Fibre for Dogs: Why It Matters and the Best Sources

Written by Lucy Fitzgerald, Founder, WYLDR. Reviewed by Katie McCaul, RNutr, The Pet Diet.

The short answer: Fibre is the part of plant food a dog does not digest in the small intestine, and it matters more than people think. Soluble, fermentable fibre feeds the beneficial gut bacteria and softens stools, while insoluble fibre adds bulk and keeps things regular. A sensible amount supports digestion, the microbiome and healthy weight. Good sources include pumpkin and chicory root, and most dogs do best with a balanced, moderate level rather than a lot.

Fibre rarely gets top billing on a dog food label, but it quietly does a lot of work. It shapes stool quality, feeds the gut bacteria, helps a dog feel full, and keeps digestion moving. It is also widely misunderstood, with more not automatically being better. This guide keeps it simple: what fibre is, the difference between soluble and insoluble, what it actually does, where to find it, and how much your dog really needs.

What is dietary fibre?

In short: Fibre is the part of plant food that passes through the small intestine undigested. Nutritionists describe it by how well it dissolves in water, how thick it becomes, and how readily gut bacteria ferment it.

Dietary fibre is the plant material that a dog's small intestine cannot break down and absorb the way it does protein or fat. Rather than being a single thing, fibre is a family of components, and veterinary nutritionists tend to describe them by three properties: solubility, which is how well the fibre dissolves in water, viscosity, which is how thick or gel-like it becomes, and fermentability, which is how easily the bacteria further along the gut can break it down.

Fibre also comes in different forms across the diet, from grains to vegetables, and these differ in how soluble they are and how readily the gut bacteria ferment them. Those properties matter because they determine what a given fibre actually does in the body. It is why one high-fibre ingredient behaves very differently from another, and why the type of fibre is often more important than the total amount on the label.

Soluble vs insoluble fibre

In short: Soluble, fermentable fibre dissolves, feeds the gut bacteria and helps soften and moisten stools. Insoluble fibre does not dissolve, adds bulk and speeds transit to support regularity. Most dogs do best with a mix of both.

Soluble fibre dissolves in water and is generally more fermentable, meaning the beneficial bacteria in the gut can feed on it. As they ferment it, they produce short-chain fatty acids that the gut uses, and soluble fibre also helps increase the moisture and softness of stools. This is the fibre most closely tied to the microbiome.

Insoluble fibre does not dissolve. Instead it adds bulk to the stool and helps speed the passage of food through the digestive tract, which supports regularity. Neither type is better in isolation; they do different jobs, and a balanced diet generally provides a sensible mix of the two.

What fibre does for your dog

In short: Fibre supports firm, regular stools, feeds the beneficial gut bacteria, helps a dog feel full for weight management, and contributes to a healthy gut environment through fermentation.

Fibre earns its place in a few clear ways. It plays a large part in stool quality, helping produce the firm, well-formed stools that signal comfortable digestion. Fermentable fibre feeds the beneficial bacteria in the gut and, through the short-chain fatty acids they produce, supports a healthy gut environment. You can read more about that side of things in our guide to dog gut health.

Fibre also influences appetite and satiety, which is why it features so often in weight-management diets: it can help a dog feel satisfied without piling on calories. In short, fibre is not filler. It is a working part of the diet that touches digestion, the microbiome and healthy weight all at once.

Prebiotic fibre and the gut

In short: Prebiotic fibres are a special group of fermentable fibres that specifically feed the beneficial gut bacteria. Chicory root, a natural source of inulin, is one of the best known.

Within the fermentable category sits a particularly useful group: prebiotic fibres. These are the fibres that the beneficial bacteria feed on most readily, so rather than just passing through, they actively nourish the good population in the gut. Chicory root is one of the most studied, as a natural source of a fibre called inulin.

This is the difference between adding fibre for the sake of it and choosing a fibre that does a specific job. A prebiotic fibre is targeted: it feeds the bacteria you want to encourage, which is why it comes up so often in any serious conversation about gut health.

Best sources of fibre for dogs

In short: Good sources include pumpkin, chicory root, beet pulp and certain vegetables. Different sources bring different types of fibre, which is why variety and balance help.

Plenty of everyday ingredients supply useful fibre. Pumpkin is a popular, gentle source that many owners reach for. Chicory root supplies prebiotic inulin. Beet pulp is a well-regarded moderately fermentable fibre used in many quality dog foods, and vegetables such as carrot and green beans contribute fibre too.

Because each source leans towards a different type of fibre, the aim is a sensible balance rather than loading up on any single one. A good, balanced diet usually provides this already, and a targeted prebiotic fibre can top up the specific job of feeding the gut bacteria.

How much fibre does a dog need?

In short: Fibre is not considered an essential nutrient for dogs, but a modest amount, generally under about 5% of the diet and from a mix of fibre types, supports a healthy microbiome. More is not better: too much, especially fermentable fibre, can cause gas, loose stools and discomfort.

Fibre is not classed as an essential nutrient for dogs the way protein and fat are, but that does not mean it is not useful. A modest amount, generally under about 5% of the diet and from a mix of fibre types, is a sensible level to maintain a healthy microbiome, and most complete diets are formulated around this. The key point is that fibre is a case of the right amount, not the most possible, and if you are adding extra, introduce it gradually, because a microbiome that is not used to it can react with gas or loose stools. Piling it on can backfire.

Too much fibre, and fermentable fibre in particular, can lead to excess gas, loose stools, bloating and discomfort. Some fibres are also unsuitable for certain medical conditions, where the wrong choice can make things worse. So while fibre is genuinely useful, it is best kept in balance, and any dog with an ongoing digestive problem should be guided by a vet rather than a bag of high-fibre food.

Where fibre fits

In short: Most dogs get enough fibre from a good diet. A targeted prebiotic fibre is a sensible way to support the gut specifically, offered as everyday support rather than a fix.

For most dogs, a good, balanced diet already delivers a reasonable amount of fibre. Where a targeted prebiotic fibre adds value is in doing one specific job well: feeding the beneficial gut bacteria as a steady daily habit.

This is why chicory root is one of the five ingredients in WYLDR's Every Dog Every Day, included as a source of prebiotic fibre to help support a healthy gut and microbiome, alongside the other things a typical bowl can miss. It is everyday support, described as exactly what it is. If you want the wider picture, our guide to whether dogs need supplements explains where a daily supplement genuinely fits.

Frequently asked questions

Why do dogs need fibre?
Fibre supports firm, regular stools, feeds the beneficial gut bacteria, helps a dog feel full for weight management, and contributes to a healthy gut environment through fermentation. It is a working part of the diet, not filler.

What is the difference between soluble and insoluble fibre for dogs?
Soluble, fermentable fibre dissolves in water, feeds the gut bacteria and helps soften and moisten stools. Insoluble fibre does not dissolve, adds bulk and speeds transit to support regularity. Most dogs do best with a mix of both.

What are good sources of fibre for dogs?
Good sources include pumpkin, chicory root, beet pulp and vegetables such as carrot and green beans. Because each leans towards a different type of fibre, a sensible balance is better than loading up on one.

How much fibre does a dog need?
Fibre is not classed as an essential nutrient for dogs, but a modest amount, generally under about 5% of the diet and from a mix of fibre types, helps maintain a healthy microbiome. More is not better, and any extra should be introduced gradually.

Can a dog have too much fibre?
Yes. Too much fibre, especially fermentable fibre, can cause gas, loose stools, bloating and discomfort. Some fibres are also unsuitable for certain medical conditions, so ongoing digestive issues should be guided by a vet.

Is chicory root a good source of fibre for dogs?
Yes. Chicory root is a natural source of inulin, a prebiotic fibre that specifically feeds the beneficial bacteria in the gut, which is why it is one of the most studied prebiotic sources in pet nutrition.

Sources

• Montserrat-Malagarriga M, et al. "The Impact of Fiber Source on Digestive Function, Fecal Microbiota, and Immune Response in Adult Dogs", Animals (2024, peer-reviewed): link
• Moreno AA, Parker VJ, Winston JA, Rudinsky AJ. "Dietary fiber aids in the management of canine and feline gastrointestinal disease", Journal of the American Veterinary Medical Association (JAVMA, 2022, peer-reviewed): link
• Bosch G, et al. "The effects of dietary fibre type on satiety-related hormones and voluntary food intake in dogs", British Journal of Nutrition (2009, peer-reviewed): link
• de Godoy MR, Kerr KR, Fahey GC Jr. "Alternative dietary fiber sources in companion animal nutrition", Nutrients (2013, peer-reviewed): link
• National Research Council (2006), Nutrient Requirements of Dogs and Cats. Washington, DC: National Academies Press.
• Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, Sharp CR (2024), Small Animal Clinical Nutrition, 6th edn. Topeka, KS: Mark Morris Institute.