Probiotics and Pet Health
Lark Burnham, Ph.D., Animal
Microflora and the
The gastrointestinal tract (GIT)
of all healthy mammals contains approximately 400 species of microflora or
microorganisms, including bacteria, yeasts, fungi and protozoa. These
microorganisms are acquired at birth from the mother, and later from the
environment, and are necessary for the health and proper functioning of the GIT.
The microflora plays an
intrinsic role in both digestion and immunology. They help degrade food,
especially in sick animals when enzymes may not secreted, convert waste material
to energy, and are the first line of defense against infection. Digestion
in mammals is a cooperative effort between enzymes secreted by the body and
endogenous microflora. Some animals do not generate the required enzymes,
as in those with exocrine pancreatic insufficiency (EPI), or lactose Intolerance
(LI). In these animals, the undigested material must then be degraded by
microorganisms in the gut.
Because conditions in the
GIT are not normal for animals with EPI and LI, they can cause the proliferation
of microorganisms that are usually found only in small numbers. These
opportunistic pathogens can cause serious problems such as diarrhea and gas, if
The endogenous microflora
also play a key role in an animal s immunological response. Infections
that enter through the GIT must first overpower the resident microflora, under
normal healthy conditions this happens only with a very large initial dose of
infectious microorganisms. However, if the animal is stressed, a smaller
number can successfully infiltrate the GIT.
Stress and the
When a mammal experiences
stress, changes in pH or the cessation of the nutrient flow can occur, killing
protective microorganisms in the body. When this happens, gaps appear in
the natural protective barrier formed by these microorganisms. Pathogens
continually pass through the GIT, but if the animal is healthy and/or the
pathogen number is low, they will pass through without doing any real damage.
Gaps in the protective barrier, however, allow pathogens opportunities to
establish themselves. Pathogens can make animals sick by simply competing
for available nutrients and starving the beneficial microorganisms, or, more
seriously, through the production of toxins. Many forms of food poisoning
involve bacterial toxins. Sometimes a very small amount of toxin can cause
an animal to become very sick or even die, and this process can occur quite
The conventional treatment
of infection is to use antibiotics, which are like nuclear bombs to bacteria -
they kill both good and bad indiscriminately. That means along with the
pathogens, many beneficial microorganisms may be killed as well, and sometimes
the target microorganisms may even survive while beneficial ones are killed.
The original antibiotics were actually derived from microorganisms by isolating
various strains of beneficial bacteria. Beneficial microorganisms pack an
assortment of biological weapons, both physical and chemical.
microorganisms possess the capacity to evolve resistance, so antibiotics can
become ineffective, pharmaceutical companies must continually search for new
antibiotics. Probiotics are microorganisms used to combat other
microorganisms, and can provide an alternative to antibiotics that rapidly
Probiotics are defined as
live microbial feed supplements which beneficially affect the host animal by
improving its microbial balance. Probiotic microorganisms, which include
bacteria, yeasts, and fungi, are good competitors and can push back pathogens
and allow the endogenous beneficial microorganisms to recover. They also
stimulate the immune system so that the body can fight more effectively.
Although probiotic microorganisms are confined to the GIT, they have
wide-reaching effects and can help control infections not located in the GIT by
activation of the immune system.
One way to think of
probiotic microorganisms, which are generally not endogenous species unless
isolated and developed for a particular species, is as armed placeholders.
They fill gaps until the endogenous microflora, decimated by antibiotics and/or
stress, can recover. Once they are back on their feet, they give the
probiotics the boot. Probiotic microorganisms usually do not attach and
become permanent residents.
Because the GIT microflora
is so varied (bacteria, yeasts, fungi and protozoa), it may require different
types of microorganisms to fill different gaps in the GIT ecology.
Different species of all types are vulnerable in differing degree to stress and
antibiotics. The best way to insure that the greatest number of gaps are
temporarily filled by probiotic microorganisms rather than opportunistic
pathogens is to use a wide-spectrum probiotic, or one that contains the widest
possible selection of different species in the required amounts. No one
probiotic species is the best in all possible scenarios. All forms of
Natur s Pet Probiotics contain similar microorganisms, just in varying amounts
depending on need.
Numbers of viable probiotic
microorganisms are crucial, both the numbers of any one species (called colony
forming units, or CFU) and numbers of different species. The numbers of
beneficial microorganisms must be superior to the invading organisms, even after
they have passed the stomach. Scientific literature recommends at least 108
(100,000,000) CFU/g or greater for treating sick animals. The state of the
animal and the intensity of the stress experienced dictates the concentration of
the probiotic the animal should receive.
Probiotic microorganisms can
be freeze-dried to retain full viability and potency until mixed with water,
which happens naturally once ingested. Some strains of bacteria are able
to go dormant if availability of nutrients and/or environmental conditions
becomes unfavorable for growth. Powdered or granulated forms must be kept
dry until fed to maintain full effectiveness. Other conditions such as
heat and sunlight can also kill probiotic microorganisms, even in the dry state.
For the longest shelf life for any probiotic, keep tightly sealed and
refrigerated. Dried forms may also be frozen once, but not repeatedly
thawed and refrozen. Freezing can extend full potency past the expiration
date. Paste and liquid probiotics must be refrigerated, and cannot be
frozen. They have a similar shelf life if kept sealed and refrigerated.
Probiotics come in at least three different concentrations:
- should be fed daily for everyday stresses such as weather and occasionally
being left alone. Usually supplied as a powder or granules.
should also be fed
daily for chronic stresses and some digestive problems.. Usually supplied
as a powder.
can be fed one or more times daily for treatment of a sick animal until the
animal is eating normally. Available in either paste or liquid.
probiotics help re-establish proper microbial balance in the GIT, it can take
from 10 to 14 days to become fully active. The more concentrated forms
start to work within just a few hours. Probiotics are safe to give even at
very high doses - they cannot be overdosed.
One common concern about
probiotics is whether they survive past the stomach. One of the most
effective probiotic microorganisms is Lactobacillus acidophilus, a Lactic
Acid-producing bacteria that actually lives in the stomach. It
prefers acid (the name means acid-lover ) and will secrete enough acid on its
own to maintain a pH uncomfortable for many opportunistic pathogens.
Research has shown that L. acidophilus generates enough acid during
nursing to postpone the secretion of hydrochloric acid in the young mammal.
microorganisms prefer the less-acidic environs of the large intestine, and will
successfully pass through the stomach and continue to the colon. There are
always some probiotic microorganisms that succumb to the extreme conditions in
the stomach, that is why the initial dose needs to be as high as it does.
This will insure that the proper number of viable microorganisms reaches their
target organs. Some probiotic products boast about special encapsulation
or other methods that are purported to by-pass the stomach. These
elaborate marketing schemes are not necessary as long as the product delivers
the minimum CFU of viable probiotic microorganisms.
Handling and storage of
probiotics can greatly influence the actual numbers of viable microorganisms
that are fed to your pet. If you buy off the shelf or from a distributor, do
you really know what you are getting? That package may indeed have had the
CFU of the various organisms listed on the label when it left the manufacturer,
but that does not mean it has that many when you actually make the purchase.
The most effective probiotics are the freshest ones, and the ones that have
spent the least time away from the manufacturer.
Illness and the
When an animal becomes ill,
the GIT is shut down and energy and other nutrients are shunted to the immune
system. Normally, there is only about a day s worth of ready energy stored
in the muscles (as glycogen, or animal sugar), and when this runs out the
metabolism must convert to burning fat. Depending on the severity or the
illness, the animal may not be able to complete the latter process. As
soon as the GIT tract shuts down, the clock starts ticking, and if the immune
system cannot defeat the infection before energy runs out, the animal will die.
Probiotic microorganisms can
metabolize food left on the GIT after it shuts down. The energy derived
from this metabolism, mainly volatile fatty acids (VFA), is readily absorbed by
the lining of the digestive tract, thus buying the animal more time.
A serious complication of
undigested food in the GIT after it shuts down is the arrival of highly
fermentable nutrients in the large intestine. This happens when sugars and
starches that would normally have been digested enzymatically are fermented in
the large intestine. Pathogenic bacteria may proliferate and cause
diarrhea, which in itself can be fatal.
Antibiotics may or may not
kill the initial invading microorganisms, and they also kill beneficial
protective microorganisms and can bring about secondary infections.
Probiotics are strongly recommended for use along with antibiotics, and at twice
the usual rate. Antibiotics can kill probiotic microorganisms, so the
doses should be staggered to maximize the benefits. Probiotics can prevent
secondary infections and may help the animal recover faster.
Any conditions that result
in a change in nutrient flow or pH can impact the viability of the endogenous
microflora. Many of these microorganisms are attached to the walls of the
GIT, nutrients come to them, and when they don t, or the pH in their niche
changes even a tenth of a point, they can die. Changes in non-GIT organs
can impact this nutrient flow and may exacerbate the initial insult. The
digestive tract, the microflora, and the immune system are all intrinsically
connected, what hurts one is going to impact the others. Very few diseases
are isolated in nature, they have repercussions throughout the animal body.
Probiotics should be
selected based on the health and stress level of the animal, and they work well
with any veterinary therapy. Both cats and dogs benefit from the regular
use of probiotics.