This is the second part of a two-part series on probiotics for dogs, written by my friend Danielle Marshall.  Her probiotic/digestive enzyme supplement can be found on her website at:

What are the best Probiotics for Dogs? 

There are so many probiotics for dogs on the market these days that say they’re for pets… How can a pet parent know which product is best?

On the surface, the human digestive process is much the same as that of our dogs.  But dig a little deeper, and we see there are some significant differences.

First, it’s important to understand that many probiotic formulas that claim to be made for dogs are just human products re-labeled and marketed for pets. Science has clearly identified specific strains of beneficial bacteria in dogs, some of which, are uniquely different from those in humans.  So, giving your dog a probiotic for humans likely won’t result in the desired benefit and could cause negative side effects. Secondly, quality of materials and the manufacturing process makes a big difference in the purity and viability of probiotic products. Many products on the market are manufactured with cheap unstable materials which may lose their beneficial properties before they are even purchased. Look for products manufactured in the USA in an FDA inspected facility that adheres to Good Manufacturing Practices (GMP certification).


What to look for in a Probiotic for your Dog

Probiotics for dogs are available in a variety of forms including dry powders, tablets (chewable and regular pressed tablets), liquids, treats and manufactured as part of a commercial food. While liquids often deliver the highest potency, they are much less stable, require refrigeration, and are more difficult to dispense to your dog. Dry powders are the most stable type of probiotic since the live bacteria are in a dormant state. As long as the product remains in the dry-inactive state, these probiotics can generally be stored for over a year from the manufacture date if kept cool and free from contaminants. Dry probiotic powders do not require refrigeration and will not react the same way to temperature change as liquid probiotics. Probiotic bacteria in dry powdered formulas is reactivated naturally in your dog’s stomach, then travels to the intestines where they begin to seed and multiply.

To be effective, however, the probiotic must remain alive as it travels from the mouth through the harsh stomach environment and into the intestine. Seeding of beneficial bacteria takes place in the small intestine, so the most stable forms of probiotics generally provide the biggest benefit.  Remember probiotics contain living organisms that are delicate and need to be cared for properly. Exposure to air, moisture and temperature extremes will affect their viability. That’s why, dry powder supplements are more desirable over probiotic chews, or dog food with probiotics. Simply put, the process of including probiotics in these types of products often kills the living organisms. If you desire a probiotic in tablet or chewable form, choose one that is cold-processed since heat processing would naturally destroy the viability of the supplement. Powders, cold-processed tablets and chews are shelf-stable, but should still be stored in a cool, dry location. Refrigeration is generally not required, but will enhance the overall shelf life of the product.


Your probiotic supplement should also include a Prebiotic, such as, inulin or FOS. Prebiotics serve as food to nourish the good bacteria in the gut and by creating a favorable environment in which the beneficial bacteria can flourish and grow. Prebiotics like inulin are plant fiber which can only be broken down in the colon. A fermentation process in the colon breaks down inulin (and other prebiotics) into short chain fatty acids, which nourish colon cells. These short chain fatty acids are produced when the friendly gut bacteria ferment the fiber in the colon which serves as the main source of energy for the cells lining the colon. Inulin also promotes a healthy pH in the lower gastrointestinal tract. Inulin supports absorption of calcium and magnesium in the gut. These are essential minerals for maintaining the structure and function of bones and for supporting cell metabolism.

Digestive Enzymes

Digestive Enzymes are another key component that will be included in the best probiotic supplements.  Digestive Enzymes assist in the breakdown and assimilation of fats, proteins, starch, cellulose from plants, dairy and proteins. The following digestive enzymes are examples of those to look for in probiotics for dogs.

• Lipase. Breaks down Fats and Triglycerides

• Protease and Bromelain.  Breaks down Proteins

• Amylase. Breaks down Starch

• Cellulase. Breaks down Cellulose from plants

• Lactase. Breaks down Dairy milk

While it is true that the pancreas produces enzymes to aid in food digestion, additional enzymes found in food also contribute to digestion and absorption. However, even relatively low temperature heat processing (120-160 degrees) and temperatures below freezing will break down enzymes.  Adding powdered enzyme supplements to room temperature food at the time of feeding is the best way to ensure adequate enzyme supplementation.

It’s important to note that dogs on natural raw diets receive the benefit of a number of enzymes not found in processed food. Dana Scott of Dogs Naturally magazine published an excellent in-depth article on the topic. Read Enzymes and Your Dog, Don’t Run Out.


Fundamentally, probiotics represent beneficial (good) bacteria which normally inhabit the bodies of humans and animals. Since 70-80% of the immune system is in the gastrointestinal tract, that’s where most of the beneficial bacteria live.  Scientific studies demonstrate solid evidence for nine species of probiotics with beneficial effects in dogs. Those strains include L acidophilus, L rhamnosus, B animalis, L fermentum, L reuteri, L salivarius, E faecium, L plantarum, and B coagulans.

Are more strains better?

Probiotics for dogs represent living organisms which will hopefully take up residence in the intestines, flourish and grow. Choose a formula with at least 4-6 strains, but no more than 8, and preferably strains from the list of those known to exist in the GI tract of healthy canines. Extra strains with no known effect in dogs can compete with and/or dilute the valuable strains rendering them less effective. Don’t be fooled by products making miraculous claims owing to large numbers of bacterial strains. Since research on the canine gut supports only about 9 strains (as of this writing), there’s no scientific reason to believe over-loading a product will have any beneficial effect and could in fact, lead to negative results.


Our pets rely totally on us, the pet parents, to provide them with everything they need. A quality probiotic supplement can go a long way towards supporting your dog’s gut health.  Regardless of the product you choose to purchase, be sure that it meets the following general guidelines:

Live viable bacteria. The product is not a probiotic unless the bacteria are live.

A formula created for dogs. An animal’s intestinal tracts contain species specific microflora, so a probiotic designed for humans isn’t necessarily beneficial for dogs and cats.

High potency. When it comes to probiotics the more potent the better. CFU stands for colony forming units and is a measure of how many living microbes are in the formula. Look for at least 1-5 billion CFU per serving for the most therapeutic effect. All quality probiotic supplements will list the CFU count on the label. If the product does not include this key measure, then it likely doesn’t contain a significant amount and may not contain any live microbes at all. Although less likely, you may also find a product with an inordinately large CFU count (40-60 billion). Scientific research doesn’t support products with counts this high. Instead, opt for a product in the range of 1-5 billion for a quality product.

Contains a prebiotic. Prebiotics like inulin or FOS which serve as nourishment for the beneficial bacteria and help to support maximum growth and development in the intestinal tract.

Stabilized form. Choose a Stabilized form (dry powder or cold-pressed tablet/chew) that doesn’t require refrigeration and will remain shelf-stable for up to a year.

Made in the USA. Probiotics are delicate molecules and are unlikely to survive the rigors of import from another country. Imported products are likely to come from China where process and quality controls are much less stringent than the USA. As an additional assurance, look for Good Manufacturing Practices (GMP) on the label of the product.

Purity. Probiotics for dogs are designed to increase gut health, so not all products are created equal. Be sure the probiotic doesn’t contain artificial colors, flavors, preservatives, sugar, salt, corn, wheat, soy or other undesirable ingredients.

Human grade vs feed grade. Quality of ingredients counts when it comes to probiotics. Feed grade ingredients are generally intended for livestock products and may contain undesirable components that may even be toxic to your dog.

Multiple bacterial strains. Different strains of bacteria exert different biological activities. Look for a product containing at least 4-6 different strains, but not more than 8. Some products may include as little as one strain while other products may list a dozen or more. Only 9 strains of bacteria have been studied extensively and are known to produce good results for dogs. Remember that probiotics represent live organisms, so each additional strain competes for absorption and colonization in the gut. “Extra” strains with no known effect in dogs can dilute the valuable strains rendering them less effective. We’re aware of one product being sold for dogs that includes 24 strains (only 2 of which are studied in dogs). Since research on the canine gut only supports about 9 strains (as of this writing), there’s no scientific reason to believe over-loading a product will have any beneficial effect and could in fact, lead to negative results.