Probiotics for Horses
Jessica Lynn, Earth Song Ranch
Probiotic is derived from the Greek word pro meaning for and
biosis meaning life. Therefore 'pro-biotic' is, and means,
the opposite of 'anti-biotic' (against life).
Probiotics are, simply, 'live' beneficial (good) bacteria that do
their work in the digestive tract. Probiotics and digestive
enzymes can be fed as supplements to encourage the proliferation
of certain beneficial bacteria and enzymes, to work in concert
with the digestive process. There is a microbial balance that
needs to be maintained throughout the horse's digestive tract,
and though horses in the wild may naturally eat what is needed
and avoid toxins, horses in domestic situations may not. Feeding
live beneficial bacteria and digestive enzymes can help to
maintain or create microbial balance, setting up the ideal
environment for all these microorganisms to flourish, thus
enabling and optimizing digestion and maximizing the health and
well being of the animal.
Thirty years ago a horse grazing in a typical pasture would have
had the choice of approximately 30 or 40 different types of green
plants and grasses, each bringing its own specific nutrients
essential for a balanced diet, and at the same time containing
natural sources of digestive enzymes and naturally occurring
As the food passes through the stomach it enters the small intestine.
Today, in that same pasture, because of selective seeding,
fertilizing, and herbicide spraying, etc. the grazing is limited
to sometimes as few as four varieties of plants or grasses.
In this day and age, it is common that equine 'feedstuffs'
contain soybean meal, plant protein by-products, molasses and
other cereal type ingredients. These ingredients are mechanically
processed, cooked, steamed, extruded, cubed or pelleted. All the
processing coupled with extended storage often destroys essential
enzymes. From all of this over-processing, depleted/ nutrient
deficient soils, and stress, some equines are also beginning to
suffer from food enzyme deficiencies that can, by themselves,
lead to an array of non-specific related symptoms.
Your horse's stomach requires digestive enzymes to begin the process of
breaking down the feed, as only one part of the digestive
process. As that feed is then delivered to the intestinal tract,
specific types of bacteria are needed to continue the digestive
process so that the body may absorb the nutrition found in that
same food to maintain health and wellness and stay sound and
active. Digestive enzymes work with the gastric juices to start
the breakdown, then the bacteria make the feed into usable,
One of the most common sources of digestive disturbances in
horses is 'stress', which may be brought on by such things as
sudden changes, moving, competition, psychological stress of
travel and training, breeding and pregnancy, worming, parasites,
vaccines, viruses, and injury.
'Stress' can also be created by unusual or unseasonable weather
conditions, alterations in environment, and lesser quality feeds
and water. Without the proper digestive enzymes and beneficial
intestinal bacteria being in place, food passes through the
system not being able to be 'fermented' in the way it was
intended and instead of being digested remains undigested. This
undigested food passing through the gastro-intestinal tract may
then lead to situations such as colic or colic-like symptoms,
bloat, and founder, or may set up an ideal parasitic environment,
and may even increase the possibility of the horse developing
feed related allergic conditions.
Antibiotics, of course, wreak havoc by destroying bacteria in the
body indiscriminately and sometimes permanently.
The digestive system bacteria are temporarily eliminated until
they are re-introduced into the digestive tract by specific foods
or supplementation and given the chance to proliferate, flourish
and attain balance once again. Unfortunately, the microflora and
microbial balance in a horse can be upset far faster than it can
be restored; the effects may not show up immediately and may last
a long time. A horse's beneficial intestinal bacteria being
destroyed or depleted also alters the pH of this environment,
further affecting digestion and the horse's overall health and
To fully understand the role of probiotics, as well as digestive
enzymes, in your horse’s diet it is important to have a simple or
even basic understanding of the equine digestive system:
When a horse eats, his food begins an approximate 100-foot
journey through the digestive tract. Food is ground by the teeth
and mixed with enzymes in the saliva, starting the digestive
process. The food then mixes with digestive juices as it enters
the stomach. Although the stomach is relatively small compared to
the horse's size, it is one of the most important areas for
initiating the breakdown of food into utilizable nutrients using
digestive enzymes and stomach acids.
Very little absorption takes place in the stomach, with the
major part of nutrient absorption occurring via the small intestine
and a lesser amount via the cecum and large intestine.
The small intestine is the area where most soluble carbohydrates are
absorbed along with minerals, fats and proteins. Insoluble carbohydrates
that are not so easily digested, as well as any undigested soluble
carbohydrates, are then passed to the cecum, which is the
'fermentation vat' situated before the large intestine. This is
where the majority of the bacteria are found.
The purpose of the bacteria in the cecum is to break down into
viable, usable nutrients the undigested food passed from the
stomach and small intestine. A large array of bacteria/
microorganisms is needed for this to happen efficiently and
effectively. The action of these bacteria within the cecum allows
the food fibers to be broken down into volatile fatty acids that
can then be absorbed and used not only as an energy source by the
horse but to help meet his vitamin and other nutrient
requirements. (Imagine, if you will, millions of little "Pac-Man"
type creatures chomping away at the undigested feed as it is
passing through the intestinal tract.)
The purpose of the microbial fermentation process is it further
breaks out and releases the nutritional components in the
ingested feed, some of which are microbial proteins from the
digestive enzymes, along with other naturally occurring vitamin
compounds such as vitamin K and B-complex. The concept of
microbial fermentation occurs to some extent in all animals that
eat foods of plant origin, including horses and humans. Horses
(as well as some humans) depend largely or in some cases entirely
on fibrous plant materials (hays, plants, and vegetables), so
while humans rely on the stomach and large intestine, horses rely
on the cecum for the fermentation and microbial breakdown to
The population of beneficial microorganisms in the cecum remains
relatively 'stable' under 'normal' circumstances and conditions.
As long as a horse is never stressed, never needs to be wormed,
never has an abrupt change in feed, and never needs antibiotics,
then the balance should remain un-altered and remain 'stable'.
The reality is that our horses do have stressful events, do get
antibiotics occasionally, do have significant feed changes
(including each different load of hay we buy), and they will be
wormed from time to time.
There are three kinds of bacteria: 'good' (beneficial),
'neutral', and 'bad'.
The horse needs a balance of all three, but there must be enough
good to keep the bad in check. As long as the balance of good and
bad bacteria remains constant and the gastro-intestinal tract is
stable, the horse remains healthy. When the balance is upset, the
horse may eat, but may not be able to digest properly or
assimilate the nutrients he needs from his food. When this occurs
it may begin to show up as a dull coat, skin conditions,
inability to maintain weight, slow foot growth or other medical
conditions including diarrhea.