Lactobacillus rhamnosus: An Underrated Probiotic Player

Lactobacillus rhamnosus: An Underrated Probiotic Player

Lactobacillus is a lactic acid bacteria that is a common component of equine and canine probiotic formulas.  This genus belongs to the Firmicutes, a phylum that constitutes a significant proportion of the microbiota in the GI tract: “The complex intestinal microbiota of healthy horses is dominated by the bacteria phylum Firmicutes with 46-79% of identified 16S rRNA sequences in equine feces.”  (Costa, et al., 2012)

But Lactobacillus is much more than just the strains we read on labels: L. acidophilus, L. casei, L. reuteri, L.plantarum, L.delbrueckii, etc.  There are over 180 species of Lactobacillus, which shows how diverse bacteria are in mammalian bodies.

One Lactobacillus strain that is less well known in equine and canine supplementation is Lactobacillus rhamnosus.  This strain has demonstrated ability to modulate the respiratory immune response.  L. rhamnosus was discovered in 1983 in the intestines of a healthy human.  It was considered remarkable for its ability to survive and thrive in highly acid environments such as the stomach.

The microbiota
The GI tract of horses is inhabited by diverse colonies of bacteria, protozoa, and fungi.  Each horse has a unique range of microoganisms affecting the digestive system, immune stimulation, pathogen protection and metabolism.  However, the GI tract is not the only site of microorganisms in the body: the equine microbiome is an aggregate of microorganisms that reside in tissues, fluids, the skin, lungs, saliva, oral mucosa, reproductive glands, as well as the GI tract.  There are so many diverse bacteria and other microbes in mammalian bodies that they equal the number of body cells.

The respiratory tract
The respiratory tract, including the mouth, harbors diverse colonies of interacting microbiota.  Studies have shown that certain probiotic lactic acid bacteria strains can exert their beneficial effect on the host through their immunomodulation activity.  These strains have been termed immunobiotics.
[Villena J, Salva S, Barbieri N, Alvarez S.  “Immunobiotics for the prevention of bacterial and viral respiratory infections.” CRC Press (2013). P, 128-68]

While most research has focused on the immunostimulatory activities of lactic acid bacteria in the gastrointestinal tract, several recent studies have clearly demonstrated that strains of Lactobacillus are immunobiotics capable of improved protection against respiratory pathogens.

L. rhamnosus
Research has shown that L. rhamnosus is able to improve specific cytokines in blood, which can induce a mobilization of white blood cells known as T helper cells or T lymphocytes.  One particular study suggested that L. rhamnosus is “a potent inducer of antiviral cytokines, and may be useful as a therapeutic or prophylactic agent to control respiratory virus infection.”
[Villena J, Chiba, E, et al.  “Orally administered Lactobacillus rhamnosus modulates the respiratory immune response triggered by the viral pathogen-associated molecular pattern poly (I:C)”, BMC immunol. 2012; 13: 53]

Like yeast probiotics, L. rhamnosus is not able to colonize the GI tract of adult equines; this means these microorganisms must be supplemented daily.  L. rhamnosus is capable, however, of colonizing the GI tract of foals.

When to use L. rhamnosus:

  • If your horse suffers from chronic respiratory disease such as asthma or COPD, adding rhamnosus as well as omega-3 supplementation can be beneficial.
  • For horses dealing with upper respiratory infections caused by bacteria or viruses, supplementing with rhamnosus, particularly in the onset of the infection, can help support the immune response.
  • If your horse is in a barn or herd that has been exposed to an upper respiratory virus, start supplementing with rhamnosus immediately as studies have shown that it can work prophylactically. Likewise, if your horse is shipping a long distance  it is advisable to give probiotics including L. rhamnosus for maintaining a healthy gut, immune system, and for respiratory support.
  • If your horse has been diagnosed with Lyme disease, support for the immune system is important, and active probiotic strains including rhamnosus are recommended.


When supplementing with probiotics…
Make sure you are feeding a probiotic that contains more than one strain of active bacteria.  The microbiome is diverse, and a probiotic should reflect the diversity of the microbiome by containing different strains of active microorganisms.  If a label states “dried yeast fermentation product,” then it is not “alive” and is not considered an active microbial.

Check the colony forming units (CFUs) on the label: the higher the CFUs the better.  Research from the University of Toronto at Guelph suggests 100 billion CFUs as a minimum for colonization, and horses with immune or GI tract issues may need as much as 400 billion CFUs per day.

Microencapsulation is an important feature in a probiotic formula because it protects the strains from deterioration in the stomach.  The pH of the stomach lessens the survival rate of many microorganism strains. Microencapsulation does not mean the product is in a capsule: it means that the product mass has been coated with either an alginate, cellulose, chitosan, or pectin.  Some companies do use xanthan gum, starch, carrgeenan, or gelatin.  Check with the manufacturer to find out specifically what kind of microencapsulation is used.

BioStar’s BioFlora EQ
BioStar was one of the equine supplement companies to introduce a multi-strain probiotic product with the strain L.rhamnosus in our formula BioFlora EQ.  We are also one of the first equine supplement companies to use microencapsulation for our probiotic formulas, and ensure a minimum of 100 billion CFUs per teaspoon.

BioFlora EQ | BioStar US

The microorganisms in BioFlora EQ are made by a small Canadian company, run by a microbiologist who specializes in small, customized batches which we receive monthly.  This is important because, over time, even encapsulated microorganisms can start to degrade.  Virtually every bottle of BioFlora EQ that gets shipped to our customers is no more than 30 days old, with a best-by date of 6 months from the time of bottling.


L. rhamnosus is not a panacea, but it is an important therapeutic microorganism for the immune and respiratory systems.



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