Probiotics for dogs, probiotics for horses

Probiotics for Dogs and Horses: Live Performers for GI Health

Before jumping into the well-established benefits of probiotics for dogs and probiotics for horses, we need a little backstory. Let’s take stock of what we know at this point about the digestive health needs of humans, as well as our canine and equine friends.


There is a tremendous amount of research going on in the US, the EU, and Asia focused on the importance of the microbiota to body system health. As this research has illuminated, mammals including horses, dogs, and humans actually contain more microbe genome than their own. In humans alone, up to 100 trillion bacteria representing 500-1000 different species co-exist in the GI tract. “Probiotics” are a variety of especially beneficial microbes that make up just a part of this vast microbiota.

Environment, food, and DNA play an important part in the unique microbiota of our bodies. Each horse, each dog and each human has a unique colony of microbiota at work. There is overlap, by the way; people who live with dogs, for instance, will share some of the same micro-organisms as their canines.

Other environmental factors abound. Babies that are born through the birth canal share many of the same micro-organisms as their mother. When a child is born by Caesarean section, they do not get the micro-organisms that reside in the birth canal. Farm workers have a different percentage of micro-bacteria colonies than city workers. If you garden without gloves, you expose your skin to a host of beneficial micro-organisms from the soil. When horses and dogs roll in the grass or dirt, they’re helping colonize their largest organ (the skin).

The Good and the Bad:

In any healthy body system, there are colonies of beneficial micro-organisms, and colonies of harmful micro-organisms. The beneficial micro-organisms help to keep the harmful micro-organisms in check. When this balance is disrupted, the harmful micro-organisms can take over. Having a healthy body system does not mean eliminating all the harmful bacteria; it simply means that colonies of beneficial bacteria are larger and stronger than colonies of the harmful ones.

The GI Tract:

The intestinal microbiota play crucial roles in metabolic, nutritional, physiological, and immunological processes. The metabolic activities lead to the production of short-chain fatty acids, certain vitamins (K, B12, folic acid) and amino acids. The intestinal microbiota also participate in the defense against pathogens, the development/maturation/maintenance of the GI sensory and motoric functions, as well as maintenance of a healthy intestinal barrier and mucosal immune system.

The type and number of microbial species that colonize the GI tract depend on several factors: the inflammatory state of the host, the presence of antibiotics or other medications, stress levels, diet, genetics, age, and a host of additional environmental factors.

Viable Probiotics:

Viable or “live” probiotics are measured in Colony Forming Units (CFUs). Viable probiotics are capable of adhesion to host mucosa in the GI tract; in fact, their ability to do this is a key determinant of probiotic efficacy. The higher the CFUs, the greater the number of viable, beneficial bacteria capable of adhesion and increasing colonization.

Since the microbiotic cell population is estimated in the trillions, the probiotic number needed by horses is, at minimum, about 100 billion CFUs. For sick horses, the number of required CFUs can easily rise to 400 billion or more. The requirement for dogs is proportionally smaller, ranging from one to five  billion CFUs.

Whether you’re comparing probiotics for dogs or probiotics for horses, remember: if you do not see a CFU number stated on the product label, it is not a viable probiotic.

You can find all of this important probiotic strain and CFU information clearly listed on these BioStar products:


Prebiotics are simply food for the microbiota of the GI tract. They include fructo-oligosaccharides (FOS) like inulin (not “insulin”) and other oligosaccharides. Common prebiotic foods for horses include hay, grass, chicory root, dandelion greens, and bananas. Prebiotic sources for canines include beans, lentils, peas, fruits, and vegetables.

Yeast Probiotics and Lactobacillus Probiotics:

Yeast probiotics (Saccharomyces species and Enterococcus species) help ferment and break down fiber in the hindgut. Lactobacillus (lactic acid bacteria) are found throughout the GI tract, in the respiratory tract, and in the oral cavities.

In Ayurvedic medicine, yeasts can be either warming or heating to the GI tract, while milk (a source of Lactobacillus strains) is cooling. Horses or dogs with diarrhea will benefit from a cooling probiotic rather than a heating one. Horses that need to gain weight, and are not ulcer-prone, benefit from yeast probiotics. Older horses who have lost some of their “digestive fire” with age, also benefit from yeast probiotics. Ulcer horses or ulcer-sensitive horses benefit from the Lactobacillus probiotics (often indicated simply as “L.” probiotics).

When to use Viable Probiotics:

Viable probiotics for horses are recommended during periods of stress: shipping, hard training, competition, after worming, during and after antibiotic therapy, for idiopathic diarrhea (diarrhea of unknown origin), or during a change in diet.

Horses that live out, have access to pasture and forage 24/7 do not need probiotics in most cases. But horses that are confined, with a limited amount of turnout, will benefit from a daily viable probiotic.

Canines that live on farms where they get to roll in dirt/grass may not need probiotics for dogs like suburban or city dogs will. However, exposure to chemical fertilizers, home cleaning products, pesticides, and herbicides do increase the need for daily viable probiotics.

How to use Probiotics with Antibiotics:

On the human side of antibiotic therapy, there are warnings against taking tetracycline with calcium/milk products. According to the FDA, this is not true for doxycycline, which is not markedly influenced by the simultaneous ingestion of food or milk. Accordingly, the Merck Veterinary Manual cautions that tetracycline absorption is decreased by milk and milk products, antacids, and iron preparations. However, these negative interactions are not as evident with the use of doxycycline and minocycline.

In general, when using viable probiotics alongside antibiotics, it is a good idea to separate the two and not feed both simultaneously. Wait 2-4 hours after antibiotic administration before feeding a probiotic.

In the post-antibiotic therapy phase, it is wise to continue with viable probiotics for as many days or weeks as the horse or dog was given antibiotics. This is to help support new, beneficial colonization of the GI tract.

GMO’s in Probiotics:

If you are concerned about GMOs (Genetically Modified Organisms), you will need to verify that the probiotics in your feed and supplements are GMO-free. Sugar is often used in the fermentation process of Lactobacillus, and the most common source for this in the US is beet pulp, which is predominately GMO. The yeast Saccharomyces includes over 1,000 subset strains, some of which are genetically modified. This includes not only probiotic yeast, but brewer’s yeast and nutritional yeast.

The Take-Home Message for Probiotic Supplements:

Each horse and dog has a unique microbiota that is best supported with a multi-strain probiotic. Remember to always check those CFUs on the label to make sure that you’re using a viable probiotic. As detailed above, probiotics for horses need to show a CFU number in the hundred billions, not millions, for colonization, while probiotics for dogs need a CFU count in the low billions for the same efficacy.

Proper support of the microbiota will pay off, helping take better GI care of your horses, dogs, and you.
Probiotics for dogs, probiotics for horses

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