Probiotics for Pets: Choosing the Right One

probiotics goldilock zone

Many manufacturers make the mistake of just taking human probiotic formulas and relabeling for pets. This usually manifests itself in products that are either:

1. Too Simple
Just a combination Lactobacillus acidophilus for dogs and Bifidobacterium formula.

2. Too Complex
A broad species/strain formula combining many different species (some as much as 14 per formula).

The Probiotic Goldilocks Zone

Somewhere between "too simple" and "too complex" is a probiotic formula that is just right for your pet.



These two words are often used interchangeably, and, in short, unless you're a microbiologist, you can disregard the word "strain".

That said, these two words do not mean the same exact thing, and if you'd like to geek-out on the details, here's our watered-down explanation:

"Species" is to "strain" as "dog" is to "breed".  
Just as there are numerous types of breeds of dog there can be numerous different strains within a single species of probiotic. (German Shepherds have different attributes than French Bulldogs, yet both are dogs),

Probiotics are often referenced by genus and species names, and less often the specific strain is referenced.  For example, the probiotic, Lacobacillus acidophilus, is the genus and species name for the widely used "acidophilus" probiotic. More rarely, the strain of acidophilus is called out, such as DDS, LA02, NFM and so on. 


Genus Species Strain
Canis lupus German Shepherd
Lactobacillus acidophils NFM

Why The Strain is NOT Important

Strains of bacteria are more often discovered or researched by the companies that market them. For this reason, the usefulness, claims, or beneficial attributes of any specific strain of bacteria over another may be considered controversial.

CFU (Colony Forming Units)


The answer is: Not too many! But, it also depends on the specific health of your pet.

The CFU is the estimated viable (living) amount of bacteria in a sample. Given the fact that once these guys reach their destination in the colon of your dog or cat, a quality probiotic will multiply hundred-fold

When it comes to probiotics for dogs and cats, we see a random approach to formulation ranging from extremely low CFU (i.e. 200-500 million), to extremely high CFU (i.e. 58 billion). This is also reflected in the types of strains used in each formula.

The amount of CFU needed depends on the problem that is being treated and the research available for dogs and cats is not as robust as it is in humans. For a pet with IBS, a higher CFU count is needed. Pets with diarrhea, a lower CFU of probiotics is in order (and higher counts may be contraindicated for diarrhea). Our findings show that for general health maintenance, 1-4 billion CFU is very effective for pets depending on the animal's weight.

There are 360 billion CFU of animal-researched probiotics in a large canister of Probiotic Miracle®, each scoop provides 1 billion CFU. This makes modifying dosages, higher or lower, for your dog or cat very simple.



Again, the answer is: Not too many!

There is good reason for not supplying too many different species of probiotics at once.

Choosing the best probiotic for your pet is not as simple as choosing the one with the most species or CFU count. To choose the right probiotic that will be the MOST EFFECTIVE for his needs, find one that has the research backing it. 

If you do choose a probiotic formula with multiple strains, it is important for every one of those strains to not compete with one another, as well as be well-studied for their effectiveness in dogs and cats.

In our opinion, a 10-14 species/strain probiotic for pets is a haphazard formulation at best. There is little evidence that these extra species will help your pet's issue, but there is good reason to believe that the unneeded ones will dilute the value and effectiveness of the beneficial strains.

Through our body of research, from literally hundreds of probiotic strains to choose from, we find that there are 6 species of probiotics that cooperate effectively together to benefit your pet. Probiotic Miracle® contains guaranteed potency of these 6 highly-studied strains of bacteria.


  1. Competition
    Some strains are not complimentary and may compete with one another for absorption.
  2. Lack of Research
    Most of the probiotic strains have never been researched for dogs. Use of these strains and their benefit are merely speculative and likely based on a human-system model. 
  3. Low Quality or Poor Potency
    These formulas tend to include extremely low amounts of each probiotic strain. Your dog does not get the therapeutic amount or even the preventative benefits it needs.


The species, L. acidophilus, it is not enough, but it is a great species of bacteria for the gut. A truly high quality strain of acidophilus, in the right CFU amount, can potentially offer more benefit for your dog or cat than a formula with many low value strains. That said, for the most benefit to your pet, a targeted probiotic should contain more than just acidophilus.

Our research indicates that there are about 6 well-tested species of probiotics that offer valid benefits to dogs and cats.


When it comes to probiotics for dogs and cats, we've seen a haphazard approach to formulation... from extremely low CFU to extremely high. From formulas with only one or two species, to products that include almost every species imaginable. We said...

There are 6 strains of probiotics that are known to cooperate effectively together to benefit your pet.

Probiotic Miracle® contains guaranteed potency and fully researched bacterial species plus years of proven results for dogs and cats.


B. animalis

Probably the most studied probiotic strain in dogs is B. animalis. It has been demonstrated to reduce acute diarrhea, and improve overall intestinal health. However, most dog probiotic products do not contain this strain. We believe that over time all of the formulas will move to containing B. animalis because of the vast research.

Vet Ther. 2009 Fall;10(3):121-30: Clinical benefits of probiotic canine-derived Bifidobacterium animalis strain AHC7 in dogs with acute idiopathic diarrhea.

Commentary: In this study B. animalis on its own reduced the resolution time in half from 6 days to 3 in dogs. Vet Microbiol. 2009 Oct 20;139(1-2):106-12. Epub 2009 May 19.

Portrait of a canine probiotic Bifidobacterium animalis, from gut to gut.


Bifidobacterium animalis adhered to epithelial cells, transited the murine gastrointestinal tract to high numbers and significantly reduced S. typhimurium translocation. B. animalis  consumption significantly reduced the carriage of Clostridia, in particular Clostridium difficile, in dogs. This study describes the isolation and screening of canine-derived bacterial strains with commensal traits. The results demonstrate that B. animalis has significant potential for improving canine gastrointestinal health.”

Commentary: Clostridium difficile is the pathogen that primarily causes diarrhea. The fact that B.animalis has such a dramatic effect on C. difficile, makes it really the number one choice for dealing with acute diarrhea.

L. acidophilus

Lactobacillus acidophilus as been show to be especially good with use in puppies. L. acidophilus was shown to increase weigh gain/growth in canines (Note it is thought that probiotics are critical in the puppy stage also for bolstering foundational immunity). Puppies supplemented with L. acidophilus were found to display less symptoms of allergies and other diseases in older years.

Arch Tierernahr. 2001;55(3):243-53.

L. rhamnosus

Along with L. fermentum, and L. salivariousL. rhamnosus is one of the highest concentrated bacteria found in normal healthy canine microbiota. Formulas that do not have this probiotic in fairly high amounts should not claim to be specifically formulated for dogs.

J Appl Microbiol. 2006 Jul;101(1):131-8. Lactic acid bacteria isolated from canine faeces.

“SIGNIFICANCE AND IMPACT OF THE STUDY: The selected LAB strains are among the first host-specific LAB with antimicrobial activity isolated from canines that could serve as potential probiotics for canine use.”

Commentary: This study shows that L. rhamnosus is one of the foundational bacteria found in canine intestinal tracts.

L. fermentum

Again one of the naturally concentrated bacteria inherit to canine microbiota, L. fermentum has strong survival characteristics and the ability to significantly modify the intestinal microbiota.

J Appl Microbiol. 2006 Jul;101(1):131-8. Lactic acid bacteria isolated from canine faeces.

Appl Environ Microbiol. 2006 Oct;72(10):6539-43. 

L. reuteri

As part of the Lactobacillus family, L. reuteri has many of the broad ranging health benefits. In dogs though they have found that reuteri may be the most resistant and may be especially helpful in controlling canine intestinal infections.

Food Sci. 2007 Apr;72(3):M94-7. Isolation and characterization of Lactobacillus species having isolation and characterization of Lactobacillus species having potential for use as probiotic cultures for dogs.

L. salivarius

Again, one of the naturally concentrated bacteria inherent to canine microbiota. Strong and viable, this probiotic should always be in a natural canine probiotic formula.

J Appl Microbiol. 2006 Jul;101(1):131-8 Lactic acid bacteria isolated from canine faeces.