Guide to canine intestinal health and the importance of the microbiome

A dog's gut microbiota does not become balanced overnight – especially in a puppy, the gut undergoes major changes in the early stage of life. A puppy is essentially born sterile, but it begins collecting bacteria from its environment immediately after birth. An important first step is the mother's colostrum (first milk), which contains both antibodies and beneficial bacteria. During nursing, the mother's milk and the lactic acid bacteria obtained from it help colonize the puppy's gut with beneficial microbes. According to studies, the guts of nursed puppies contain abundant groups of bacteria such as Firmicutes, Bacteroidetes, and Actinobacteria, which have been shown to promote the puppy's digestion and the development of the immune system[7]. This means that the nutrients and friendly bacteria in the mother's milk create the foundation for the healthy development of the puppy's gut microbiota.

When a puppy is weaned from its mother and moves on to solid food, the gut microbiome continues to develop. During the early stages of development, the diversity of bacteria gradually increases and a diverse microbiome begins to stabilize[8]. By around adulthood, a dog's gut microbes usually reach an "adult level" – a kind of optimal balance in which different bacterial species are abundant and live in harmony with their host. This balance is influenced not only by diet but also by many other factors, such as the environment and individual differences. For example, each dog has its own distinctive microbiota, and even the breed and genetics affect what kind of bacterial population develops in the gut[9][10].

It is worth noting that with age the composition of the gut microbiota may change again. In older dogs, the diversity of gut bacteria may begin to decline, and certain beneficial bacteria may decrease[8]. In one study, it was observed that in older dogs the proportion of health-promoting Firmicutes bacteria decreased in the gut, while the proportion of Proteobacteria group bacteria increased[7]. Excessive growth of Proteobacteria is often associated with intestinal imbalance and increased susceptibility to inflammation. Age-related changes can impair a dog’s digestion and immune defense, so special attention should be paid to the gut health of senior dogs. The good news is that with the right lifestyle choices—such as high-quality nutrition and, if needed, the help of prebiotics or probiotics—the diversity and health of an aging dog’s gut microbiota can also be supported.

In summary: a puppy’s gut microbiome needs time and beneficial influences to develop into a strong one. The mother provides the important bacteria and nutrients at the start of life, after which a diverse diet focused on quality and the avoidance of unnecessary disturbances (such as repeated antibiotic courses) help the young dog’s gut microbes stabilize. An adult dog’s gut is usually fairly stable, but its balance must also be nurtured—and if the dog is among those with a "sensitive stomach," even small everyday choices (diet, stress management) can make a big difference. In a senior dog, gut well-being becomes especially important, as immunity weakens with age and the gut may need extra support to stay healthy. Next, we will take a closer look at the gut microbiome: what it means and why so much is said about it when discussing dogs’ health.

The intestinal microbiome refers to all those microbes – bacteria, fungi, yeasts, and viruses – that live in a dog’s intestines in symbiosis with their host[3]. You can imagine it as a vast, invisible ecosystem inside your pet. In a healthy intestine, this ecosystem is highly diverse: hundreds of species and billions of cells, each with its own small role. In general, the bacterial population in a dog’s intestine belongs to the same major groups as in humans: Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and Proteobacteria are typical major phyla of intestinal bacteria[11]. In a balanced microbiome, beneficial bacteria keep harmful ones in check – they essentially compete for living space so that the “bad bugs” do not gain too much of a foothold.

But why should a dog owner care about intestinal microbes? Here are some key reasons:

• Digestion and absorption of nutrients: Beneficial bacteria help break down nutrients such as fiber, which the dog’s own enzymes cannot fully digest. As the bacteria break down fiber, short-chain fatty acids (such as butyrate) are produced, which are the primary energy source for intestinal cells and at the same time protect the intestinal mucosa from inflammation[12][13]. Intestinal microbes also participate in the production of certain vitamins (e.g. vitamins K and B)[3]. Without a healthy microbiota, a dog may therefore not be able to utilize all that it needs from its food.
• Immune defense: As noted, the majority of a dog’s immune cells are located in the gut. Gut microbes train the immune system to distinguish harmful pathogens from harmless substances. A good microbial balance helps keep the intestinal wall strong and intact as a protective barrier. A balanced microbiome prevents harmful bacteria from settling in – beneficial microbes effectively take away their space and food, and even produce acids and other compounds that make the environment unfavorable for germs[14]. If the gut microbiota becomes imbalanced (dysbiosis), the number of harmful bacteria can increase too much, resulting in an overreaction of the immune system or inflammatory conditions[14]. For example, intestinal inflammation, food allergies, and even autoimmune diseases have been linked to an unhealthy microbial balance.
• Metabolism and weight management: Gut bacteria affect how efficiently a dog utilizes the calories in its food. Some microbes can enhance the extraction of energy from food – which may promote weight gain – while others consume energy and produce metabolic byproducts that increase the feeling of fullness. Studies have found links between a certain type of microbiota and obesity: for example, a specific bacterial ratio associated with dysbiosis (Firmicutes/Bacteroidetes) may predispose a dog to weight gain[15]. On the other hand, a diverse microbiota that ferments fiber produces plenty of beneficial fatty acids, which reduce inflammation and can support healthy metabolism[13]. In practice, good gut health can help keep a dog at its ideal weight when nutrient absorption and energy expenditure remain balanced.
• Mood and behavior: Dog owners may be surprised that the gut is also connected to the brain. A dog's gut and brain communicate through the nervous system (especially the vagus nerve) and various neurotransmitters[16]. Beneficial gut bacteria produce, among other things, serotonin, GABA, and other neurotransmitters, which can affect a dog's stress levels and mood[16]. In humans, the connection between the gut and psychological well-being has been recognized, and now studies suggest a similar phenomenon in dogs as well[17][18]. For example, some studies have found abnormal bacterial strains in anxious or aggressive dogs compared with more easygoing companions[5]. Although the research is still in its early stages, it can be said that a calm gut promotes a calm mind – and vice versa, chronic stress may manifest as stomach upset in dogs.

In summary: The intestinal microbiome is a vital part of a dog's health. It affects immunity, nutrient absorption, metabolism, and even a dog's brain. That is why it is important to take care of the balance of the microbiota. When the gut is healthy, the dog has more energy, gets sick less often, and recovers faster from exertion – and may even be a happier companion in everyday life. Next, we will examine the most common problems that can upset gut well-being, as well as how to recognize and act in these situations.

A dog's digestive system can be disturbed by many factors. Most dog owners will at some point encounter a situation where the dog's stomach is upset – most commonly in the form of diarrhea or loose stools. Occasional vomiting, flatulence, or loss of appetite may also suggest that the stomach is not entirely well. Below, we go through a few common intestinal problems, their underlying causes, and when it is necessary to be concerned.

Antibiotics are sometimes necessary, for example to treat an infection, but they can have an unpleasant side effect: they do not distinguish between "bad" bacteria and "good" bacteria. Thus, an antibiotic course may inadvertently also kill beneficial gut bacteria and disturb the balance of the microbiome. For the owner, this may show up as a dog having a loose stomach during or after antibiotics. Some dogs tolerate antibiotics without problems, while others get diarrhea or loss of appetite during the course.

Studies have shown that antibiotic treatment can significantly alter the composition of a dog’s intestinal microbiota – in a short time, the number of beneficial bacteria decreases and some more resistant strains (or yeasts) may take over[20]. Such dysbiosis can predispose to other health problems because the defense mechanisms of the intestines weaken. For example, after antibiotics a dog may be more susceptible to recurrent diarrhea or intestinal inflammation while the normal bacterial population is still recovering.

How can you support your dog’s gut during an antibiotic course? Prevention is the key word: unnecessary antibiotic courses should be avoided – use them only by a veterinarian’s prescription, for the correct purpose, and follow the instructions until the entire course is completed. Sometimes there are alternatives for ailments (for example, probiotics or supportive treatments for milder intestinal inflammations), but these decisions always belong to the veterinarian. When an antibiotic is indicated, the intestinal microbes can be supported with, for example, lactic acid bacteria (probiotics). There is research evidence that certain probiotic strains may shorten the duration of antibiotic-associated diarrhea and help restore the balance of the microbiota more quickly. Ask your veterinarian for a suitable product – probiotics designed for dogs are generally recommended during the course and for a few weeks afterward. Prebiotics (dietary fiber that feeds beneficial bacteria) may also be useful during recovery; a high-fiber, easily digestible diet helps beneficial microbes grow back. However, remember that every dog is an individual: observe how your dog responds, and report to the veterinarian if you notice significant side effects. If necessary, another supportive treatment or medication can be substituted alongside the antibiotic if the intestines do not seem to tolerate the medication.

On the positive side, the gut microbiome is usually quite resilient: it is capable of recovering over time. The recovery of beneficial bacteria can be deliberately supported: there are dog foods with added prebiotics (such as FOS, MOS or beet pulp) to help restore balance, and sometimes a veterinarian may recommend synbiotic products (a combination of prebiotic and probiotic). A scientific review states that restoring the beneficial bacterial population after antibiotics is essential for intestinal health – so after the course, make sure your dog receives gut-friendly nutrition and a calm recovery period[21]. Avoid unnecessary stress immediately after the antibiotic course (let the dog rest, keep a familiar daily routine), as stress can further worsen dysbiosis[21].

Some dogs seem to react sensitively even to the smallest changes – they can be called sensitive-stomached. A dog with a sensitive stomach may repeatedly have loose stools or occasional vomiting without any single clear cause being found. Typically, these are dogs that may have, for example, a mild gastrointestinal hypersensitivity to certain foods or whose intestines react strongly to stress. For example, travel or new food may cause stomach upset. With a dog with a sensitive stomach, the owner often learns the hard way to avoid certain ingredients or situations that are known to cause problems.

What can cause a sensitive stomach? One common cause is food intolerance or allergy. In dogs, common sensitivities are caused by proteins such as beef, chicken, dairy products, wheat, or soy. If a dog has such a sensitivity, its intestines may become mildly inflamed each time it is exposed to the substance in question, which appears as stomach symptoms. Another possible underlying cause is mild inflammatory bowel disease (IBD/CIE), in which the intestinal immune system is overactive and causes chronic inflammation; there are many causes for this (genetic predisposition, immunological abnormality, imbalance of the microbiota), and it requires a veterinary diagnosis. IBS (irritable bowel syndrome) is a term sometimes used to describe a functional disorder in which no clear physical cause is found, but stress and diet affect the symptoms. A sensitive stomach can therefore be a dog's "trait" – a bit like in some people – in which the dog remains symptom-free with the right diet and routines, but deviations can quickly cause symptoms.

How can a sensitive stomach be helped? First, regularity and consistency are your friends. Keep the dog's diet as simple and high-quality as possible: choose a highly digestible complete diet, avoid frequent changes of brand or protein source, and do not feed large amounts of treats that are hard on the stomach (such as very fatty meats or milk, if the dog does not tolerate lactose). Many dogs with sensitive stomachs benefit from fiber supplementation, which binds water in the intestines and balances stool consistency – you can ask a veterinarian about the use of psyllium fiber or other soluble fiber. Prebiotics (such as inulin, FOS) in food can feed beneficial gut microbes and strengthen the condition of the intestinal mucosa[22]. Probiotics may also be helpful when used continuously to support intestinal defenses; certain probiotic preparations are designed for long-term use, but these should also be discussed with a veterinarian so that the correct strain and dosage are chosen. Stress management is important for a dog with a sensitive stomach – try to keep daily routines as consistent as possible, provide the dog with a safe place and peace to rest, and accustom it to changes gradually. For example, if you know you will be traveling, you can accustom the dog in advance to being in the car with short rides and pack its familiar food along with, for example, a remedy that helps with motion sickness, if such a thing is useful.

It is also important to recognize when chronic ailments require veterinary examinations. If a dog has continuously recurring episodes of diarrhea, clearly loses weight, has blood in the stool, or has abdominal pain, one must not assume it is "just a sensitive stomach". In that case, investigations should be carried out – blood tests, stool samples for parasites, possibly food trials to confirm allergies, and in some cases endoscopy – so that any diseases can be treated. Treatment of chronic intestinal problems often includes dietary tailoring (e.g., an elimination diet for an allergic dog or a highly hydrolyzed special food for an IBD dog) as well as medication or supplements as needed.

In summary: A sensitive stomach requires attentiveness and effort from the owner, but with the right measures a dog can live a completely normal, happy life. Identify your dog’s sensitivities, avoid them as much as possible, and support gut health proactively with quality nutrition and good bacteria. Remember that help is available – do not hesitate to turn to a veterinarian if you feel you cannot balance your dog’s stomach on your own. Together you can find solutions, whether it is a special diet or another treatment method that no longer lets a sensitive tummy interfere with life.

Diet is perhaps the single most powerful factor that shapes the composition of a dog’s gut microbes on a daily basis. What a dog eats is also food for the intestinal bacteria – different nutrients feed different microbes. That is why it is not irrelevant what is put in the bowl. Broadly speaking, the amounts of protein, fat, and fiber in food directly affect which bacteria thrive in a dog’s gut[23].

Studies have shown that a high-protein diet (for example, a diet based purely on meat or one that is very meat-rich) favours certain groups of bacteria. In dogs that eat a lot of meat, increased levels of Fusobacteria bacteria and some protein-degrading bacteria have been observed[24]. They participate in amino acid fermentation and can produce metabolic by-products such as butyrate, which also has beneficial effects (butyrate suppresses inflammation in the intestine)[12]. However, an overly one-sided, extremely high-protein diet can leave beneficial fibre-degrading bacteria "without fuel" – if a dog gets no carbohydrates or fibre at all, for example bacteria of the Bifidobacterium and Prevotella genera are reduced. Fibre (and other prebiotic carbohydrates) is therefore invaluable for intestinal microbes: it is not absorbed in the dog's small intestine, but reaches the large intestine to be used by microbes. When beneficial microbes ferment fibre, short-chain fatty acids (SCFA, such as acetate, propionate, butyrate) are formed, which lower the intestinal pH, inhibit the growth of harmful bacteria and nourish the cells of the intestinal wall[25][12]. According to studies, a high-fibre diet is associated with a higher number of beneficial bacteria, including an increase in bifidobacteria and bacteria of the Faecalibacterium genus[22]. For example, inulin and fructooligosaccharides (FOS) are prebiotic fibres that have been shown to increase the proportion of beneficial microbes and promote butyrate production in the dog's intestine[22]. Certain functional sources of fibre, such as potato fibre, have also been shown to improve intestinal conditions: when fibre from potatoes was added to the food, the amount of Firmicutes bacteria increased and Fusobacteria bacteria decreased, which indicates a favourable change in the microbiota[26].

The proportion of fat in the diet also affects microbes. Very fatty food can, in some dogs, cause looser stools (fat is digested less well) and alter the composition of the microbiota toward a less acidic intestinal environment, where some harmful bacteria thrive. On the other hand, healthy fats, such as omega-3 fatty acids, can be beneficial: there is evidence that omega-3s reduce harmful bacteria (such as bacteria producing the inflammatory LPS endotoxin) and support the growth of beneficial bifidobacteria[27]. In other words, the quality of the fat is essential—EPA and DHA obtained from fish oil can protect the intestines, whereas a high intake of saturated fat may, if excessive, disturb the balance.

What about the form of the diet? There are various feeding philosophies on the market: industrial kibble, home cooking, raw feeding, plant-based feeding... All of these affect the microbiota. For example, dogs on a raw diet have been found to have greater bacterial diversity and, in particular, an increase in the Fusobacterium genus compared with dogs eating kibble[24]. In dogs eating dry food, for example, Prevotella bacteria may be more common, which is probably related to the higher carbohydrate content. It is interesting that a recent study found only small differences in the gut microbiota of healthy dogs when a completely plant-based (vegan) diet and a conventional meat-based diet were compared[28]. This indicates that the dog's gut microbiota is able to adapt to quite different nutrition without dramatic changes—provided that the diet is nutritionally complete. More important than the formal classification of the food is its nutritional content and how changes in the diet are implemented. Rapid changes can upset the balance: when the bacterial population is accustomed to one diet, a sudden change in nutrient composition can cause a temporary imbalance (and diarrhea). That is why new food should always be introduced gradually by mixing it with the old food over several days or weeks.

Overall, a good rule of thumb is to provide the dog with a varied and high-quality diet that contains protein, fat and fiber in suitable proportions. High-quality meat or fish as a protein source provides building blocks and palatability, while fiber (vegetables, root vegetables, whole grains or separate fiber supplements) feeds bacteria that are important for the gut. Individual differences must also be taken into account: one dog may do excellently on kibble containing grains, while another needs a grain-free diet to avoid skin or stomach problems. Tailor the diet to your dog and ask an expert if necessary (a veterinarian or someone specialized in pet nutrition) for advice on the feeding that is suitable for your dog – especially if your dog has health issues that the diet may affect.

Finally, it is worth emphasizing: what a dog does not eat is just as important as what it does eat. Keep trash and spoiled food scraps out of reach, do not let the dog gulp down large amounts of human food (many of these can cause stomach upset or be dangerous, such as chocolate, xylitol, onion, etc.), and be careful not to feed too many fatty treats. Balance and moderation are key. Gut microbes value consistency and nutrient richness – they thrive when they are continuously provided with good fiber and enough indigestible material to ferment, but they suffer if the diet consists of only one type of food or if the gut is repeatedly shocked by unsuitable ingredients.

In recent years, in pet health writing, one has increasingly come across the terms prebiotic, probiotic and postbiotic. They may sound very similar, but they refer to different things. All of them are connected to gut microbes: they are either the gut bacteria themselves or their nutrition and by-products. This chapter clearly explains what each of these terms means, what they are used for, and what benefits they may have for a dog's gut.

Prebiotics are substances that are not themselves food for the animal, but that feed beneficial gut microbes. In general, prebiotics are various fibers or carbohydrates that the dog’s digestive enzymes do not break down, but that end up in the large intestine to be digested by bacteria[29]. A prebiotic therefore works like fertilizer: it promotes the growth and activity of desirable bacteria in the intestine[29]. Examples of prebiotics are inulin, fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), resistant starch and pectin. Many of these occur naturally in vegetables and fruit – for example Jerusalem artichoke, chicory, banana, apple and carrot contain prebiotic fibers. For dogs, prebiotics are often given as part of a complete diet (many high-quality dog foods contain added FOS or beet pulp) or as separate fiber supplements.

What are the benefits of prebiotics? As noted earlier, prebiotics increase the number of beneficial bacteria (such as bifidobacteria) and the production of SCFA acids they produce[22]. This leads to a lower pH in the intestine, which prevents the growth of harmful bacteria. Prebiotics have been found to improve digestive efficiency, stool composition (e.g., reducing constipation or alleviating fluctuations toward overly loose stools) and even have effects that support immune defense through their microbe-modulating action[22]. In other words, by giving the gut “good food,” we support the dog’s health. Prebiotics are generally well tolerated, but in very large doses they can cause gas formation (because fermentation also produces gases). Therefore, if you add prebiotic fibers to your dog’s diet, do that gradually as well – so that you do not accidentally cause flatulence or stomach upset due to too abrupt a change.

Probiotics, in turn, are living microbes given to dogs to promote health. According to the definition of the World Health Organization (WHO), probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host[29]. In practice, probiotics include, for example, certain bacterial species or strains that are also found in the microbiome of a healthy intestine. Common bacterial genera used as probiotics include, among others, Lactobacillus (lactic acid bacteria), Bifidobacterium, and Enterococcus. Probiotic products developed for dogs may contain one or more carefully studied bacterial strains known to have beneficial effects in the dog's intestine.

How do probiotics work? Think of it as bringing reinforcements into the intestine for the army of beneficial microbes. When a dog is given probiotics, they settle at least temporarily in the intestine to compete with harmful bacteria. They can produce bacteria-killing substances (bacteriocins), displace pathogens by attaching to the intestinal surface before them, and they can also modulate the immune system in a calming direction. Probiotics have been found, for example, to shorten the duration of diarrhea in dogs, reduce antibiotic-induced intestinal disturbances, and possibly help with some skin problems and allergies (such as atopy) by balancing the immune response[30]. Some studies even suggest that probiotics could have a mild anxiety-relieving effect in dogs – probably through the gut–brain axis, as has also been observed in humans[31][32]. It is important to note that not all probiotics are the same: the effects are strain-specific. For example, Enterococcus faecium is a bacterium commonly used in dog probiotics, and certain strains have been shown to be safe and beneficial, for example in preventing diarrhea in puppies. By contrast, Lactobacillus rhamnosus GG is a well-known high-potency probiotic in humans, but its effects in dogs have been studied less.

Sources of probiotics: Several commercial probiotic products are available for dogs—pastes, capsules, powders, chewable tablets. Their composition and effectiveness vary. In general, the safest option is to use products recommended by veterinarians, where the bacterial strains and amounts are clearly stated. Probiotics can also be obtained from natural sources: some owners give their dog, for example, a little buttermilk, natural yogurt, or sauerkraut mixed with food. These contain lactic acid bacteria, but it is good to remember that not all dogs' stomachs tolerate dairy products (lactose intolerance is common in dogs). In addition, with natural products you do not know exactly which bacterial strains and how much the dog is getting. Therefore, for a particularly sensitive dog or in more serious conditions, it is advisable to use standardized products. Probiotics are often given as a course—for example, for 5–10 days in connection with diarrhea—but in some cases (such as a chronically sensitive stomach) a veterinarian may recommend longer use as well. They are quite safe, but very rarely in weak individuals there may theoretically be a risk that a live bacterium causes problems; for this reason, for example, probiotic treatment of very seriously ill or immunodeficient animals should always be discussed with a veterinarian.

Should probiotics be given to a healthy dog? Opinions differ on this. Some say that if a dog's stomach functions flawlessly, extra probiotics are of no benefit. Others believe that the modern environment and processed food impoverish the microbiota, so additional benefits are always welcome. Current research would seem to support the idea that probiotics may also be beneficial preventively: they may help maintain the healthy structure of the intestinal villi, improve nutrient absorption, and strengthen immunity[33][34]. In general, however, an otherwise healthy dog does not need continuous probiotic courses if it eats high-quality food and is doing well. From time to time—for example before a stressful situation (travel, competition) or when changing diet—probiotics may help keep the intestines calm.

Postbiotics are the newest addition to this trio. The term may be unfamiliar to many. Postbiotics refer to beneficial compounds produced by probiotics or products, or alternatively entire parts of microbial cells that have been inactivated but still have health effects[35][36]. In other words: when probiotics consume prebiotics, they produce postbiotics. A good example of a postbiotic is the previously mentioned butyrate (butyric acid), which is the end product of fiber fermentation by lactic acid bacteria. Butyrate has a strong anti-inflammatory effect and strengthens the intestinal wall[13]. Other postbiotics include, among others, lactic acid, bacteriocins (proteins produced by bacteria that inhibit competing bacteria), various enzymes, peptides, and cell wall components (such as teichoic acids). The essential point is that a postbiotic is not alive – it is either a part of a dead bacterium or a chemical compound secreted by a bacterium[37]. For this reason, postbiotics are often very stable: they can be added, for example, to pet foods or supplements without concern about the survival of live bacteria.

What benefits do postbiotics have? Although postbiotics are not alive, they can mimic the effects of probiotics in the body. For example, some postbiotics bind to the intestinal mucosa and stimulate the immune system in a controlled way – as if training it without the risk of infection. Several studies suggest that postbiotics can improve the composition of the gut microbiome, curb excessive inflammatory responses, reduce oxidative stress in cells, and help manage chronic diseases (such as skin problems or intestinal diseases)[30]. For example, in one study, giving dogs a preparation containing postbiotics reduced the symptoms of atopic dermatitis, which indicates an immune-mediated effect on skin health through the gut[30]. Postbiotics also have the potential to serve as an alternative to antibiotics in certain situations, because they can inhibit the growth of harmful bacteria without the risk that the bacteria will develop resistance to them[38].

Because postbiotics are a new concept, research on them is still ongoing. However, dog foods, for example, have begun to appear on the market that advertise a "postbiotic fermentation product" as an ingredient. This can mean, for example, dried fermented yeast or fermentation products of lactic acid bacteria that bring gut-beneficial compounds into the food. Postbiotics are promising, because they are safe (there are no live microbes, so there is no risk of infection), stable, and can offer the same benefits as probiotics. It is still worth remembering that they do not replace the live microbiome – rather, they are precision tools for managing specific issues.

Prebiotics, probiotics, and postbiotics can be seen as a continuum: they complement one another. Prebiotics are fuel that helps beneficial microbes (natural or administered as probiotics) grow and thrive. Thriving microbes, in turn, produce beneficial postbiotics, which provide health benefits for the intestine and for the dog as a whole[39]. It can be thought that if one wants to support a dog’s intestines, prebiotics and probiotics are often combined (a synbiotic): probiotics bring in more beneficial bacteria, and prebiotics feed both the old and the new beneficial bacteria. As a result, more postbiotics are produced, and the intestinal environment becomes favorable. In this sense, all three can be used to maintain intestinal health.

Practical example: Your dog has had a course of antibiotics, and you want to help its intestines recover. A veterinarian may suggest a synbiotic preparation that contains both probiotics (e.g., an Enterococcus faecium strain) and prebiotic (e.g., FOS fiber). You give this to the dog daily for a couple of weeks. The probiotics settle in the intestine and the prebiotic feeds them – they begin to produce postbiotics such as butyrate, which repairs the intestinal lining and reduces inflammation. In addition, probiotics temporarily prevent harmful bacteria from growing. As a result, the dog’s stool becomes firmer and bowel function normalizes more quickly than without supportive treatment[40]. Such "triple therapy" is becoming more common in both human and veterinary contexts, and it illustrates how important microbes and their food are for well-being.

In summary of these terms: - Prebiotic = a fiber or other compound that feeds beneficial bacteria (e.g., inulin). - Probiotic = a live beneficial bacterium given to support health (e.g., lactic acid bacterium). - Postbiotic = a product of beneficial bacteria or an inactivated bacterium that has a health effect (e.g., butyrate or heat-treated lactobacillus)[41].

These can be used separately or together for the benefit of your dog’s intestinal health. It is still always a good idea to discuss with an expert what your own dog may need – every dog is an individual, and unnecessary additions should not be given without reason. Next, we will provide some general practical tips with which you can support your dog’s intestinal well-being in everyday life.

Small everyday actions and choices can significantly affect the well-being of your dog’s gut microbiota. Below is a collection of tips and good practices that help keep the stomach content and the microbes in harmony. These tips benefit both a puppy’s and an adult dog’s intestines – and many of them are the same things that generally support a dog’s overall health.

• Provide high-quality, balanced nutrition: The basis of feeding should be a complete dog food from which the dog gets all the nutrients it needs. Choose a food that suits your dog’s age, size, and specific needs. High-quality food often also contains fiber beneficial to the intestines (such as beet pulp, flaxseed, or other prebiotics) naturally or added. Avoid diets that are very one-sided or that contain too many fillers – remember that variety (an appropriate balance of different nutrients) supports a diverse microbiome.
• Maintain a feeding routine, but avoid sudden changes: A dog’s intestines appreciate regularity. Feed your dog at roughly the same times every day and avoid constantly changing the brand of food without a good reason. If you change your dog’s food, accustom it to the new food gradually by mixing it with the old food over a 7–10 day transition period. This gives the intestinal bacteria time to adapt to the new food, and the balance will not be disrupted. In the case of a puppy, remember that from weaning onward it is important to proceed step by step with food – for a small stomach, too large changes can be a shock.
• Maintain hygiene, but let the dog be a dog: Microbes from the environment are part of the intestinal ecosystem. Let the dog sniff and explore its surroundings outdoors – this exposes it to a wide range of environmental microbes, which can even enrich its gut microbiota (for example, roaming in the forest and digging in the soil bring soil bacteria into the gut, which may support a diverse microbiota). On the other hand, prevent the dog from eating rubbish, carcasses, or other animals’ feces, which can introduce harmful bacteria or parasites. Balanced hygiene means that you do not keep the dog in a sterile bubble, but neither do you let it constantly gulp down everything it can get into its mouth. At home, wash the dog’s food bowl regularly and store food hygienically to avoid spoilage.
• Practice stress management: A dog’s mental state affects its stomach. Stress can alter intestinal motility and even the microbial flora (for example, stress hormones can reduce certain beneficial microbes in the gut). Therefore, try to maintain routine and security in the dog’s life. If a stressful event is expected (e.g. fireworks on New Year’s Eve or a veterinary visit), prepare the dog in advance: if necessary, use natural calming support products (such as pheromone diffusers) and provide extra security and familiar items (its own bed, toy) during the stressful period. Some dogs benefit from a course of probiotics before a stressful situation – studies have shown that probiotics may help dogs cope better with stress, for example during travel[21]. The most important thing is to identify the sources of stress and try to minimize unnecessary strain.
• Exercise and weight control: Regular exercise keeps the bowels moving as well. Daily walks and play help the digestive system function normally and prevent constipation. Excess weight has been shown to affect gut microbes – obese dogs may have a different microbiome composition than lean dogs, and obesity predisposes the body to, among other things, low-grade inflammation. By keeping your dog lean and in good muscle condition, you also support its intestinal health. However, remember to avoid overly strenuous exercise immediately after meals, especially in large breeds, because it can predispose them to gastric torsion and digestive disorders.
• Water, water, water: Make sure your dog always has fresh water available. Adequate hydration is vital for bowel function – water softens stool and helps dietary fiber swell and do its job. This is especially important in cases of diarrhea, because more fluid is lost than normal. If needed, you can flavor the water with e.g. a small splash of meat broth if the dog is not enthusiastic about drinking, or offer moistened food to ensure sufficient fluid intake.
• Protect against parasites: Intestinal parasites (such as roundworms, hookworms, and Giardia) can cause ongoing stomach problems and damage the intestinal microbiota. Follow your veterinarian's recommendations for regular deworming – especially puppies and dogs that meet many other dogs or hunt rodents in the wild should be examined and dewormed regularly. Pick up your dog's feces from the environment to reduce the spread of parasites. If your dog has prolonged diarrhea, the veterinarian will usually first rule out parasitic infections, for example with a stool sample test. So take care of this aspect as well, so that worms or protozoa do not lie hidden behind intestinal problems.
• Consider prebiotics and probiotics as part of daily life as needed: Not all dogs need to eat supplements, but in certain situations they can be beneficial. For example, if your dog is known to have a sensitive stomach, you can consult a veterinarian about using a continuous prebiotic or probiotic product as part of the diet. Some complete foods already contain added prebiotics (such as chicory root or mannan-oligosaccharides) to support the intestines daily. Fermented foods and treats have also entered the market, containing natural postbiotics – for example, fermented dog food or dog-friendly products made from sauerkraut. These can be beneficial, but remember always to introduce new things gradually. Also note that too much is too much: excessive fiber supplementation or too many different bacterial preparations at the same time can even disturb the intestines. One thing at a time, and observe the effects.
• Monitor your dog's stool and condition: Your dog's poop tells a great deal about the condition of its intestines. Ideally, the stool is formed, firm but not hard and crumbly, and brown. Learn to identify what is normal for your own dog. If you notice changes – looseness, mucus-filled stool, a very pale or black color, foul-smelling gas formation, difficulty defecating, etc. – pay attention to what may have changed (feeding, stress, etc.). Many intestinal problems are easier to resolve when they are detected early. The stomach does not become painful "suddenly without reason"; rather, there is often some underlying factor. Your dog's overall condition (alertness, appetite, drinking) together with the quality of the stool provide the full picture: if the poop is loose for a while but the dog is otherwise normal, you can keep observing; but if the loose stool continues and the dog seems unwell or lethargic, action is warranted.
• Do not hesitate to seek help: Although many stomach issues are mild, it is always better to ask a veterinarian for advice than to remain uncertain. There is now specialized expertise available for canine gut health: there are veterinarians specializing in internal medicine for dogs, professionals in nutritional counseling, and even tests that can analyze the composition of a dog's gut microbiota. If you are struggling with your dog's ongoing intestinal problems, professionals can help determine whether the underlying cause is, for example, intestinal inflammation, a lack of pancreatic enzymes, or some rarer issue, and draw up a treatment plan. Many intestinal problems can be brought under control by combining the right diet, any necessary medications (if, for example, the pancreas does not produce enzymes, enzyme powder is added to the food), and supplements that support the intestines. You are not alone in this matter – pets' digestive issues are among the top 3 reasons for veterinary visits, so help and information are widely available.

Even small actions can therefore affect the happiness of your dog's gut microbes. Remember that the cornerstones of gut wellbeing are high-quality nutrition, regularity, appropriate exercise, freedom from stress, and, when needed, targeted support (such as pre/probiotics). Next, we will move on to the guide's FAQ section, where you will find answers to frequently asked questions about a dog's intestines and microbiome.

The microbiome of a dog's intestines refers to all those microscopic organisms (such as bacteria, yeasts, protozoa) that live in the dog's digestive tract. They are most numerous in the large intestine, where they form a complex community. The microbiome lives in symbiosis with the dog – it helps, among other things, with digestion, vitamin production, and immune defense. A good microbiome balance (eubiosis) means that beneficial bacteria are dominant and keep potential pathogens in check. A disturbed microbiome (dysbiosis), on the other hand, means that the balance has been upset, for example a harmful bacterium has become more common or diversity has decreased, which can lead to health problems[1][6].

One of the most important signs of a healthy intestine is normal stool. A healthy dog’s stool is firm, formed, and easy to pick up; neither watery nor rock hard. The number of bowel movements is also characteristic for the dog (usually 1–3 times a day in an adult dog), and the rhythm is fairly regular. A dog’s overall well-being reflects the condition of the intestines: when the stomach is in good shape, the dog is energetic, eats with a good appetite, the coat shines, and the skin is healthy. Flatulence and burping should be fairly rare — constant foul-smelling gas may indicate food that is poorly digestible or an imbalance of bacteria. Weight management also works well: if the dog’s weight stays at its ideal level with the same amount of food, that suggests nutrients are being absorbed normally. A healthy intestine is usually not heard or seen in any special way in everyday life — it does its work in the background. You can think of it this way: when your dog’s stomach works like clockwork and you do not have to think about its stool or appetite all the time, the intestines are probably doing well!

Yes — occasional mild diarrhea or a one-time vomit is part of almost every dog’s life, just as humans can get a stomach bug or have some food "go through." For example, a small dietary change, too many treats, or a contaminant that got into the mouth outdoors can cause a single day of diarrhea that passes quickly. Likewise, dogs may sometimes vomit after eating too hastily (so-called regurgitation) or, for example, yellow foam on an empty stomach (bile secretion) — this can also be normal for some dogs from time to time. The important thing is to observe that after a temporary upset the dog returns to normal: diarrhea should settle within 1–2 days with home care, and vomiting should stop when the stomach is rested.

If loose stool or vomiting occurs frequently (e.g., weekly), or if it is accompanied by other symptoms such as weight loss, persistent loss of appetite, or abdominal pain, then the problem is no longer "normal" and should be examined more closely. In other words, isolated cases are usually harmless, but recurring symptoms require action. Puppies need more caution: a puppy’s immune system is weaker, and diarrhea can dehydrate them quickly, so one should be careful and, rather than risk waiting too long for help, it is better to visit the veterinarian once unnecessarily than to be late with treatment.

Whenever the dog’s symptoms are severe, prolonged, or the general condition worsens, it is advisable to contact a veterinarian. Here are some guidelines: - If the diarrhea is very severe or bloody, or if it is accompanied by persistent vomiting, you should go to the vet immediately (there is a risk of dehydration and possibly a serious underlying cause). - If the dog repeatedly vomits all the water it drinks or the food it has eaten, it needs help (a vomiting dog dehydrates and may be a sign of an obstruction, etc.). - High fever, weakness, seizures, clear abdominal pain (the dog tenses up, whines when touched, lies in an odd position) are warning signs – in relation to the intestines, they may indicate, for example, a foreign object in the intestine, pancreatitis, or another serious inflammation. - In the case of puppies and elderly dogs, I would go to the vet more readily, even for vomiting or diarrhea lasting one day, because their bodies dehydrate and weaken more quickly. - If the dog has chronic intestinal symptoms, such as ongoing looseness for weeks or recurring symptom episodes, it is advisable to book an examination. The most common cause of chronic diarrhea is a food allergy[42], but that too must be confirmed by ruling out other causes. - Whenever you are unsure, it is better to have it checked. Veterinarians would rather see a patient "unnecessarily" than have someone wait too long at home.

At the veterinarian’s, basic examinations can be performed (listening to the intestines, palpating the abdomen, possibly taking blood tests and stool samples). In acute cases, treatment often includes fluid therapy, anti-nausea medication, and, if needed, protective medication for the intestines – and of course treatment of the underlying cause (for example, antibiotics if it is a severe bacterial infection, or deworming if parasites are found).

Checklist: Take the dog to the vet if: bloody or very severe diarrhea, persistent vomiting, fluids cannot stay down, the dog seems unwell/tired, symptoms last more than 2 days without clear improvement, or whenever you suspect something more serious than normal. Better too early than too late!

It can. In dogs – as in humans – the gut and the nervous system are closely connected. When stressed, the body secretes stress hormones (such as cortisol and adrenaline), which can affect bowel function: intestinal movements may speed up (resulting in looser stool) or, conversely, some dogs may hold back from defecating when stressed and become constipated. A typical example is a dog that goes to a boarding kennel or an unfamiliar place and gets diarrhea from nervousness. Stress can also change the balance of gut microbes. In chronically stressed dogs, some studies have found a different microbiome composition – for example, a lack of beneficial bacteria and an increase in some bacteria that grow under stress[18]. As a result, long-term stress can predispose dogs to intestinal inflammation or worsen existing problems. In addition, a dog with stomach issues may become even more stressed, which is an unfortunate vicious circle.

In practice, many dog owners report that their dog has a "nervous stomach": for example, on show or competition days the dog defecates more often and more loosely. Or in thunderstorm weather and at fireworks, an anxious dog may tremble and then a loose pile may be found on the floor. These are very concrete examples of how mental state and physiology are connected.

It is important to note that not all dogs react to stress in their stomachs – individual differences are large. In any case, the connection between the gut and the brain is a scientifically established phenomenon, and it is called the gut–brain axis. The good news is that the effect also works in the other direction: if we support gut health (for example, with probiotics), we can alleviate the effects of stress. One study mentions that the use of probiotics combined with prebiotics helped stabilize the dogs’ gut microbiota in stressful situations, even though the stressor itself was present[21]. So yes, stress affects the stomach – but we can try to influence it either by reducing stress or by supporting the stomach, preferably both.

These three terms are easily confused. In summary: - Prebiotics are food for beneficial bacteria. Often fibers that nourish beneficial microbes living in the intestines and promote their growth[43]. Prebiotics are obtained from food (fiber in vegetables, grains) or as a supplement, and they improve intestinal conditions indirectly. - Probiotics are live beneficial bacteria. They are given orally and settle in the intestines to provide health benefits[43]. They compete with harmful microbes and support the immune system. Probiotics are found, for example, in lactic acid bacterial preparations. - Postbiotics are beneficial substances produced by beneficial bacteria or inactivated microbes. They are not alive, but they have health effects, such as anti-inflammatory or intestinal wall-protective effects[35][36]. An example is butyric acid or, for instance, fragments of the cell wall of a heat-treated probiotic. Postbiotics can be obtained from fermented products or separate preparations.

In simple terms: prebiotics feed probiotics, which produce postbiotics. It all aims to ensure that there are more beneficial bacteria in the gut (probiotics) and their beneficial effects (postbiotics) available.

If your dog is completely healthy, the digestive system functions excellently, and there are no specific risk factors, separate supplementary products are usually not needed. High-quality dog food usually provides enough fiber (prebiotic) to maintain a normal microbiota. A dog also naturally gets probiotics from the environment (for example, soil bacteria). Unnecessary supplementation may not be beneficial and may be a waste of money.

There are, however, situations in which prebiotics or probiotics can be beneficial even for a healthy dog: - When changing food (for example, when a puppy moves from the breeder to a new home, or a new food is introduced): a course of probiotics in advance and during the transition can help the intestines adapt. - When traveling or in another stressful situation as a preventive measure: probiotics can be given for a few days beforehand and throughout the stress period to support the gut, even if the dog is healthy (this is widely used, for example, for dogs traveling to show rings). - The dog tends to eat everything outdoors (for example, feces, carcasses): constant "germ exposure" can in some dogs lead to recurring loose-stool problems — in such cases, a daily prebiotic fiber supplement can help stabilize digestive function, and probiotics can be used in courses as support. - Senior dog: in older dogs, prebiotics can support a weakening microbiota, and probiotics can improve immunity.

So, for a healthy dog without symptoms, there is no automatic need to give gut supplements. Good food and a good life are sufficient. However, if you know that a change is coming or you want to ensure gut well-being in a certain situation, you can cautiously try a probiotic or extra fiber. Always observe your dog's reaction: if, for example, starting a probiotic worsens stool quality (rare, but there are individual differences), stop using it.

In moderation, yes, it can be given — but the effectiveness varies. Yogurt, buttermilk, and kefir contain lactic acid bacteria, which are probiotic for humans. For the stomach of some dogs, a small amount of plain yogurt per day is beneficial: it provides both probiotics and prebiotic lactose (which their intestinal bacteria can use if the dog tolerates lactose). NOTE: However, many adult dogs do not tolerate lactose, so dairy products can cause loose stools. For this reason, it is good to test cautiously: a teaspoon of yogurt in food and see whether symptoms appear. If not, the amount can be increased slightly. More suitable fermented dairy products for dogs are low-lactose or lactose-free versions (for example, low-lactose buttermilk). Kefir has sometimes been praised because it contains several beneficial bacterial strains; giving a small splash can provide beneficial microbes. However, remember that the probiotics in dairy products do not necessarily establish themselves permanently in the dog's intestines — they may provide temporary help, but they do not replace the dog's own strains.

Another option is to give the dog sauerkraut or kimchi in very small amounts, if it likes them (and if kimchi, then without onion/spices). The juice from sauerkraut contains lactic acid bacteria and fiber, so some people use it as a natural probiotic for dogs. Here too, a small dose is important: too much sauerkraut can cause flatulence.

As a general rule: yes, a dog can get lactic acid bacteria through food, but for the stomach it is often more reliable to use probiotics intended for dogs when a therapeutic effect is actually desired (for example, in connection with diarrhea). Yogurt can be given as a treat if the dog enjoys it and tolerates it, but it is not worth forcing dairy products on a dog "for health reasons" if it does not want them or if they do not suit it.

Numerous studies have been conducted on prebiotics and probiotics for dogs, and many of them point to benefits—provided that the right strains and conditions are used. For example, probiotics have been shown in studies to: - Shorten the duration of acute, mild diarrhea in dogs by about one day on average compared with placebo[44]. - Reduce diarrhea during an antibiotic course (in one experiment, an Enterococcus faecium probiotic reduced the incidence of antibiotic-associated diarrhea in puppies). - Improve stool quality in puppies and reduce diarrhea during puppyhood when added to food by the breeder. - Possibly relieve symptoms of some skin problems (there is evidence that certain probiotics reduce itching in atopic skin because they modulate the immune system)[30]. - Improve the integrity of the intestinal mucosa, for example in stressful situations (it has been shown in experimental animals that probiotics can reduce "leaky gut" under the influence of stress hormones).

There is evidence for prebiotics, for example: - Adding inulin and FOS to dog food increased the number of bifidobacteria and improved stool consistency[22]. - In dogs prone to hard stools, psyllium fiber (ispagula seed) added to the food softened the stool appropriately. - Prebiotics may improve mineral absorption (in humans and likely also in dogs, calcium absorption from the intestine is enhanced when fermentable fibers are available). - In some studies, prebiotics have reduced the concentrations of harmful metabolic products (e.g. ammonia) in the stool, in other words, made the intestinal environment "cleaner".

Postbiotics are a newer research area, but a few studies show that: - A postbiotic (e.g. the cell wall of fermented yeast) added to dog food reduced inflammatory markers in senior dogs and improved certain immune system indicators[45]. - A combination of postbiotics with prebiotics improved the amounts of Lactobacillus bacteria in older dogs and increased the production of beneficial fatty acids in the gut[46].

Overall, the science supports the view that yes, these are beneficial, but the effects are often modest, meaning relatively small and individual. They are not miracle cures that solve all problems, but they can be a valuable part of treatment or prevention. It is important to choose the right product and use it correctly. For example, if a dog has intestinal inflammation, a probiotic alone may not be enough to cure it, but it can support other treatments and speed recovery.

How clearly the benefit is noticed also depends on the baseline situation. A healthy dog may not visibly "change" at all after starting a probiotic - which is to be expected, because it did not have a problem to begin with. But a dog with a sensitive stomach may clearly gain a more stable gut with a probiotic. So anecdotes vary, and science gives the average: there is benefit when the product and the situation match.

Absolutely, there may be a connection. In recent years, it has been understood that in many skin problems and allergies, the gut microbiome also plays a role. A common issue in dogs, the skin inflammation predisposition known as atopy (allergic itching), is a disorder of the immune system. And because a large part of the immune system is in the gut, it is logical that intestinal balance also affects the condition of the skin. One study found that atopic dogs had fewer certain beneficial bacteria and more inflammation-promoting bacteria in their gut compared with healthy dogs. When these atopic dogs were given postbiotics and prebiotics, some inflammatory markers in the skin decreased[30]. Yeast infections on the skin or in the ears can also be linked to the gut: if an antibiotic or diet causes dysbiosis in the gut, it is thought to predispose to yeast overgrowth not only in the intestines but also on the skin, because the balance of immune defense is disturbed.

On the other hand, in dogs with severe food allergies, the gut often reacts first—vomiting or diarrhoea—but the skin may also show symptoms (itching, redness). When the condition of the gut is improved (for example, with a hypoallergenic diet, gut-protective agents, probiotics), skin symptoms often also ease. This holistic concept is called the "gut-skin axis" or the gut-skin axis.

Nor should coat condition be forgotten: the absorption of nutrients (such as fatty acids, zinc, biotin) requires a healthy gut. If the gut is in poor shape, deficiencies in vitamins and trace elements can show up in the skin and coat as roughness, flaking, or hair loss.

Overall, if your dog has chronic skin problems or allergies, it is also worth considering gut health. In the treatment of skin problems, fatty acid supplements are often used (which also affect the gut), and sometimes probiotics as well to support immunomodulation. Even if the actual problem is in the skin (e.g. an allergic reaction to pollen), a healthy gut microbiome supports the dog's overall well-being and can curb excessive immune reactions. So yes, gut and skin health are surprisingly closely linked.

The first step is to identify whether there is a need to improve something. If your dog is doing well, the gut microbiome is best maintained by keeping routines and feeding on track (see the tips in the previous chapter). If, however, you suspect that the dog's microbiome is not in optimal condition—for example, recurrent gastrointestinal symptoms, the dog has had many courses of antibiotics, or perhaps a rescue dog with a background of poor nutrition—you can take action:

1. Dietary improvement: Switch from possibly low-quality food to something more digestible and more nutrient-rich. Add fibre in moderation, for example by mixing a spoonful of cooked pumpkin or carrot purée into the food (if the dog likes it), or occasionally offer the dog a little steamed broccoli in pieces as a treat. Fibre is fuel for beneficial bacteria.
2. Prebiotic supplement: You can obtain a prebiotic powder from a pharmacy or veterinary clinic (e.g. a FOS-inulin mixture) and add it to the food according to the instructions. Start with a small dose and increase slowly so that the dog gets used to it. This helps feed beneficial microbes and increase their share.
3. Probiotic course: Give the dog a reliable probiotic preparation, for example for a 1–2 month course. Especially if there has been antibiotic use or prolonged diarrhea, probiotics help restore balance. Remember to choose a product that contains bacterial strains suitable for dogs and has been stored properly (so that the bacteria are alive).
4. Limit unnecessary medications and chemicals: For example, if the dog often receives antibiotics, discuss with the veterinarian whether they were necessary every time or whether there are alternatives. Likewise, frequent use of anti-inflammatory medication can disturb the gut—aim to use medicines only when needed and with protective medication if they irritate the stomach.
5. Let time pass and avoid rushing: Improving the microbiome does not happen in a day. When you make good changes, continue them consistently. Avoid making too many changes at once so that you know what works. For example, if you gave a probiotic and changed the food at the same time and the dog gets upset, you do not know which was the cause. One change at a time, one or two weeks of monitoring, then the next.
6. Diversify the environment: This may sound odd, but according to some studies, dogs living in the countryside or close to nature have a more diverse skin and gut microbiome than those living entirely in the city’s asphalt jungle. If possible, take the dog into the forest or to the edge of a field regularly to sniff and play. This exposes it to "good dirt microbes." Of course, make sure it has tick protection and does not eat anything dangerous—the goal is not to become ill, but simply to let nature do its work in the development of immunity.
7. Monitor and, if necessary, have tested: If you want to study this properly, some specialized laboratories offer microbiome analysis from a dog’s stool sample. It is not yet routine care and is not necessarily inexpensive, but it gives you an exact picture of which bacteria are found in the dog’s intestine and in what proportions. This allows you to target improvement measures—for example, if the analysis showed an overgrowth of proteobacteria, you would know that a very gentle diet and perhaps added prebiotics are needed. For most people, however, this is not necessary; the basics take you a long way.

Overall improvement is achieved by taking care of the basics: diet, exercise, low stress, and gut-friendly supplements if needed. The intestinal microbes will reward you indeed – you will probably see changes over time in the dog's stool (firmer, less odor), skin (less itching, better coat), and overall vitality.

The canine digestive system has both similarities to and differences from that of humans. The basic structure is similar (stomach, small intestine, large intestine), and both have a rich intestinal microbiota that affects health. In the intestines of both, mostly the same major groups of bacteria live (Firmicutes, Bacteroidetes, etc.)[11]. However, a major difference is that the dog is an omnivore whose digestion has evolved to process meat-based food. The dog's intestine is relatively shorter than a human's, and the stomach is much larger and more acidic – a dog can digest raw bones and bacteria-rich meat better than a human can. The pH of the dog's intestine is lower (more acidic), which kills bacteria in prey. The transit time is also faster: a dog's food passes through the intestines in about 12–30 hours, whereas in humans it can take 24–72 hours. This also affects the microbiome: in the dog's intestine, Fusobacterium bacteria, which break down proteins, are more common than in humans[47], whereas in humans, the extensive fermentation of fiber produces many bacteria from the Bacteroides and Prevotella genera, which dogs have somewhat less of. Dogs are also better able to utilize animal fats and proteins as energy sources; their pancreas produces abundant protease enzymes for breaking down meat.

At a practical level, this is seen, for example, in the fact that foods that are healthy for humans (such as a very fiber-rich bean stew) may be too difficult for a dog to digest and cause flatulence, because their gut is not as long and does not ferment all the fiber completely. On the other hand, a dog can eat raw meat without getting stomach illness, whereas for a human that could be a risk – thanks to a dog’s stomach acid and short intestine, bacteria do not have time to multiply to a harmful extent, if the food is intended for the dog’s own feeding use.

The role of the gut microbiome is probably very important in both species, but microbiome research in dogs is a younger field of science. One difference has been observed in immunological regulation: the microbes in dogs’ intestines strongly affect, for example, their skin diseases, whereas in humans the gut has a much greater influence on metabolic (metabolism) diseases. These differences may be due to both genetics and diet.

In short: A dog’s gut is designed from a somewhat different starting point than a human’s, but for the well-being of both a diverse microbiome is beneficial. Many health tips for humans also apply to dogs (fiber, fermented foods, stress management), but the dose and implementation must be adapted to suit the dog. In addition, there are many dog-specific differences – one should always identify the individual characteristics of one’s own pet, because some dogs can digest even a shoe while eating anything, and others get an upset stomach from just half a sausage.

In conclusion: A dog’s gut health and microbiome balance are an essential part of your pet’s well-being. So keep the gut as a friend – when you take care of food, routines, and love, your dog will thank you with a healthy, cheerful appearance and a lively wag of the tail. Taking care of the gut is both preventive healthcare and an everyday expression of love for your best friend. Onward to new adventures with healthy stomachs!

Sources:

[1][2]Tassu Foods blog: "The gut is your dog’s immune powerhouse", 23 Jan 2025 – Definition of the microbiome, the role of beneficial bacteria in digestion and immunity, the role of the immune system in the gut.

[3]Bonel-Ayuso et al. 2025 (MDPI Microorganisms): Effects of Postbiotic Administration on Canine Health – The composition of the canine microbiome and its effects on digestion, vitamin synthesis, immune response, and defense against pathogens.

[4]Kim et al. 2025 (BMC J. Animal Sci. & Biotech.): Understanding the diversity and roles of the canine gut microbiome – Health effects of microbes: the intestinal microbiome regulates digestion, immune response, energy expenditure, and even behavior.

[5]Pellowe et al. 2025 (Scientific Reports): Gut microbiota composition is related to anxiety and aggression in dogs – Research finding: the connection of certain bacteria with anxiety and aggression in dogs, for example the association of the genus Blautia with canine behavior.

[6]Kim et al. 2025 – A balanced microbiome (eubiosis) promotes health and metabolism, whereas a disturbed microbiome state (dysbiosis) has been linked to weight fluctuations, metabolic diseases, and behavioral changes.

[7]Kim et al. 2025 – Intestinal stage in puppies: the lactic acid bacteria in the mother’s milk increase the Firmicutes, Bacteroidetes, and Actinobacteria groups, which support the puppy’s digestion and immune development.

[8]Kim et al. 2025 – Effect of age on the microbiome: bacterial diversity increases in puppies and stabilizes in adulthood; in older dogs, diversity may decline, which may weaken digestion and immune defense.

[23]Kim et al. 2025 – Diet is the most significant factor affecting the microbiome; the protein and carbohydrate content of the diet shapes the composition of the intestinal microbiota.

[22]Kim et al. 2025 – Effect of prebiotics: FOS and inulin increased SCFA production and the numbers of beneficial bifidobacteria and bacteria of the genus Faecalibacterium in dogs.

[26]Kim et al. 2025 – Effect of fiber supplement (potato fiber): increased the proportion of Firmicutes bacteria and reduced bacteria in the Fusobacteria group, improving intestinal microbial balance.

[40]Kim et al. 2025 – Maintaining balance: optimizing the diet according to life stage (protein, fiber, carbohydrates), including probiotics and prebiotics in the diet is essential; they promote the growth of beneficial bacteria and the maintenance of eubiosis. Restoring beneficial microbes after antibiotics, minimizing stressors, and environmental stability also help maintain microbial balance.

[19]Veterinary Clinic Lexavet (blog, 3 October 2023): "Dog diarrhea – the most common causes and treatment" – The most common causes of acute diarrhea: eating unsuitable food, sudden dietary changes, viruses, bacteria, food allergies, stress; antibiotics or medications can also disrupt the gut. Diarrhea is common and often temporary, but severe diarrhea can be dangerous – monitor the dog's condition and contact a veterinarian if necessary. [19]

[1] [2] [11] [13] [15] [27]  The gut is your dog's immune powerhouse

https://tassufoods.fi/blogs/artikkelit/suolisto-on-koirasi-immunologinen-voimanpesa?srsltid=AfmBOopjbnZ2uhGHya4KyM7RntTalfuqnUWfP0CYO8Wglm0Lgaq1Ci4W

[3] [29] [30] [35] [36] [38] [43] [44] Effects of Postbiotic Administration on Canine Health: A Systematic Review and Meta-Analysis

https://www.mdpi.com/2076-2607/13/7/1572

[4] [6] [7] [8] [9] [10] [12] [14] [20] [21] [22] [23] [24] [25] [26] [40] [47] Understanding the diversity and roles of the canine gut microbiome | Journal of Animal Science and Biotechnology | Full Text

https://jasbsci.biomedcentral.com/articles/10.1186/s40104-025-01235-4

[5] [17] Gut microbiota composition is related to anxiety and aggression scores in companion dogs | Scientific Reports

https://www.nature.com/articles/s41598-025-06178-4?error=cookies_not_supported&code=82e32428-a40b-4947-b712-f4ac19ae767e

[16] [18] Impact of acute stress on the canine gut microbiota | Scientific Reports

https://www.nature.com/articles/s41598-024-66652-3?error=cookies_not_supported&code=dba1c2ff-9400-4076-8c31-b1781b9c74fb

[19] [42] Dog diarrhea – the most common causes and treatment - Veterinary Clinic Lexavet

https://lexavet.fi/koiran-ripuli-yleisimmat-syyt-ja-hoito/

[28] Comparison of the fecal microbiota of adult healthy dogs fed a plant ...

https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1367493/full

[31] [32] [33] [34] [37] [39] [41] Pre, Pro & Post-Biotics for Dogs: A Expert Guide

https://petjope.com/blogs/ingredients/pre-pro-post-biotics-for-dogs?srsltid=AfmBOop92yEtXBdsYZg2ixusQGnwj0AegwWQ2rnNTrqnNW603AtM35Rt

[45] A new combination of a prebiotic and postbiotic alleviates ... - Frontiers

https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2024.1392985/full

[46] Supplementation of a new combination of prebiotic and postbiotic ...

https://www.nature.com/articles/s41598-025-10280-y