your dog's stomach is often upset, see your vet before reaching for a supplement, so you know what's behind it.

Can prebiotics upset a dog's stomach?

Yes, too much at once can. Gut bacteria make gas as they ferment fibre, so a big jump in prebiotics leads to wind, and in one study higher doses made stools slightly wetter. Small, steady amounts are the way to go, which is one reason prebiotics work well as part of a complete everyday food.

If you're adding a supplement, build up gradually and follow the serving guide. Make sure your dog stays well hydrated too, as plenty of fresh water helps their digestion when you add in a supplement like a prebiotic.

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FAQs

Are prebiotics safe for dogs?

Yes. Prebiotics such as chicory root are widely used in complete dog foods and are safe at normal levels. The main side effect is wind or looser stools if a dog gets a lot more than they're used to all at once.

How long do prebiotics take to work in dogs?

In studies in dogs, changes in gut bacteria and the compounds they make showed up within about two weeks. Keep things consistent, as the benefit comes from steady, everyday intake rather than the odd big dose.

Do dogs need prebiotics and probiotics together?

Not usually. A healthy dog on a balanced diet with a prebiotic source gets everyday support for the bacteria they already have. Probiotics are more often a short course for a specific blip, such as diarrhoea after antibiotics, so ask your vet if you think your dog needs one.

Can puppies have prebiotics?

Yes, as part of a complete food. Every Marleybones Pantry Fresh® recipe is complete for all life stages, including puppies, and contains chicory root. Check with your vet before giving a puppy any separate supplement.

Do all dog foods contain prebiotics?

No, so check the ingredients list for chicory root, inulin, FOS or MOS. A complete food with a prebiotic in every recipe, like Marleybones Pantry Fresh® with its chicory root, covers it in your dog's everyday bowl.

Does Marleybones contain prebiotics?

Yes. Every Marleybones Pantry Fresh® recipe includes chicory root, a natural source of the prebiotic inulin. Our Gut Health Supplement adds MOS and chicory root for dogs that need extra support.

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Sources

• Gibson GR et al. (2017) ISAPP consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology
• Alexander C et al. (2018) Effects of prebiotic inulin-type fructans on blood metabolite and hormone concentrations and faecal microbiota and metabolites in overweight dogs. British Journal of Nutrition
• Swanson KS et al. (2002) Supplemental fructooligosaccharides and mannanoligosaccharides influence immune function, ileal and total tract nutrient digestibilities, microbial populations and concentrations of protein catabolites in the large bowel of dogs. Journal of Nutrition
• Propst EL et al. (2003) A dose-response experiment evaluating the effects of oligofructose and inulin on nutrient digestibility, stool quality, and fecal protein catabolites in healthy adult dogs. Journal of Animal Science
• PDSA: Probiotics for dogs and cats

Last updated: 21 October 2026 · Reviewed by Molly Buckmaster BVM BVS MRCVS