The Equine Microbiome

The horse’s microbiome consists of the microorganisms, bacteria, fungi along with their interactions and functions in the horse’s digestive system.

The upper digestive tract, stomach and small intestine is mostly populated by organisms that break down and ferment starch and simple carbohydrates. These functions are important as they reduce the amount of glucose available to the horse and limit the carbohydrates that enter the large intestine.

The horse’s large intestine is where most of the organisms live, it is host to an incredibly diverse range of microflora which is responsible for a myriad of health and life sustaining activities. Its health and function are critical to normal digestive function.

What does the research say?

Both Human and Veterinary researchers are investigating the depths of the digestive system. Studies in Humans and other animals are slowly uncovering the mysteries however species-specific research in the horse is lacking.

Because horses are hindgut fermenters, its extremely important to study the microbiome, changes to the microbial environment can lead to some of the most common equine health conditions such as colic, colitis and laminitis, and further study in the area is crucial for treatment and prevention.

What research has determined so far is that each horses microbiome is unique and adapted to each individual horse and is responsible for:

✅  Breakdown of sugars, starch, carbohydrates, fibre and protein

✅  Boosting the body’s immune system and directing activity of immune cells

✅  Encourage production of protective mucous in the gut

✅  Reduced inflammation and allergy related compounds

✅  Fibre fermentation to produce short-chain fatty acids used for energy generation

✅  Producing antimicrobial products to protect against pathogenic microbes

✅  Physically excluding pathogens

✅  Inhibiting the absorption of bacterial toxins

The environment is symbiotic which means that the organisms work together and rely on each other for their needs. For example, some organisms ferment starch to lactate and others use the lactate which goes on to have a buffering effect on the intestines.

When a foal is first born its intestines have essentially developed in a sterile environment (the placenta). Research has shown that by the time a foal is 60 days old it’s been colonized by a full array of microorganisms’ equivalent to an adult horse. A foal’s microbiome develops from the birthing process, in nursing, eating grass and other foods, consuming carbohydrates and from the practice of eating faeces.

Research is also showing that in particular feeding regimes and disease states there is a corresponding change to the composition of the microbiome. For example, a change from a forage-based diet to a concentrate-based diet induces a rise in the lactic acid producing organisms and changes the composition of the species.

They have also identified that the composition and makeup of the microbiome is significantly less diverse in horses with diarrhea and also in that of domesticated horses when compare to their wild counterparts.

Even though the research in horses is lacking it seems obvious that attention to a healthy microbiome is extremely important to maintain good health.