Probiotics Boost Canine Overall Health

These health-boosters are not expensive and easy to find and feed.


[Updated August 22, 2018]


1. Give probiotics to any dog under chronic or acute stress, or who receives antibiotics.

2. For dogs with allergies or digestive problems, use a variety of probiotics with several strains of benefical bacteria.

3. When buying food sources of probiotics, look for the freshest products possible. The live cultures in products such as yogurt and kefir lose potency as they sit on shelves.

Who hasn’t heard of “friendly” or “beneficial” bacteria? Even acidophilus, once a confusing tongue-twister, has become as familiar as yogurt, in which it’s the active ingredient.

One reason beneficial bacteria have worked their way into the public’s consciousness is the excellent press they have received for helping repair damage done by antibiotics. Broad-spectrum antibiotics target not one but all strains of bacteria, leaving us thoroughly disinfected.

But no antibiotic kills 100 percent of the body’s bacteria. A few always survive, some harmful and some essential to good health. Often the harmful organisms thrive and reproduce, overwhelming the beneficial strains that normally keep them in check, resulting in a host of new health problems. According to the Royal Society of Medicine of Great Britain, fully 90 percent of chronic diseases are caused by an unhealthy intestinal system.

probiotics for dogs

This helps explain why antibiotic drugs have long-term as well as short-term side effects. Their long-term side effects include impaired digestion, gastrointestinal discomfort, diarrhea, chronic or systemic yeast or fungal infections, lowered immunity, and the creation of drug-resistant or “super germ” bacteria that worry public health officials around the world.

Bacterial Homeostasis: the Body’s Balancing Act

Homeostasis is a Greek word meaning stable and balanced. When the body’s systems are in homeostasis, they maintain a stable body temperature, a constant blood pH, balanced blood sugar, normal blood pressure, and a healthy population of microorganisms. For the last to occur, the body needs more beneficial than harmful bacteria. In fact, most experts estimate that for optimum health, the body should contain 80 percent beneficial bacteria and no more than 20 percent harmful bacteria.

Even those who haven’t taken antibiotics may lack beneficial bacteria because of poor diet, stress, illness, prescription drugs, travel, or environmental factors. Anything that interferes with the growth and reproduction of beneficial bacteria interferes with good heath.

Just as our dogs share many human health problems, they are adversely affected by the antibiotics they routinely receive from veterinarians as well as by environmental toxins and diet. Many pet foods contain ingredients that nourish harmful bacteria, such as sugars and starches, along with ingredients that damage good bacteria, such as chemical preservatives.

In both species, healthy intestinal bacteria typically consist of dozens or hundreds of different species. These bacteria produce enzymes; improve digestion; lower the risk of colitis, irritable bowel syndrome, and similar disorders; prevent diarrhea; synthesize vitamins; detoxify the body; and protect against toxins. In dogs, conditions that coincide with bacterial imbalances include digestive disorders, flatulence, constipation, diarrhea, urinary tract infections, allergies, diabetes, arthritis, vitamin B deficiencies, chronic ear infections, skin and coat problems, susceptibility to bacterial or viral infections, bad breath, poor immune response, and, in some cases, confusion or behavioral problems.

Keeping Bad Bacteria in Check

Healthy intestinal bacteria inhibit the growth of pathogens such as viruses, fungi, parasites, and harmful bacteria.

Escherichia coli, or E. coli, is usually a harmless inhabitant of human and animal intestines, but the strain E. coli O157:H7 produces a powerful toxin that can cause severe illness. It was first identified during a 1982 outbreak of bloody diarrhea that was traced to contaminated hamburger.

Investigative journalist Jo Robinson has documented many benefits of feeding cattle on grass instead of in commercial feedlots. Among other things, a natural grass diet provides ideal conditions for the growth of beneficial bacteria in the gut of the cattle. Recent research at Cornell University shows that grass-fed cattle have less than 1 percent of the E. coli bacteria found in feedlot cattle, while other studies show that grass-fed chickens carry significantly lower amounts of E. coli than chickens raised indoors on factory farms.

Robinson explains that because a grain diet increases the acidity of bovine digestive tracts, the E. coli that grows in feedlot cattle is less affected by hydrochloric acid in the human stomach, which would otherwise destroy it. Beneficial bacteria in the digestive tracts of dogs and people help prevent acid-resistant E. coli from proliferating when they eat beef from feedlot cattle.

The Salmonella family includes more than 2,300 types of one-celled organisms, two of which, Salmonella enteritidis and Salmonella typhimurium, are the most common. Salmonella can contaminate meat, poultry, dairy products, eggs, seafood, and some fruits and vegetables, but it is especially associated with chickens and eggs from factory farms. Beneficial bacteria help keep Salmonella bacteria in check.

Clostridium difficile is a rod-shaped bacteria that produces two toxins that interact to cause a serious, potentially fatal disease that produces diarrhea, abdominal cramping, inflammation of the colon, and meningitis-like symptoms. In June 2006, the Centers for Disease Control alarmed therapy dog organizations by publishing a report from researchers at the University of Guelph in Ontario, Canada, in which a therapy dog was shown to carry a human epidemic strain of C. difficile.

The study’s lead author, Sandra L. Lefebvre, explained, “One particular strain of C. difficile has been implicated in outbreaks of Clostridium difficile-associated disease (CDAD) in hospitals in North America and Europe and appears to be spreading internationally at an alarming rate. We report this toxin-variant strain of C. difficile in a healthy four-year-old Toy Poodle that visits persons in hospitals and long-term care facilities in Ontario weekly. C. difficile was isolated from a fecal sample collected in the summer of 2004 as part of a cross-sectional study evaluating pathogen carriage by visitation dogs . . . CDAD cases were occurring at increased frequency in the facility around the time the dog’s fecal specimen was collected.”

While this is the first documented case of the human epidemic strain of C. difficile in a dog, the study does not prove that interspecies transmission of C. difficile oc-curs. “However,” it states, “that possibility exists, as is becoming apparent with other pathogens, such as methicillin-resistant Staphylococcus aureus. The recurrent exposure of this dog to human healthcare settings suggests that the animal acquired this strain during visits to the hospital or long-term care facility, either from the healthcare environment or contaminated hands of human contacts. We recommend that future studies evaluating the dis-semination of this strain and investigations of the movement of C. difficile into the community consider the role of animals.”

According to Pennsylvania State University College of Medicine professor Kelly Dowhower Karpa, PhD, in her book Bacteria for Breakfast: Probiotics for Good Health, numerous studies show that the beneficial bacteria Saccharomyces boulardii has cleared C. difficile in an encouraging number of cases.

In other studies, Dr. Karpa writes, one strain of Lactobacillus given at high doses (10 billion live bacteria daily) for as little as 7 to 10 days following conventional antibiotic therapy has cured patients experiencing relapsing C. difficile diarrhea.

Because beneficial bacteria are the body’s first line of defense against pathogens, maintaining a large and vigorous population of these friendly microbes can help prevent all types of infection as well as their transmission from people to animals and vice versa.

Good Bacteria to the Rescue

Thanks to the growing popularity of beneficial bacteria, it isn’t difficult to increase their population for improved health and immunity.

Several strains are grown in laboratories for use in supplements, including the familiar Lactobacillus acidophilus. Other popular bacteria include L. bulgaricus, L. rhamnosus, L. casei, L. plantarum, Streptococcus faecium, S. thermophilus, and Bifidobacterium bifidum, formerly known as L. bifidus. L. acidophilus, which resides mostly in the small intestine, is the strain most associated with animals, while B. bifidum, which resides mostly in the large intestine and colon, is most associated with humans.

Many yogurt producers have recently changed their formulas in response to consumer demand for probiotics. Stonyfield Farm, a leading maker of yogurt and organic dairy products on the East Coast, now adds six live cultures to every product: L. bulgaricus, S. thermophilus, L. acidophilus, bifidus, L. casei, and L. reuteri. As the company’s website explains, “Probiotics protect us from pathogens such as Salmonella and others by preventing their attachment to the intestinal lining. They interfere by blanketing all available surfaces, thus limiting the growth of microscopic invaders like Giardia, Candida yeast, and bacteria such as E. coli.

“Studies have shown that probiotic cultures benefit health in several ways – by suppressing pathogenic bacteria, helping control antibiotic-associated diarrhea, helping prevent traveler’s diarrhea and leaky gut syndrome, improving lactose tolerance, producing some vitamins and enzymes, decreasing toxins and mutagenic reactions, improving carbohydrate and protein usage, strengthening innate immunity, creating a barrier effect in the intestinal tract, and reducing infant food allergies and eczema.”

Beneficial bacteria have an ancient history, for people have been using them to culture and preserve foods for millennia. They are ingredients in traditionally fermented foods like sourdough bread, yogurt, kefir, sauerkraut, tempeh, miso, and amazake.

Probiotics for Your Dog

The word probiotic literally means “for life,” as opposed to antibiotic, which means “against life.” Probiotics are strains of beneficial bacteria sold as supplements for human or pet use. All health food stores and many pet supply stores carry several brands of L. acidophilus and other strains that can help improve your dog’s digestion and immune function.

Probiotic supplements are especially beneficial for newborn puppies, to increase the number of desirable organisms in their digestive tract. They are also well-suited to help dogs of all ages cope with stress – travel, intensive training, competition, and boarding. It’s smart to use them to boost the immune system following surgery, parvovirus infections (which affect the small intestine), chronic diarrhea, and whelping. They should also be a standard prescription during and after the use of any antibiotic.

probiotics for dogs

Buying a probiotic supplement and following label directions is the simplest way to introduce a new supply of live beneficial bacteria to your dog’s digestive tract. Some brands require refrigeration; others have a long shelf life at room temperature. The supplement may be sold as a powder, liquid, or in tablets or capsules, some of which are enteric-coated to survive stomach acid and break apart in the small intestine. Depending on the brand, label instructions may recommend feeding the product on an empty stomach between meals, with food, or immediately before or after eating.

Some products contain a single strain of beneficial bacteria, such as L. acidophilus, while others contain multiple strains. Experts disagree as to which approach is better. Single-strain products tend to be backed by more clinical research, but some advocates favor multiple strains because that’s what the body contains.

The newest probiotics on the market are not bacteria; they are homeostatic soil organisms, or HSOs, which literally come from dirt. Soil contains so many different microorganisms that science has defined less than 1 percent of the estimated total. One gram of soil (about a teaspoon) can contain as many as 10,000 microbe species.

Until recently, dogs, cats, and people all over the world ingested a constant supply of HSOs. That no longer happens in the U.S., where indoor lifestyles and cleanliness keep HSOs out of our mouths and food supply. Now medical researchers are linking asthma, allergies, and other common health problems to a lack of exposure to everyday dirt, germs, and HSOs, especially during early childhood. Some vets make the same connection to puppies and kittens.

The manufacturers of HSO supplements grow organisms discovered in pristine parts of the world where the number of beneficial microbes in soil is unusually high. These microbes are chosen for their ability to destroy molds, yeasts, fungi, viruses, and harmful bacteria, and are usually combined with several strains of beneficial bacteria.

Time to Heal

How long does it take to repair the body with probiotics if your dog has taken antibiotics? Estimates from researchers and veterinarians range from several weeks or months to a year or several years.

The fastest recoveries are experienced by dogs who have a good supply of surviving native bacteria – that is, beneficial bacteria that they obtained from their mothers’ milk or from supplements within hours of birth – which are supported by a diet that feeds them instead of one that feeds their harmful competitors.

Another way to recover quickly is to be a good host for the beneficial bacteria introduced in supplements, so that the dog’s system provides what these bacteria need in order to reproduce and colonize.

Not all beneficial bacteria colonize or continue to multiply after the patient stops receiving probiotic supplements, but some will if given the right growing conditions, and even beneficial bacteria that don’t colonize can improve the digestive tract for as long as they are taken.

Feeding Beneficial Bacteria

Probiotics are beneficial bacteria. Prebiotics are the foods that feed them. In addition to supporting beneficial bacteria that are added to the system by probiotic supplements, prebiotics nourish whatever native bacteria survive antibiotic treatment.

In his book Cultivate Health from Within, Khem Shahani, PhD, one of the world’s leading research authorities on the role of Lactobacilli and gastrointestinal bacteria, explains the conditions for a food to be an effective prebiotic:

• It must pass through the upper gastrointestinal tract without being absorbed or hydrolyzed;

• It must be selectively fermented by a limited number of potentially beneficial bacteria in the colon;

• It must improve the composition of intestinal bacteria in favor of beneficial strains; and

• It should improve the host’s health.

Dr. Shahani lists several foods and food ingredients that satisfy these criteria and which belong to a special class of carbohydrates called oligosaccharides. Garlic, bananas, chicory, and milk are examples. Several oligosaccharides, including FOS (fructooligosaccharides) and GOS (galacto-oligosaccharides) are sometimes used as ingredients in yogurt, cultured dairy products, and other foods as well as in probiotic supplements. FOS and GOS ingredients are most popular in Europe and Japan, where they are used in more than 500 foods and nutritional supplements.

Another popular FOS prebiotic is the Jerusalem artichoke or sunchoke (it’s a member of the sunflower family), which contains inulin, a favorite food of lactobacteria. Jerusalem artichoke flour, for use in cooking, is widely sold in Japan.

Sweet whey, the part of milk that is separated out in the cheese-making process, is high in lactose, making it an ideal food for intestinal bacteria.

“In theory, prebiotics consumed alone might be able to deliver benefits, provided that the beneficial bacteria are indeed present in the GI tract in sufficient numbers,” says Dr. Shahani. “Today many probiotic supplements available in the marketplace now contain prebiotics. Such products (where probiotics and prebiotics are com-bined) are called synbiotics. This approach may provide an efficient mechanism for introducing and then enriching health-promoting probiotic bacterial.”

Prebiotics such as sweet whey and FOS should be introduced gradually, however, because they ferment in the large intestine, producing gassiness, abdominal discomfort, belching, bloating, and flatulence until the body adjusts.

Foods such as sauerkraut and other lactofermented vegetables contain and feed beneficial microbes, making them both probiotics and prebiotics. Lacto-fermentation breaks down and releases gases before these foods are consumed, making them far less likely to cause adverse reactions. In fact, dogs receive far more nutrition from lactofermented vegetables than from the same untreated vegetables, even if they are pureed or juiced. This is because lactofermentation breaks down, tenderizes, and predigests vegetables, increasing their vitamin content. Many natural food markets sell raw, unpasteurized sauerkraut, kimchi (Korea’s traditional sauerkraut), and other lactofermented fare. But these foods are easy to make at home, with or without special equipment. (For details, see “It’s All in How You Make It,” March 2001.)

Another easy addition to your dog’s diet is homemade yogurt. Goat milk is often recommended for dogs because it’s easier to digest than cow’s milk, and when its lactose is broken down through fermentation, it’s far less likely to cause digestive problems than other dairy products.

Commercially produced yogurt, including “live culture” brands, lose potency as they sit in stores, even on refrigerated shelves. Making your own in an electric yogurt maker is the easiest way to insure that your dog receives the maximum number of live cultures possible. If you let yogurt ferment undisturbed for 24 hours, beneficial bacteria will break down 100 percent of its lactose for maximum digestibility.

Kefir, another fermented dairy product, is even easier to make because it doesn’t require heat. Kefir’s vigorous beneficial bacteria, which easily colonize in the digestive tract, include Lactococus spp., Leuconostoc mesenteroides, Lactobacillus kefyr, Kliyveromyces marxianus, and Saccharomyces unisporus.

Don’t underestimate the health benefits of lactofermented foods. In 2005, researchers at Seoul National University in Korea announced that a culture fluid of Leuconostoc kimchii, a beneficial bacteria in kimchi, showed clear remedial effects for chickens suffering from bird flu, Newcastle disease, and bronchitis. Previous research showed that Pediococcus pentosaceus, another lactic ferment from kimchi, successfully prevented infection from harmful bacilli, including Helicobacter, which causes gastritis, and Listeria and Shigella sonnel, which cause food poisoning. Some research suggests that traditional European sauerkraut may help protect dogs and people from cancer.

Beneficial bacteria may be tiny microbes, but they’re big supporters of your dog’s immune system. Yours, too!

A long-time contributor to WDJ and author of The Encyclopedia of Natural Pet Care, Natural Remedies for Dogs & Cats, and other books, CJ Puotinen lives in New York with her husband, a Lab, and a tabby cat.


  1. Great post, thank you. I’ve been sourcing raw goat milk for 7yrs, which my dogs love as a treat, but I also make kefir and kefir cream cheese, which is a simple process of separating the whey from the kefir. One of my dogs prefers the cheese and I can also tolerate it and its great for things like decorating their birthday plate, the consistency works well in a piping bag.