Page 656 - Clinical Small Animal Internal Medicine

624 Section 6 Gastrointestinal Disease

together to add a growth substrate for the administered of products did not list any information about the organ-
VetBooks.ir probiotic. Prebiotics are nondigestible food ingredients isms (i.e., did not provide the strain designation) and
their numbers. Also most products did not contain the
(e.g., fructooligosaccharides [FOS] and galactooligosac-
charides [GOS]) that are added to diets to stimulate the
recommended to only select probiotic products that
growth of native probiotic bacteria. Prebiotics are typi- stated numbers of bacteria. Therefore, at this point it is
cally added to diets to enhance the growth of endoge- have clinical and published data behind them.
nous microorganisms or stimulate their metabolism. There are only a few probiotic strains with extensive in
The target groups for prebiotic administration, for exam- vitro as well as clinical data (mostly in humans) published
ple Bifidobacterium spp., were believed to be major bac- in primary literature (e.g. VSL#3 strains, Lactobacillus
terial groups in the canine and feline GI tract before the GG, E. coli Nissle, Saccharomyces boulardii). There are
advent of molecular studies. However, only minor data available based on clinical studies in veterinary
changes in microbiota are typically induced through patients for the following products: Enterococcus fae-
prebiotics, as the administered compounds fulfill only cium SF68 (Fortiflora®), Visbiome®, SIVOY®, and
some of the nutrient requirements for their target Proviable®.
bacteria, and other essential nutrients remain at growth‐ Currently, selection of bacterial strains for most com-
limiting amounts. In addition, because of the individual- mercial probiotic products is mostly based on their
ity of the microbiota, not every animal will have the same ability to survive the passage through the stomach and
bacterial strains and enzymes that are needed to utilize small intestine, their ability to adhere to mucus, and in
the administered prebiotics. Therefore, only a portion of vitro immunomodulation. Furthermore, strains are
animals will respond with increases in the targeted selected that are on the safety list of the FDA, as these are
bacterial groups. It is also unclear whether the bacterial approved for human and animal use, and no additional
groups necessary for prebiotic utilization are present in safety data are necessary. These strains are typically
animals with dysbiosis. Consequently, there are no pub- lactic acid bacteria (Lactobacillus, Bifidobacterium,
lished clinical studies that have evaluated prebiotics in Enterococcus, Streptococcus), as these bacterial genera
animals with GI disease. were traditionally believed to confer health benefits.
Prebiotics may be useful in stimulating the microbiota However, due to the complexity of the microbiota, there
and immune system in healthy animals, but their benefit is no clear correlation between changes in these bacterial
in animals with GI disease has not been widely explored. groups and health and disease. While lactic acid bacteria
In contrast, more clinical data are available about probi- are still the most commonly used probiotic strains, in the
otics (or synbiotics), and this will be discussed in more future novel products may become available containing
detail below. bacterial groups that are more abundant and depleted in
GI disease (e.g., Faecalibacterium, Blautia, etc.).
The actual mechanisms through which probiotic
Selection of Probiotics
strains can elucidate beneficial effects are numerous.
The intestinal microbiota is an important modulator of Some probiotic strains have been shown to modulate the
the immune system. Administration of specific bacterial immune system, such as enhancing IgA production and
strains as probiotics can potentially mimic the effects of pathogen phagocytosis and stimulating release of antiin-
the normal microbiome. It is important that the clinician flammatory cytokines. Other probiotic strains help to
and client understand that every bacterial strain may restore mucosal barrier function. Probiotics can also
differ substantially in its functional and immunologic help protect the host from pathogenic bacteria through
properties. Therefore, not every strain will elicit the the production of antimicrobial substances, and through
same response, and ideally strains are selected for the competitive exclusion of pathogens by preventing
right disease and the right patient based on clinical stud- adhesion, occupying binding sites, or consuming vital
ies. Information regarding strain designations is criti- nutrients.
cally important in clinical studies, to be able to select the While often probiotics are believed to modulate the
proper product containing the clinically tested strain. intestinal microbiota, recent studies suggest that they
However, in veterinary practice there are few clinical have no appreciable effect on the overall composition of
data available. There are many commercial products the intestinal microbiota, as only minor changes were
available containing various strains that have not been observed in fecal samples in healthy as well as diseased
tested in clinical studies. dogs. Rather than changing the entire microbiota, some
In the US, probiotics are considered to be nutritional strains may adhere to the mucosa and directly communi-
supplements and, therefore undergo little regulatory cate with the immune system; this has been shown for
scrutiny. Unfortunately, many commercial products lack Visbiome strains in dogs with IBD. In order to impart a
acceptable quality. For example, in one study almost 50% health benefit to the host, a probiotic must be able to