Probiotics for Dogs: A Complete Guide to Gut Health
Probiotics have become one of the most popular supplements for supporting our dogs’ health; and with good reason. The gut is home to a vast community of microorganisms, collectively known as the gut microbiome, which plays an important role in digestion, nutrient production, immune function and overall wellbeing.
Maintaining a diverse and balanced microbiome can therefore be an important part of supporting your dog’s health, and this is where probiotics can help. These beneficial microorganisms can support the natural balance of bacteria within the gut, particularly at times when that balance may have been disrupted.
But not all probiotics are the same. Different species and strains can have different properties, and probiotic supplements can vary considerably in their formulation, strength and intended use.
So, which probiotics should you choose for your dog, what should you look for in a good-quality supplement, and where do prebiotics fit into the picture? In this guide, we take a closer look at the canine microbiome and explore the different types of probiotics and prebiotics available, how they work and how to choose the most appropriate support for your dog.
What Is The Microbiome?
Your pet’s digestive system is the largest organ in the body and is home to trillions of bacteria and other microorganisms that play an essential role in their overall health. While only small numbers of bacteria live in the stomach, the population grows throughout the intestines, with the largest concentration found in the colon. Together, these microorganisms form what is known as the microbiome; the collective genome of the microorganisms that share body space.
The microbiome is a complex ecosystem that works continuously to support digestion, nutrient absorption, plays a vital role in regulating the immune system and overall wellbeing. It performs many important protective functions, helping to defend the body against harmful invaders such as bad bacteria, viruses, and yeast. The microbiome can even influence behaviour and mood through communication with the brain, including signalling hunger and other bodily responses.
Your cat or dog interestingly has more intestinal bacteria than we do, with their microbes outnumbering their cells ten to one. Their gut is designed to handle an incredible bacterial load.
Every dog has a unique microbiome, shaped by factors such as diet, lifestyle, environment, and even early life experiences. Just like a fingerprint, no two microbiomes are exactly the same.
Although the largest and most diverse populations of beneficial bacteria and other microorganisms are found within the digestive tract, microbial communities also naturally live throughout your dog’s body, including on the skin and within the ears, mouth and respiratory tract. Each of these areas has its own distinct microbiome, where beneficial microorganisms form part of the body’s natural ecosystem and help maintain a balanced environment. When this microbial balance is disrupted, a state known as “dysbiosis”, less desirable microorganisms may have greater opportunity to flourish, potentially contributing to problems affecting the skin, ears, mouth or digestive system.
This is also why it is important to protect your pet’s skin microbiome. Over-shampooing, particularly with harsh or unsuitable products, can disrupt the skin’s natural oils and microbial community, potentially disturbing the delicate balance of microorganisms that help maintain a healthy skin barrier. Choosing gentle, pet-appropriate grooming products and avoiding unnecessary bathing can help preserve this natural ecosystem.
What Are Probiotics and Prebiotics?
Probiotics are live microorganisms that help support a healthy digestive system and can confer overall wellbeing. The word probiotic means “for life” – it comes from the Greek and Latin words pro (meaning "for" or "in favour of") and bios or biōtikos (meaning "life"). It was created as the opposite of the word antibiotic, which means "against life".
Often referred to as “good bacteria,” these beneficial microbes naturally live in your dog’s gut, where they help maintain a balanced intestinal environment. In addition to beneficial bacteria, some types of yeast are also considered probiotics and can play an important role in supporting gut health and immune function.
Prebiotics work alongside probiotics by providing a source of nourishment for the beneficial bacteria living in your dog’s gut. Typically made up of specific types of fibre that resist digestion, they reach the large intestine where they are broken down by gut bacteria (and act as food for the beneficial gut bacteria), helping beneficial populations to grow and thrive.
While probiotics introduce beneficial microorganisms, prebiotics help support the environment they need to flourish, making the two a useful partnership for maintaining a healthy, balanced gut microbiome. For more information about prebiotics please refer to our blog.
Why Gut Health and Probiotics Matter for Your Dog
A healthy gut microbiome is an important foundation for your dog’s overall wellbeing. It is home to trillions of microorganisms that exist together as a complex ecosystem, helping to support digestion, nutrient production, the intestinal barrier and immune function. When this microbial community is healthy and diverse, beneficial bacteria help maintain a stable gut environment. They compete with potentially harmful bacteria for nutrients and space, produce beneficial compounds and help prevent less desirable microorganisms from becoming dominant.
However, many factors can disturb this delicate ecosystem. Poor diet, stress and anxiety, illness, surgery, changes in routine, antibiotics and certain other medications can all influence the composition of the gut microbiome. When the microbial community becomes significantly disrupted, a state known as dysbiosis, potentially harmful or opportunistic microorganisms may have greater opportunity to flourish while populations of beneficial bacteria may decline.
This imbalance can affect normal digestive function and may be associated with symptoms such as diarrhoea or constipation, loose or inconsistent stools, excessive gas and bloating. Changes within the gut microbiome can also influence the intestinal barrier and immune system, which is why gut health has implications that extend well beyond digestion.
This is where probiotics can play a useful role. By providing specific beneficial microorganisms, probiotics can help support microbial balance and a healthy intestinal environment. Alongside an appropriate diet, prebiotics and other lifestyle factors, they can form part of a wider approach to maintaining a healthy and resilient gut microbiome.
So, how does supporting the microbiome benefit your dog? Let’s take a closer look at some of the important roles it plays throughout the body.
How Probiotics and a Healthy Gut Support Immune Health
Did you know that around 70% of your dog’s immune system is associated with the gut? The gut microbiome, intestinal barrier and immune system work closely together, helping beneficial microorganisms to thrive while providing an important line of defence against potentially harmful bacteria, toxins and other unwanted substances.
The digestive tract is lined with a protective mucosal barrier and contains specialised immune tissue known as GALT (gut-associated lymphoid tissue). This contains immune cells that continually interact with both the microbiome and substances passing through the digestive tract, helping the immune system distinguish between what is harmless and what may pose a threat.
Beneficial gut bacteria also play an important role in this relationship. When certain bacteria ferment dietary fibres, they produce compounds known as short-chain fatty acids (SCFAs), including acetate, propionate and butyrate. These provide fuel for cells within the colon and help maintain an environment that supports beneficial bacteria while discouraging the overgrowth of potentially harmful microorganisms.
SCFAs, particularly butyrate, also help support the integrity of the intestinal lining and its protective mucus layer. A strong intestinal barrier is important because it helps control what passes from the digestive tract into the rest of the body.
The microbiome and the compounds produced by its bacteria also communicate with immune cells, helping to regulate and support a balanced immune response.
When beneficial bacteria and microbial diversity are reduced, this delicate balance can be disrupted, potentially allowing less desirable microorganisms to flourish. Supporting a healthy and diverse gut microbiome through appropriate diet, prebiotics and probiotics can therefore form an important part of supporting your dog’s digestive and immune health.
Supporting Digestion and Nutrient Absorption
The beneficial bacteria within your dog’s gut play an important role in digestion. These friendly microbes help ferment dietary fibres and other carbohydrates that your dog cannot completely digest on their own.
During this fermentation process, gut bacteria produce beneficial compounds known as short-chain fatty acids (SCFAs), including acetate, propionate and butyrate. These compounds have several important roles within the gut, with butyrate in particular providing an important source of energy for the cells lining the colon and helping to maintain a healthy intestinal environment.
The gut microbiome also influences how nutrients are broken down and made available for absorption. In addition, certain gut bacteria are involved in the production of vitamins, including some B vitamins, contributing to the many ways in which a healthy microbiome supports your dog’s overall health and wellbeing.
Supporting Cardiovascular Health
The benefits of a healthy gut extend far beyond digestion. Researchers are now exploring the gut-heart axis; the two-way relationship between the gut microbiome and cardiovascular health. A balanced gut microbiome helps regulate inflammation, immune function and metabolism, all of which play an important role in maintaining a healthy heart.
When the balance of beneficial bacteria is disrupted (known as dysbiosis), harmful bacteria and their by-products can pass through the gut lining into the bloodstream. This may trigger chronic, low-grade inflammation, placing additional stress on the body, including the cardiovascular system. Some beneficial bacteria also produce short-chain fatty acids (SCFAs), compounds that help maintain the integrity of the gut lining and support healthy blood vessel function.
Although research into the gut-heart connection in dogs is still developing, maintaining a healthy microbiome with a balanced diet and appropriate probiotic support may benefit not only digestive health, but also immune function and long-term cardiovascular wellbeing, particularly in older pets.
Supporting Urinary Tract Health
The urinary tract has its own community of microorganisms, known as the urinary microbiome, and research is increasingly exploring how microbial balance may influence urinary health. The gut microbiome may also play an indirect role. By supporting the intestinal barrier and normal immune function, a healthy gut microbial community can contribute to the body's natural defences against potentially harmful microorganisms.
Certain probiotic strains are also being investigated for their potential role in supporting a healthy urinary microbiome and helping to discourage the growth or colonisation of undesirable bacteria. However, this is an emerging area of research, particularly in dogs, and the benefits are likely to be strain-specific. Probiotics may therefore form part of a broader approach to supporting urinary tract health, alongside good hydration, an appropriate diet and regular opportunities to urinate.
Supporting Detoxification and Improved Elimination
When we think about detoxification, we often think of the liver and kidneys. However, the gut also plays an important role. A healthy digestive system helps process waste products, supports the body's natural elimination pathways and acts as a barrier, preventing unwanted substances from passing into the bloodstream.
This is where probiotics can make a difference. By helping to maintain a healthy balance of beneficial bacteria, probiotics support the integrity of the gut lining and encourage a diverse, resilient microbiome. A well-balanced microbiome can help break down dietary compounds, produce beneficial metabolites such as short-chain fatty acids, and support normal bowel function; all of which contribute to the body's natural detoxification processes.
Some probiotic bacteria have also been shown in laboratory and animal studies to bind certain environmental toxins and heavy metals within the gut, reducing their absorption and helping them to be eliminated in the faeces. While this area of research is promising, it is still developing, and probiotics should be viewed as supporting the body's own detoxification systems rather than acting as a detox treatment in their own right.
It's also worth remembering that probiotics work best as part of a wider approach to digestive health. A nutritious, varied diet, adequate protein, sufficient fibre, good hydration and, where appropriate, digestive enzymes all help to support healthy digestion and the body's natural detoxification pathways.
Some probiotic strains appear to be particularly beneficial for supporting the body's natural detoxification processes. Species such as Lactobacillus plantarum, L. rhamnosus and Bifidobacterium longum have been studied for their ability to support gut barrier function, maintain microbial balance and, in laboratory studies, bind certain undesirable compounds within the gut. Increasingly, probiotic formulations also include humic and fulvic acids. While these aren't probiotics themselves, they may help create a healthier gut environment, encourage microbial diversity and support the body's natural elimination pathways. Although research is promising, probiotics and humic substances are best viewed as supporting the body's own detoxification systems rather than providing a detox treatment.
Supporting Mood and Behaviour
The gut and brain are closely connected through what is often referred to as the gut-brain axis. Research shows that the gut microbiome communicates directly with the nervous system and can influence your dog’s mood, behaviour, and stress responses. Beneficial gut bacteria produce neurotransmitters; chemical messengers that help regulate communication between nerve cells. This means that gut health may play a role not only in digestion and immunity, but also in emotional wellbeing and behaviour.
Supporting Skin Health
Although the majority of the microbiome lives within the gut, beneficial bacteria are also naturally found on your dog’s skin, in their ears, on the surface of the eye and surrounding tissues, and other areas of the body. The skin microbiome forms an important protective barrier that helps defend against harmful pathogens and supports healthy skin function. Different areas of your dog’s skin are home to different microbial communities and maintaining balance between “good” and “bad” bacteria is essential. When this balance becomes disrupted, skin problems such as itching, irritation, and skin issues may occur. Research also suggests that dogs with allergies often have lower microbial diversity within their gut microbiome compared to healthy dogs, further highlighting the strong connection between gut and skin health.
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Supporting Gut Health in Older Dogs
As dogs age, changes can occur within the gut microbiome, including shifts in the populations and diversity of beneficial bacteria. Alongside other age-related changes, this may influence digestive function, nutrient utilisation and the health of the intestinal barrier. Ageing is also associated with an increase in chronic, low-grade inflammation, sometimes referred to as “inflammaging”. Because the gut microbiome interacts closely with the immune system and intestinal barrier, maintaining a healthy and diverse microbial community may be particularly important as dogs grow older.
The influence of the gut also extends beyond digestion. Through its interactions with the immune system, metabolism and the gut-brain axis, the microbiome has the potential to influence many aspects of health. Supporting the gut through a balanced diet, appropriate prebiotics and probiotics, and other microbiome-supporting nutrients can therefore form part of a wider approach to healthy ageing.
Fibre is particularly valuable for senior dogs. Soluble and fermentable fibres provide nourishment for beneficial gut bacteria, while insoluble fibre adds bulk to the stool and helps support regular bowel movements. Including a variety of appropriate fibre sources can help support both the microbiome and healthy digestion.
Hydration is equally important. Older dogs may be more susceptible to inadequate fluid intake, and poor hydration can contribute to harder stools and constipation. Providing constant access to fresh water, and adding moisture to the diet where appropriate, can help support normal digestive function.
By supporting a healthy gut microbiome as your dog ages, you are not only supporting digestion but also the many wider body systems with which the gut interacts – making gut health an important consideration throughout the senior years.
Supporting Dental Health
Your dog’s mouth is home to billions of bacteria and hundreds of different microbial species, making the oral microbiome the second largest microbiome in the body after the gut. Just like the gut, the mouth relies on a healthy balance between beneficial and potentially “bad” bacteria.
So, what are the Best Probiotic Strains for Dogs?
Not all probiotics are the same, and different strains of beneficial bacteria can support different aspects of your dog’s health. The most researched probiotics for dogs generally fall into three main categories: lactic acid bacteria, probiotic yeast, and spore-forming (soil-based) probiotics. Each group offers unique benefits for digestion, immunity, skin health, mood, and overall wellbeing.
Lactic Acid Probiotics
Lactic acid bacteria are among the most commonly used probiotics for dogs and include strains / species from the Lactobacillus, Bifidobacterium, some Enterococcus species and Streptococcus families. These are derived primarily from fermented dairy products. These beneficial bacteria help maintain balance within the gut by producing lactic acid, which creates an environment that discourages the growth of harmful microbes. Many of these strains have been shown to support digestive health, improve stool quality, reduce diarrhoea, and strengthen the immune system.
Certain strains, such as Lactobacillus acidophilus, help increase beneficial bacteria in the gut, whilst others, including the hardy strains of Lactobacillus plantarum and Lactobacillus rhamnosus may help support dogs with irritable bowel conditions and antibiotic-related digestive upset. Some strains also influence the gut-brain axis, the communication pathway between the gut and nervous system. For example, Bifidobacterium longum and Lactobacillus casei have been linked to supporting calmer behaviour and reducing signs of stress and anxiety in dogs. Also low levels of Lactobacillus rhamnosus have been linked to anxiety in dogs.
Probiotic Yeast
Saccharomyces boulardii is a beneficial, non-colonising yeast that acts as a probiotic and unlike many bacterial probiotics, this beneficial yeast is naturally resistant to antibiotics, making it especially useful for dogs taking antibiotic medication. Saccharomyces boulardii can help support a dog’s gut microbiome, digestive health, and immune function. It may help reduce diarrhoea, and as stated above, support recovery during antibiotic use, and promote a healthier balance of beneficial gut microbes.
Spore-Forming Probiotics
Spore-forming probiotics, often referred to as soil-based probiotics as they are highly resilient bacteria found in soil and water, include strains from the Bacillus family. These probiotics are unique because they form a protective outer shell that helps them survive heat, stomach acid, and antibiotics more effectively than many traditional probiotic strains. Strains such as Bacillus coagulans, Bacillus subtilis, and Bacillus indicus are known for supporting digestive health and strengthening immune function. Some also help produce important nutrients, including B vitamins and vitamin K2, whilst others provide antioxidant support.
Because spore-forming probiotics and probiotic yeasts are not dairy-based, they may also be a better choice for dogs with food sensitivities or dairy allergies.
So How Do You Choose the Right Probiotic For Your Dog?
Different probiotic strains provide different benefits, which is why selecting the right probiotic can depend on your dog’s individual needs. Some strains are better suited for digestive issues such as diarrhoea or IBS, whilst others may support skin health, immunity, stress, allergies, or recovery after antibiotics.
Here is a checklist to consider:-
- Look for a probiotic that is specifies specific. While some bacterial strains used in human probiotics may also be suitable for dogs, the canine gut microbiome and digestive environment differ from our own. Pet-specific probiotics are formulated with bacterial species and strains selected for their suitability and potential benefits in dogs, making them a more appropriate choice for targeted digestive support.
- Look for a product that clearly identifies the strains it contains together with the number of CFUs.
- Look for a high-quality probiotic supplement containing a variety of well-researched strains can help support a balanced microbiome and contribute to your dog’s long-term health and wellbeing. Quality probiotics will list the strains of bacteria on the label.
- Look for a high CFU (colony-forming units) to ensure that enough live bacteria reach your dog’s gut and ensure this is stated on the label to help you choose the right probiotic for your pet’s specific needs.
- The most appropriate probiotic will depend on your dog’s individual needs, as different probiotic species and strains have different properties. Think do you want an “everyday” probiotic or one that is more targeting for a specific issue.
• Saccharomyces boulardii and spore-forming Bacillus species are particularly resilient and may be useful when additional digestive support is required
• Traditional lactic acid bacteria such as Lactobacillus species are commonly used to support microbial balance and digestive health.
• Certain probiotic strains are also being studied for their potential influence on immune, skin and allergy-related responses, such as soil-based probiotics like Bacillus coagulans. - A combination of prebiotics and probiotics together will enhance the effectiveness of the probiotics
- Probiotics are available in power format, capsules, pastes and chews – so choose which format works best for you. Powders however are likely to have the highest CFU / more strains.
- Look to see what fillers, sugars and artificial ingredients have been added as these need to be avoided.
- Consider rotating between different probiotics, so your pet gets the benefits of the different strains. You may do this by using up a full tub before moving to a different type; or, do a month of one, then switch to a different type. Please see how blog on how best to rotate probiotics.
How to Give Probiotics to Your Dog
Probiotics can generally be given daily and, where appropriate, used long term. How long your dog needs them will depend on why you are using them. Some dogs may benefit from short-term support during periods of digestive upset, stress, dietary change or following medication, while others may use probiotics as part of their longer-term gut health routine.
Always follow the manufacturer's recommended serving guidelines, as the appropriate amount will vary according to the product, probiotic strains and your dog's size.
Probiotics are generally well tolerated, but some dogs can initially experience increased gas, bloating or changes in their stools as their digestive system adjusts. These effects are usually mild and temporary as your dog’s system adjusts.
If your dog has a sensitive digestive system, introducing the probiotic gradually and at a reduced amount, may also help their digestive systems to adjust. If symptoms persist it may mean that a particular probiotic strain, formulation or dose may not be suited to your dog, so stop the supplement. Every pet’s microbiome is unique. A reaction to one probiotic does not necessarily mean your pet won't tolerate another, as different products contain different strains and strengths. Please consult a Holistic Vet. Dogs with existing gastrointestinal disease, compromised immune function or other significant health conditions should ideally have probiotics introduced under veterinary guidance.
For healthy dogs, an appropriate probiotic can often be used on an ongoing basis. However, this doesn't necessarily mean that every dog needs to take a probiotic indefinitely.
Diet, fibre intake, prebiotics and overall dietary diversity all help support the dog's resident gut microbiome. Probiotics are best viewed as one part of a wider approach to gut health, rather than a replacement for good nutrition.
If you are using a probiotic to address a particular digestive problem, it is worth periodically reviewing whether your dog still needs it and whether the product continues to be appropriate.
