Probiotics have become more and more popular in recent decades. While overall supplement sales have faltered, probiotic sales have soared. The sale of yogurt has increased even as sales of other dairy products have plummeted.
There’s a reason for all this hype. Recent studies have linked the gut biome to more than just proper digestion. Now, scientists know that a person’s probiotic load affects just about everything in the body, from the immune system to how the brain functions.
But even if probiotics have been proven to be beneficial for humans, does that really mean they are worth giving to your dog?
The answer is yes, but with a bold, necessary asterisk. To understand why this asterisk is necessary, we need to take a deep-dive into the world of the dog microbiome and the different probiotics available. Only then, can we get into the many positive effects the right probiotics can have on your dog’s health and longevity.
What Are Probiotics?
To understand what a probiotic is, we first need to understand the dog microbiome. Like humans, the doggy intestinal tract is filled with millions of bacteria and other microorganisms. These tiny cells live in the mouth, the stomach, and the small intestine, but the vast majority are found in the colon.
In addition to helping your dog digest fiber, these little creatures produce byproducts that help with the overall functioning of the gut and the absorption of nutrients. They also play a key role in defending the body against invasion by pathogens that your dog might pick up in their food or from licking the ground or chewing on an old bone.
Probiotics are the members of this microbiome that do all the good things listed above (and more!). This is an important distinction because some microorganisms are not as beneficial. These bacteria can produce toxins, infect the body if they escape the gut, or just overpopulate the colon and throw off the balance of the whole system.
In order to keep that balance in their own guts, many people turn to probiotic supplementation in the form of capsules that contain dried bacteria or fermented foods that contain live bacteria. Some of these same supplements can be helpful for your dog. But you’ll need to make sure you choose the right ones.
What Are Soil-Based Probiotics?
“Soil-based” probiotics simply describe beneficial microorganisms that live in the soil. These single-celled organisms help plants break down organic compounds and absorb nutrients while also helping to fight pathogens.
These tiny creatures often find their way into the gut of humans and animals through normal daily activities. Once in the body, many of these organisms provide the same benefits as they do for plants while living in the soil.
One key difference between soil-based probiotic strains and those used in fermentation, is they tend to be better able to handle the acid environment of the stomach. That’s because they have the ability to form tough shells around themselves when in undesirable environments. For this same reason, these types of probiotics do not need refrigeration.
Because they are more robust, these microorganisms are far more likely to survive long enough to make it to the gut alive, where they can provide the most benefit to the host.
What Makes Saccharomyces boulardii Different?
In general, when people talk about probiotics, they are talking about friendly bacteria. But not all beneficial microbes are ancient prokaryotes. In fact, one of the most beneficial probiotics for both humans and dogs is a single-celled yeast known as Saccharomyces boulardii.
This fact gives S. boulardii many unique abilities within the probiotic world.
In addition to the many health benefits, which we will get into in a moment, this little yeast is far more robust than most bacteria. Its large size and ability to withstand the stresses of the gastrointestinal tract mean it is much more likely to make it to the colon alive and functional.
Additionally, S. boulardii does not carry the same risk of over-infection that some bacterial probiotics do.
These yeast cells are incapable of colonizing the canine gut and cannot move beyond the gut wall to infect other areas of the body. As long as the probiotic supplement is taken daily, the host will receive the benefits without having to worry about any unwanted side effects or long term complications.
Most importantly, though, the fact that S. boulardii is a yeast and not a bacteria means it has the unique ability to survive antibiotic treatments, allowing more-normal digestion and fecal formation in dogs being treated for an infection.
Health Benefits of Probiotics
Preventing diarrhea in dogs on antibiotics isn’t the only thing S. boulardii is good for, though. Supplementing with this yeast and other soil-based probiotics can provide a huge range of benefits for your dog, some less expected than others.
Improved Digestive Health
One of the most obvious benefits of taking probiotics is improved digestion. But how these little creatures help our dogs achieve better nutrition and more normal stool is much more complex than you might think.
It starts with something called short-chain fatty acids, or SCFA.
When probiotics, including S. boulardii, feed, they produce SCFA as a byproduct. The host’s body uses these fatty acids to keep the gut lining healthy. SCFA creates smaller gaps between cells, preventing leaky-gut syndrome, and creates a thick mucus layer that lines the gut to protect those same cells from infection and damage.
Butyrate, a specific type of SCFA, helps the immune system build T-cells, a type of white blood cell important in reducing inflammation. A similar process helps reduce the reactivity of immune cells within the gut to prevent food allergies.
Additionally, SCFA can help reduce blood glucose levels and aid in more normal metabolic activity and help the body absorb important minerals like iron.
Even beyond creating SCFAs, probiotics help with the absorption of nutrients by producing enzymes that break down cellulose and other materials dogs are incapable of digesting.
Many dogs who suffer from gastrointestinal disturbances or disease, show signs of altered “brush border” enzymes like these. Supplementing with probiotics in dogs that suffer from digestive conditions can help reduce symptoms and improve malnutrition.
In fact, one study found that giving human patients with ulcerative colitis S. boulardii supplements resulted in 68% of patients reaching therapeutic success in symptom remission. In humans with Crohn’s disease, the use of S. boulardii resulted in significantly reduced bowel movements. Studies in dogs and other animals have shown similar results when treating inflammatory bowel conditions.
One such study followed a group of dogs intentionally infected with E. coli. Half of the dogs were given Bacillus coagulans (a soil-based bacteria) and half were given a placebo. The dogs who received the probiotic were over their diarrhea in just three days while the placebo group continued to suffer diarrhea for eight days. Additionally, the treated group shed less E. coli in their stool than the untreated group.
Healthy Immune System and Disease Resistance
The ability of probiotics to protect against infection starts with interactions between organisms in the gut and extends through the entire immune system in a way that scientists are only now beginning to understand.
A healthy gut biome is filled with beneficial bacteria and other microorganisms, which doesn’t leave much room for dangerous bacteria to colonize. This “crowd them out” method works surprisingly well to control the growth of infectious organisms. But the best probiotics do more to fight disease than just take up space.
S. boulardii, in particular, has been shown to act as a “decoy” for many infectious bacteria, including C. difficile and E. coli. The unique chitin, mannose, and glucan shell of yeast attracts these pathogens. Once infected, the incapacitated yeast cell simply passes in the stool, taking the infection with it.
In addition to acting as a decoy, some probiotics will produce specific substances when they encounter a pathogen. These secretions not only neutralize toxins produced by the pathogen itself but also stimulate an immune response in the host's body.
In fact, it has been shown that the immune system will produce different kinds of specialized immune cells in response to different types of secretions produced by the gut biome. These changes in immune function help the body prepare to fight specific pathogens even before an actual infection has been detected.
This same system of communication helps reduce unnecessary inflammation in the body by stimulating the immune system to create more regulatory T-cells during times of low risk. These cells prevent autoimmune attacks on organs and reduce the likelihood of allergies developing, especially in response to food.
The ability to dictate the functioning and growth of the immune system combined with the decoy effect is why scientists now believe that the gut microbiome contributes to 90% of a host’s functional immune system.
Healthy Body and Brain
The benefits of a healthy gut microbiome for your dog don’t stop at a stronger immune system and better digestive health. These symbiotic creatures affect just about every part of your pup’s body.
While working to digest food in the gut, bacteria create B vitamins that can be utilized by the host to promote cellular health and increase energy. They can also produce serotonin, a neurotransmitter that is important for proper mood regulation, appetite, sleep, and memory.
The gut biome also affects the brain in other ways.
Like the immune system, the central nervous system communicates directly with the gut and can be influenced by the secretions of probiotics. Dopamine and GABA levels change in response to these secretions and different probiotic blends have been found to have different effects on mood due to this process.
Additionally, a healthy probiotic load can help reduce how much cortisol the body releases.
The gut biome can even influence how our genes are expressed. This is one reason scientists are becoming more focused on probiotic health in infants. The same need for exposure to the right microorganisms early on likely exists in puppies as well.
When to To Give Your Dog Probiotics
Given the wide range of probiotic health benefits for dogs, the truth is, dogs of all ages and types will likely benefit from a quality probiotic containing soil-based bacteria and S. boulardii. But there are certainly times when using a probiotic is more important than others.
Here are some examples of when your dog will most benefit from a probiotic supplement:
- During antibiotic treatment. Studies have shown that when S. boulardii is given with antibiotics from day one, it can actually prevent antibiotic-induced diarrhea from occurring.
- During times of stress. Not only can stress cause diarrhea, but it can also weaken the immune system. Probiotics help with these two issues as well as with reducing cortisol output to keep your pup calmer.
- During diet changes. For sensitive pups, a simple diet change can lead to explosive diarrhea. Probiotics, especially S. boulardii, have been shown to prevent diarrhea even in extreme cases, such as when subjects are fed straight castor oil.
- Dogs suffering from chronic gastric conditions. Probiotics have been proven helpful when used alongside traditional treatments for IBS and other chronic enteropathies.
- When feeding a raw or part-raw diet. S. boulardii is especially effective in neutralizing E. coli and salmonella, two bacteria your pup is likely to encounter if they eat raw meat.
- During behavioral modification training. Because probiotics are so important for brain function and the ability to learn and remember, dogs going through behavior modification training for fear, aggression, or other issues may benefit from a probiotic supplement.
Whether you choose to give probiotics every day or only when the situation absolutely warrants it, it is important to keep in mind that most supplements won’t lead to colonization.
S. boulardii has been shown to take about 5 days to reach therapeutic levels in the gut and is completely gone within 4 days of stopping supplementation. Most bacteria present in supplements and fermented foods also fail to colonize the gut.
This means, if you want your dog to benefit from probiotics, you have to give them consistently.
Choosing a quality supplement containing soil-based probiotics, including S. boulardii, is also important since many products contain less stable microorganisms that will fail to reach the gut no matter how often you give them.
So next time you order yourself some probiotics, make sure you check what is in the product to assure it will actually help. And then, considered getting some special pup-formulated probiotics for fido, too.
Mounika, et al. “Effect of probiotic formulation containing Bacillus spp. on diarrhoea in dogs.” The Pharma Innovation Journal, 2019; 8(6): 81-85.
Simona D’Angelo, et al. “Effect of Saccharomyces boulardii in dogs with chronic enteropathies: double-blinded, placebo-controlled study.” Vet Record, March 2018; 182(9).
Blehaut, et al. “Disposition kinetics of Saccharomyces boulardii in man and rat.” Biopharmaceutics and Drug Disposition, Jul-Aug 1989;10(4): 353-64.
Mustafa Sinan Aktas, et al. “Efficacy of Saccharomyces boulardii as a Probiotic In Dogs with Lincomycin Induced Diarrhea.” Bull Vet Inst Pulawy, 2007; 51: 365-369.
Huiying Wang, et al. “Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review.” Journal of Neurogastroenterology and Motility, 2016; 22(4): 589-605.
Amir Qamar, et al. “Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice.” Infection and Immunity, April 2001;69(4): 2762-5.
Sara Seitz worked in the pet industry for over a decade. In addition to being a certified dog trainer, Sara gained experience working as the general manager of a dog daycare and boarding facility, as the creator and manager of a pet sitting company, as a groomer, and as a dog behavior evaluator. She also has a bachelors in animal behavior from CSU. Currently, Sara works as a freelance writer specializing in blog, article and content writing.