Hello, I'm Doctor Alicia Long, and today I'm gonna be talking with you about colic and the equine intestinal microbiota. So, what we're gonna go over today, is mostly kind of geared towards, understanding a little bit about kind of how we research and talk about the microbiome in general. Especially kind of in a try to help you if you're reading any sort of primary literature about the topic, kind of how the data is presented and, and everything to make it a little bit more understandable.
And then we'll also go into a little bit about what we know about the normal equine, intestinal microbiota, the sort of small amount that we know about equine colic and the intestinal microbiota. And then sort of where do we go from here and kind of what are some future things that we need to try to learn since this still is relatively an emerging kind of field of study for us and and understanding. So these are our learning objectives, so again, we'll go through kind of each of these, but, you know, some of the main kind of points that I want to hit on are sort of again, how we talk about and analyse the microbiome, you know, how the normal equine intestinal microbiome looks based on different parts of the intestinal tract.
Again, comparing the microbiome and horses with colic versus those without. And so, you know, talk a little bit about different types of colic and then a little bit touch on, you know, kind of maybe how this would lead to sort of treatment and intervention specifically kind of looking at faecal microbiota transplantation. So just a little bit overview of terminology, again these are words that you'll probably see kind of over here talking about the microbiome.
So when we talk about microbiota versus microbiome, a lot of times these terms are used interchangeably and you know, for the most part it doesn't, you know, totally matter the difference when you're just kind of thinking about it, but there are a little bit of differences. So microbiota technically refers to the microorganisms or members of a particular environment. For instance, talking about the bacteria, you know, protozoa viruses in the GI tract.
The microbiome really refers to kind of how those microorganisms and their DNA RNA interact with the environment. So kind of not only just the bacteria or the, you know, microorganisms, but how they interact with the environment that they're in and, and kind of how that plays into the overall community. So then when we talk specifically about the terms of how we again assess the microbiome and describe it, we use terms like alpha diversity and beta diversity, which again, the alpha diversity is looking at the characteristics of an individual group or sample.
So it's, you know, based on statistical methods and analysis, and we talk about things like richness, evenness, and, and diversity. Beta diversity is again a way to statistically evaluate the microbiota, and this is though comparing different bacterial communities between groups or samples. So again, instead of just what's in the individual, how do they compare to other populations environment samples.
Relative abundance is where we look at the numbers of bacteria that are there, but again, this is not an absolute count. This is a percentage of the population that a specific microorganism encompasses. So again, basically, you know, is it of the 100% of all the bacteria that are there, how much percentage of the population does a certain bacteria make up, whether you're talking about the yin level, the genus, the species, whatever.
So again, just a little bit of review remember because we'll use these words a little bit ylum is kind of our, you know, top of our taxonomic classification and then we go all the way down to genus and species which is Usually sort of how we refer to most bacteria in our, in our kind of practising day. When we're looking at the microbiome, we usually talk mostly in phylum or genus, but certainly there are other ways to describe it and, and some types of analysis can, can also look at the species level. So again, we're gonna kind of focus on these three terms, because this is how a lot of the, you know, data and analysis is presented, so I just wanna kind of review these for you all so that you can sort of understand what these terms mean when, when they're being discussed.
So again, alpha diversity is looking at the specific, you know, bacteria here we're talking about theoretically also protozo or a virus, so most of the time we're talking about bacteria, but any microorganisms, so assessing the members of a specific population, for instance, each of these circles might be looking at the faecal microbiome from an individual horse, right? You think horse 1, horse 2, horse 3. And this looks at things like richness, which again is just the absolute number of groups.
So again, in this example here in the top left population, you would see that there are 3 different groups of species, right, the giraffes, the kangaroos, the sloths. So again, that would have maybe the riches of 3 versus over in the top right, you'd be looking at 2, right, 2 different species there. And then even this is a kind of a relative distribution of each taxonomic group.
So basically which groups dominate in numbers. So again, you know, in, in one in the top right there, you have just largely kind of, you know, unicorn, numbers versus loss. So again, maybe less, you know, or kind of a more evenness where there's more of one that's abundant over the others.
So again, mostly just remember that alpha diversity looks at the analysis of the types of species number of species, different species that are within one single population and tries to describe their characteristics. And so then again, beta diversity is you're actually measuring the dissimilarity, so how different two different populations, samples, whatever are. So for instance, if these are each representing the faecal, you know, sample of a horse, horse 12, horse 3, you could then talk about the differences between the horses so how dissimilar they are.
So again, you know, one of them had only one group has unicorns, and so that would make it pretty different than the other two when you're kind of comparing them. And so then when relative abundance again this is the percentage of the population that each taxonomic group occupies. So over in the, you know, horse, for instance on the left, you would say sloths are 50%, kangaroos are 30%, giraffes are 20%, over on the right, those sloths are only 25%, right?
So in that group sloths would have a relative abundance in that population on the top right than in the population on the top left. So relative abundance again, remember it's not an absolute number. If you have an increase or decrease in one type of species, it would affect the relative abundance of the other, right?
So these are things that we analyse, but remembering that it's part of a total population, a total of 100%, and how they kind of, you know, change in relative numbers to each other. So when we talk about how we evaluate the intestinal microbiome, there's different ways that we can do this, you know, kind of the more sort of standard way would be culture-based techniques, you know, where you, you know, collect a sample, put it on a culture plate and grow it. The problem is that most intestinal bacteria are pretty difficult to grow with just basic culture techniques, especially anaerobic bacteria.
You know, those are a bit more slow growing, harder to kind of really, you know, isolate and, and, increase their growth, and you can only really assess bacteria in some fungi, right? We can't culture necessarily, you know, it's a typical culture plate where you would look at viruses or protozoa, but those are also important members of our intestinal microbiome. So culture-based techniques are certainly kind of the foundation of where we start looking at this, but more and more we are, you know, using these less and, and moving over to these kind of genomic-based techniques.
So there's sequencing, which is really kind of the the base of what we use, and with sequencing again you're sequencing the genome of the of whatever is in the sample. There are two different types. There's metagenomic or shotgun sequencing, which is where you look at all of the DNA that's present in the sample, so you pick up every little bit, .
This will produce a large amount of data and definitely is something that is more up and coming and overall in our veterinary species, but you know, does produce a large amount of data and can take a lot more kind of post analysis of the sequencing to understand sort of what that data means but certainly provides a lot of useful information. What we mostly use though is this targeted amplicon or 16SR RNA sequencing. So again, when you look at a lot of the studies that are in horses, it will be on the 16S sequencing and what this uses is a specific conserved region of the gene that is present in all bacteria to identify what bacteria are there.
And then with additional sequencing, you can figure out which specific. Species genome, sorry, genome or phyla are there. So again, you just kind of a targeted one.
It gives you, you know, sort of an information about, you know, what is there, what's present. So this is mostly what we look at, in most of our current studies, although metagenomics is becoming more popular than QPCR again, some of the other types of PCR, this, is something that is used in some studies, although it's not kind of the standard one that we focus on, so we don't talk about this too much, but Again with the sequencing here, this is where we're talking about the alpha and beta diversity and relative abundance measures. The PCR, one of the benefits of that is you can get actually absolute abundance data.
So again, you're actually counting how many of different taxs are there versus the relative abundance, which again is sort of a comparative proportion of the population. So, it gives you a little bit of different information, but most of our studies again use this 16SR RNA sequencing. All right, so that was kind of a summary of again some of the terminology that we use and sort of just a little bit of info of how we assess the microbiome.
So now we'll go into kind of what we know about the normal, quote unquote normal intestinal microbiota, and basically some of the questions that these are kind of, you know, studies have tried to answer and sort of what we've tried to figure out in the horse is sort of is there a common core microbiota of the equine intestinal tract. So again, if you look at horses that are out there in the world, quote unquote normal horses, right, healthy horses, is there sort of a common gut microbiota, gut bacteria population that we see among all horses and also, you know, how do the different GI compartments compare to each other. We know that different parts of the intestines have very different functions.
So, you know, one of the things that, you know, these studies have tried to answer is do they have differences between each other? And the answer is that yes, there seems to be a common core kind of microbiota gut bacteria of the equine intestinal tract. Although it is definitely very individual dependent as we'll talk about, and there are definitely differences between various parts of the GI tract that you see going from kind of oral to more a oral.
So, I'm in the fore gut, remember, so before we get to the hindgut of the horse, the stomach and small intestine, this is where starch, soluble sugars, readily fermentable fibre and proteins and amino acids are used as energy sources and substrates for energy production. And so the main acids that are produced in this for stomach of the horse are lactate and acetate. And so a lot of the bacteria that we see here are lactate producing bacteria that will break down these types of substrates, as well as obviously the intestine themselves doing some of the digestion, right?
But in the stomach, we see over here on the left, again, these are just numbers looking at relative abundance. So you'll see that 100 means 100%, right? So that's the total, number of bacteria, the total percentage of bacteria that are there.
And along the x-axis is a different type of bacteria phyla, so the major groups of bacteria, and how much of that abundance they make up. So in the stomach, you'll see that over on the left there, it's dominated by Fermacudes and proteobacteria and then bacteroides, and proteobacteria are those really heavy lactate producing bacteria. So you see that they're in much higher numbers in the stomach and small intestine than some of the other groups, might be, although also Fermacues is certainly high up there too, which are the fibre digesters.
And so from the summit to the ileum you see that there's a decrease in the bacteroides and an increase in proteobacteria, again, more of that lactate producing bacteria. And so then, in the hindgut as you move aborally, so looking at the secum in the colon, there are definitely a greater number of different bacteria that make up the overall microbiota. You can see here, there's more kind of phylo that are discussed.
And so overall, we would say that the hindgut has kind of an increased diversity of bacteria that are present compared to the fore gut. Remember that in the hindgut, the main substrate for bacteria are complex carbohydrates that have not been digested in the upper GI tract. And so the bacteria that live here help with digeststion of that, right?
That's our main job. And so, they're mainly strict anaerobes, and they, through fermentation, produce these short chain fatty acids that we talk about. So acetate, butyrate and propionate.
And in the hindgut of the horse, remember that lactate production should be very low in health. So in a normal healthy horse, you can see that pink proteobacteria has a much smaller relative abundance than it did. In the fore gut, and that's because again lactate production should be much lower in this area.
And we have, again, several additional filo that are introduced here but still predominated by Fermacues and bacteroides, overall. There are also you can see again some other popular important players of recommicrobia, spirochetes, fibrobacteries, and actinobacteria. Those are all important ones as well.
Remember, again, like I said, the proteobacteria low abundance in the hind gut. And what's important to note here is if you look at the spec or the genus that are listed underneath the graph, to kind of say what are the common genuss that are genera that are there, Clotridiales, which used to be called Clostridium. Are, important members of the microbiome and healthy horses, so we always talk about Clostridium is sort of a disease forming thing, but in horses actually Clostridium are a really important part of the normal microbiota of healthy horses.
And so if you look at this kind of here, you'll see that when you look at the faecal microbiota, it's relatively similar to the colonic and you know, somewhat faecal but especially colonic microbiota. And so what's nice about this is that this means that we can use faecal microbiota, so collecting faeces and looking at the microbiota there as a way to assess the overall hindgut. So again, it's a nice kind of surrogate, which is useful because again, faeces is obviously much less invasive to collect for studies, than within the colon.
So you'll see that we talk about the faecal microbiota a lot and studies as kind of a surrogate for this hindgut microbiota. Remember though, that changes in the faeces will be delayed temporally compared to changes in the colon, right, because of the transit time of ingesta. So if you have something that changes the colonic microbiota, you know, it will probably take anywhere from 1 to maybe even 3 days to see a change in the faeces, because, of the, the transit time of, of the ingesta.
So in this chart here, this is looking at the faecal microbiota, and again this is a summary of, you know, kind of some of the main studies that have been done looking at the faecal microbiota and healthy horses, and this is looking at the relative abundance. So again it's a bar graph on the left is the percentage of the total going up to 100%. And then across the x-axis is all the different studies, and you can see the different colours are for the different phylum that are there.
So again, as we said before, ermicues is the major phylum of the equine hindgut, but in, you know, we can see that in these studies, depending on the study we're looking at either bacteroides, which is red, or verruo microbibia, which is green, are kind of the second highest relative abundance, and we think this probably has to do with sort of study design and what type of analysis is used. And so, this is something that we also have to investigate in horses that, you know, kind of what is the ideal study analysis or analysis method and sequencing method to look at VCs, but those top three Fermacuess, bacteroids, and verruca microbi are kind of the top 3 that we see in equine specs. Certainly between the studies, there's a variation, those less abundant phyla, you can see the kind of smaller colours there.
But, one thing that all of these studies have seen when you look at the kind of individual data is that the faecal microbiota and really the intestinal microbiota is quite different between individual and is influenced by different factors such as geography, diet, you know, kind of definitely diet plays a large role in all of that. So, definitely lots of individual variation. And so, again, kind of as a summary of what the normal intestinal microbiota is.
Remember that the forgot and the hindgut had definitely have a difference in their microbiota. Fermacues is a dominant phylum in both, but, in the hindgut there should be minimal of those lactate producing bacteria, in the normal hindgut, whereas they're much higher in the fore gut. Faecal microbiota can be used as a surrogate for colonic microbiota, and we're doing our studies, that's a lot of the reasons that we're using faeces is to try to use as a surrogate for looking at the colon and, and kind of, you know, the, the living horse.
And really, really important is that there's significant inter-animal variation. And so, a lot of the studies will show that that is something that affects the, the results a lot. That is sort of each individual horse's variation.
Studies often focus on the taxonomic groups of the highest relative abundance. So again, we talked about Fermacues, bacteroides, verruco microbia, proteobacteria, but minimally abundant groups are also important and and need to not be forgotten when we're assessing and, and those can be definitely very different based on, based on different disease or health states. And here it's important to remember that I've been talking about adults, so this is all about related to the adult microbiome.
Foals have a different intestinal microbiome at a younger age and then gradually transition to similar to the adult after a few months of age, and there are definitely studies that have shown kind of how that transition happens. All right, so, now we'll kind of go into what we know about the faecal microbiota and colic, and, as I said before, the data that we have is really quite minimal overall considering, sort of how important colic is in horses and, and how much we know the bacteria probably play a role. We're still relatively early in our, in our kind of data and analysis of this on horses, but we'll go through the studies that that have been done, mainly up until this date.
So one of the earlier studies that looked at the faecal microbio and colic was in 2015 using three farms in central Kentucky, and basically their goal was to look at the faecal microbiota in mares, brood mares, those that developed colic and those that didn't. So they used 13 mares that were. Pregnant that developed colic, 13 mares that did not display signs of colic, and 5 non-pregnant controls.
These are all thoroughbred mares. You can see here the types of colic that were displayed, large colon boullu and just colonic colics in general were pretty high up there, and then a case of enterocolitis. They got faecal samples, both pre and postpartum, and again they use the 16S gene sequencing.
So, some of the things they found, the microbiota from late-term pregnant mares was different from non-pregnant mares, but, you know, the, there was limited impact in the short term of foline on the faecal microbitum postpartum, so basically the, the faecal microbi didn't change significantly right after foline from pre-foline. And so this, you know, this graph here is again showing the relative abundance of on the left horses who and up to 1, which is, you know, you can think of as 100%, but a total of 1. So on the left is a control group, horses that did not develop colic, and horses, .
That had large colon volvulus, and so basically compared to the age and time match controls, the faecal samples immediately before the colic episode and those four horses from the mares that developed large colon volvulus had significant differences in their bacterial composition compared to mares that did not develop large colon volvulus. So there was a difference preceding even the colic episode in their faecal microbiome. You can see in the chart, how many large colonvolvulle smears, the Proteobacter group, so that kind of like dark purple blue was much higher in relative abundance than in the horses that didn't develop colic.
And remember that we said that again this violet should normally be present in low numbers in healthy horses, and concurrently we saw a decrease in the number of fermacudes in those horses as that proteobacter increased. So certainly some changes preceding colic that again maybe could be, you know, something used to try to assess when colic might happen or try try to intervene before it does. Here is looking at kind of a a relative abundance sort of numbers.
So the control horses on the right, large cobos on the left, these are populations that were significantly different between the two groups, and horses that did not develop colic, again those control horses had several different taxonomic groups, so some genera that were significantly different where that did develop colic. And so right here you can see again such as the lacnose braci and the Ruinococcus. These are quite different than the large co globuo sms.
So again, are these populations that we could use based on these studies to try to target or protect these groups to sort of maintain how these resources and try to prevent colic. Certainly we're a long way off from knowing exactly which ones to intervene with, but those are some of the trends that we look forward to try to say, you know, kind of how could we intervene. So another study out of in 2019, that looked at horses that were presented to a referral hospital.
So, again, you know, not out in the field, and compared horses that presented for colic, compared to those that presented for an elective surgical procedure. So again, the elective surgical procedure horses, theoretically, no GI disease, no history of that, you know, otherwise healthy, besides their sort of, you know, you know, elective surgical condition. So they could have had 17 horses that presented for colic and 30 horses presenting for elective procedures.
Of the colic horses, 8 were surgical colic cases here, again, large colon volvulus, you know, left dorsal displacement, small intestinal lesions, and then 9 medical colics again, nephrosplenic or left dorsal displacement, other displacements, impactions, things like that. They had various breeds, they took admission faecal samples from the colics and elective cases and analysed you again using the 16S RNA gene sequencing. So, looking here at alpha and beta diversity, so on the left is the alpha diversity, and at the top, you're looking at the number of species, so species richness, and then on the bottom is sort of this diversity.
And basically they're plotted on the graphs on the left is the elective cases. On the right is the colic, a left and elective and colic on the bottom as well. And the kind of number absolute kind of measure of diversity is up on the y axis.
So we can see that as compared to horses that presented for elective surgical procedures, the horses presented for colic had fewer species and lower diversity than those elective cases. So definitely a significant difference between those two groups and sort of, you know, they had decreased diversity, . And fewer species overall present or fewer taxa overall present.
And then in the beta diversity, we can also see on the right there. So basically in these plots, the reds are the elective, the blue or the colic, and what these plots show us is they sort of cluster based on, you know, similarities or differences. So the closer two dots are together, the more similar they are.
The further apart, the more different they are. So if you just sort of overall look at the red compared to the blue. You can see that in both the graphs, the red tend to group more towards each other.
So on the top one, kind of more to the bottom right, in the lower land more to the upper right, whereas the cola cases tend to group more together to the left, lower or left upper. So again, what this shows us is that there was a difference in the overall bacterial community composition between elective and cola cases. And then looking at relative abundance, horses presented for colic had reduced number of known commensal bacteria.
So for instance, Clostridia, that's in the graph on the right there. You can see the colic had a lower relative abundance of those than the elective, and increased relative proportion of bacteria whose growth is favoured when there's disturbances in the gut. So for instance, we know this happened the streptococcus on the graph on the left there.
So, elective cases had less of that, colic overall had more, . There's some overlaps on the graph, and again, that's due to individual variation between the horses, but the trends are there for colic versus elective. So it seems like overall colic cases, you know, had lower diversity and richness and different bacterial community populations and horses that didn't have colic.
Using the same group of horses, those 17 horses that presented for colic, the authors did a later study that tried to compare within those colic horses, looking at differences based on the type of colic, as well as the duration of colic. And so again, same, same. Polic cases, they used here admission samples as well as day one after admission and day 3 are discharged.
So basically, if they left before day 3, they would get it then if they left at day 3, that's when they took their samples. So multiple samples during the time they were in hospital. And again, just kind of as a summary here, they had surgical colics, medical colics, both large intestine and small intestinal disease, and then the duration of colic was split into those that were colicky for had colic signs for more than 60 hours before they presented, or more acute colic, which is less than 60 hours before they're presented to the hospital.
And so here again, alpha diversity image on the left, beta diversity on the right. Over here on the left and the right, they're comparing based on the duration of colic. So again, horses that had less than 60 or greater than or equal to 60.
So in the alpha diversity graphs, you can see that horses that had a longer duration of colic had a decreased species richness and diversity. So again, their overall numbers were lower in those alpha diversity graphs, lower on the Y axis, compared to those that had shorter colic duration. So more derangements, the longer their colic was happening.
And then similarly, if you look at the beta diversity graph on the right, again, remember the dots are closer together if they're more similar, further apart if they're more different. And so there was an overall difference in the bacterial community composition and horses that had a longer collar duration than those that had shorter. And another thing that they found too is that horses that had colic for longer, so greater than 60 hours, had a lower relative abundance of Fermacudes, meaning that other types of bacteria had increased in relative abundance, you know, so some of those other populations.
So they found also a significant difference in some of those bacteria that were present when comparing large intestinal versus small intestinal lesions. And in the large intestinal lesions would certainly right, a lot of these are we're focusing sort of on the hind gut. Again, they had those decreased commensal bacteria, the los.
Through minococcate Lactobacillus and increased in certain things such as lacnose bra and alpha proteobacteria. So there were certainly specific populations or specific type of bacteria that seemed to change related to the colic and specifically the large intestinal. And actually the small intestine saw an opposite trend.
So seems to be some difference based on forgot versus hindgut, which makes sense, you know, in some ways as we talked about that they start with a different type of population in general, so disturbances would probably cause different trends. So definitely some differences seen in the type of bacteria that was there based on the type of colic. So a different group again compared horses that had colic to quote unquote healthy horses.
This study looked at horses that presented to the hospital for colic and compared them with healthy horses that were in farms local to the hospital. These are all thoroughbred horses, and for the colic cases they took samples at admission, and for the other horses they were just a single time point on the farm. So again, alpha diversity here on the top, beta diversity on the bottom, again, alpha diversity, you're looking at the overall richness and diversity numbers.
And so horses with colic had both decreased species richness and evenness again, you know, similar to the previous studies with colic again, definitely changes the with these diversity measures and decreased diversity in horses with colic. Also, as we see in the Bottom, as based on the grouping of the dots, horses with colic again had different community compositions, a different composition of the bacteria than healthy horses. And in this study, they found that the small intestinal lesions were more dissimilar from the healthy horses than the large intestinal lesions.
And so this is some of the relative abundance comparison again, if you look over on the left, they're comparing large colon or large intestine to the healthy horses. So large colon on the left is in red, healthy horses in green, small small sorry, small intestinal colic or SC, small intestine, and the HH in green is a healthy horses over on the right. So again, in colic they found increased level ofermacues in colic horses compared to healthy.
And also they found that, you know, there were differences in changes in the bacteria in the large intestinal colic, specifically, they had an increased lactate acid producing bacteria compared to healthy horses, so the, lactobacilia species and in the small intestinal colic, they had increased streptococcus, which if you remember from Some of the previous studies, we also saw that there. So definitely, you know, between these studies, they're using different populations, different types of colic and all that, but they still are finding sort of overall similar trends as far as some of the changes with those increased lactate producing bacteria, lactic acid-producing bacteria in the colic cases. So one of the, you know, kind of, .
You know, to sort of summarise what we talked about, one of the challenges with looking at the intestinal microbi and now the overall. Have a limited number of studies. So there's really just a handful of studies that have looked at this, and within each of those studies, the sample sizes are relatively small, you know, again, not more than several dozen horses, and they have varying types of colic.
And remembering that's what's really tricky with these small sample sizes, as we talked about there's lots of individual horse variation, and so that really largely affects some of the results from these studies when they have small sample sizes, the individual horse factor or horse effect can kind of override. Some of the other things that we see. So definitely some limitations that we have with the current studies.
But, you know, we definitely have some really useful data from what we've known so far. And so when you're thinking about kind of the intestinal microbio and colic, what we do know is that there certainly is a decreased diversity in horses with colic and also decreased richness. So that alpha and beta diversity, there's, there's sort of that alpha diversity with diversity and richness, there's definitely a decrease in that in horses with colic.
And also there's this different composition of bacteria, right? So we see that with the beta diversity. They have again compared between communities differences between horses with colic and those without.
And looking at the relative abundance, we see that different, you know, different phyla, different genera, different types of bacteria will change in relative abundance between the colic and healthies. And so one of the kind of summaries is again, we see a decrease in mental bacteria such as lostridiales and an increase in these bacteria that are, you know, more prevalent when the gut goes through disturbance such as streptococcus. So those are, you know, trends that we can kind of summarise based on a few of the studies.
We also saw with the studies that there were differences based on the duration of colic, so horses who have colic for longer will have seem to have more changes in their microbiome than horses that are more acute, which again would make sense. And based on some of that work done with the brood mares in Kentucky, these changes do seem to precede the colic episode, at least in those cases, right? It was only 4 horses, but certainly those horses had a difference in their bacteria that was found even before they developed their large colon volvulus or their colic.
So it certainly seems like there is some change that happens before we see the clinical signs and the really true kind of incidence of the actual colic episode. Overall, we definitely see a trend for an increase in lactate producing bacteria in the hindgut of horses with colic, which as we talked about, should be relatively low in numbers comparatively, but in colic, these seem to increase in numbers. And so, you know, again, some of the kind of challenges that we face with we answer our questions about the intestinal microbiota disease is, you know, what is the difference between correlation and causation.
So again, is it that the gut bacteria changes and then colic develops, right? So is there something that disturbs the bacteria that allows for the colic to happen, or is it simply that the colic is happening for whatever reason and then the gut bacteria changes because there's a change in the environment and so the bacterial populations change. You know, at this point, we haven't been able to prove causation, in multiple studies.
Again, the study out of Kentucky look at the brood mares certainly suggests a causation and that the bacterial change happened before, but, all other studies really have just been looking at correlation. So there definitely needs to be more work done into, to again, you know, if is the change of bacteria really causing colic. And, you know, this begs the question if there is a causation, right?
So if changes in the bacteria are what caused the colic to happen, can altering a patient's intestinal microbiota treat or cure certain diseases, right? Could we intervene by trying to alter the microbiota, before something happens, is that, you know, have disturbances and therefore try to prevent, you know, an actual colic episode. So those are all, you know, kind of sort of overarching questions.
We're really sort of where do we go from here? And so, like I said, as we kind of summarise, there's a lot that we don't know. Really, we need to do studies with larger sample sizes, in horses with colic so that we can try to, you know, overcome that significant effect of inter-animal variation.
So that's something that we'll have to try to, to, you know, encourage for future studies. And again, how do we prove or disprove causation? I think a lot of this is gonna be if we can try to get samples from horses before they have colic, which obviously is difficult, right?
Cause you can't predict when colic is gonna happen, but that would certainly be something that we need to try to do is again prove if there's causation because, you know, if we can prove that changes in bacteria cause. Maybe not all types of colic, but maybe some types of colic. Then that would allow us to try to intervene to again, you know, improve animal health, right, and prevent colic from happening or at least, you know, the variety of colic.
So ways that we can intervene, could we manipulate the diet? You know, we know that diet relates to microbiome a lot and so could we alter diet to try to prevent certain types of colic. Are there different management practises that we can do to, to try to prevent colic from happening in horses.
Pre-y probiotics are certainly something that are used by many, many horse owners, to try to overall maintain gut health, and, you know, this is largely based on human pre probiotics. What I will say is that this is certainly an attractive option, right? If you can give a pill, a supplement, a powder, to kind of protect and support the microbiome.
Unfortunately, a lot of these pre or probiotics, well, you know, none of them are under FDA regulation, and so, neither in human or veterinary species. And so there is no oversight of the products themselves. And so I would caution that at this point, we don't have enough.
To know what is the best bacteria to put in a pre probiotic and so there, you know, is potential that what we're giving for pre probiotics are not working or even theoretically could be causing harm because we know that some bacteria when they increase in number would be harmful potentially based on the, the data we have, and so While, you know, there are lots of products out there, I would sort of, you know, encourage kind of careful thought of what's in them and, and kind of, you know, do we have support for their use, and unfortunately, we really probably don't, hopefully that will change. But, you know, certainly many owners and veterinarians and, and even myself, right, feel that anecdotally some of them work, so there's probably something there, unfortunately, we just don't have any data to back it up yet. So, in faecal microbiota transplant, this, you know, kind of brings, an attractive alternative to maybe a single source bacteria pre probiotic, right?
So if you could take, all the bacteria that is in a normal healthy horse gut and give it to a horse, would that allow for, you know, kind of resolution of disease states, and might be more beneficial because you're giving multiple different, organisms versus just a single one that you've kind of, you know, purified and put into a product. And so, you know, to kind of go over this to summarise for those who maybe haven't heard of this, faecal microbio transplant or faecal transformation, some people will say, is the transfer of faeces from a healthy donor individual to the patient. And the goal of this is to transfer the healthy microbiota to alter the patient's gut microbiome to either treat or prevent disease.
And so what you're doing with this is you're both altering the patient's current microbiota again, trying to provide good, quote unquote good bacteria. You know, and put that in there. And also some of this good bacteria can help just by sheer number provide colonisation resistance to get pathogens, right?
So the healthy bacteria in our gut as well as in our other places in our, in our body, you know, by just living there and doing their normal work, can help, you know, prevent colonisation of bad bacteria because they're using the space and the resources. So those are kind of really the two main goals of a faecal transplant. And in humans, it's currently used as a treatment in human medicine and has, mostly for Clostridium difficile infections, so recurrent really Clostridium difficile, as well as some cases of inflammatory bowel disease and in humans it has a really high success rate in those recurrent, C diff cases, that are sort of, you know, resistant to antibiotic therapy and have had continued recurrence and faecal transplant actually has shown really great success in those cases and is, is an approved treatment.
So, you know, that's sort of where that kind of was first used and then trying to translate it over to the, to the equine or even small animal world. You know, in horses right now, there are a few studies that look at the use of faecal transplant, both in Experimental models as well as clinical cases and unfortunately, the data is really variable as far as there's really varied results with that and so in some studies it shows really good success of improving outcome, decreasing, you know, time to resolution of diarrhoea and things like that. And in other studies, it, it really doesn't show as good success.
So there's definitely still, I think, a lot to improve related to faecal transplant. And, you know, some of the challenges and questions with faecal transplant that we don't have answers for is what is the ideal donor source, what's the ideal way to prepare and store the transplant material, what's the ideal route of administration, you know, and horses we're really giving this through a nasogastric tube, but is that the best way to give it? Is there a way we can improve, you know, kind of delivery to the hindgut?
And again, what's the idea of frequency and timing of administration and and those are all things that we just don't have answers for in humans they've done some sort of systematic reviews and attempted to make kind of protocols for this, although, you know, that data is actually still not the strongest, but in horses we just really don't have specific, you know, sort of pure. Kind of, you know, data supported protocols and so most of the protocols are based off of both what is more easy logistically, as well as what has sort of anecdotally worked in various practises. So, certainly, you know, still a lot to learn, but, not to say that faecal transplant isn't an attractive and and possible thing to use in the future.
I think it's going to prove to be very promising, but still have a lot of way to go to try to make it the most effective possible and really as effective as it seems to be in human medicine. So again, circling back to the kind of probiotics because this is something that I think is important for everyone to sort of think of, so basically, there, there really just isn't great, you know, regulation oversight of these products, and a few studies have shown that actually some of these products have some things that make them maybe potential for harmful or a little bit concerning to use and so. In the study in the upper right there looking at the variability of commercial equine probiotics, none of the equine probiotics that were studied actually met their label claim of the viable microorganisms that they had, so the numbers of CFUs of of viable microorganisms.
And some several probiotics actually lacked microorganisms that were on the label. Also when, when looking at those, they found that there are bacteria listed that weren't the right names, bacteria that don't exist, you know, all those kind of things. So, unfortunately, there's a lot of, kind of, you know, the lack of oversight leads to sort of maybe lack of appropriate.
Regulation of these products that, that could make them, you know, the potential to actually be not what you're purchasing, which is not just for equine products, this is found in, in others as well. So, sort of an industry, an industry problem. And then in this other study, in looking at the antimicrobial resistant genes and probiotics, I actually found that only 94% of the products contain bacterial DNA, so some of them didn't actually have any bacterial DNA present in them, even though they claimed to have, you know, microbiota, or sorry, probiotics, good bacteria in there.
And of those that have bacteria, 97% contained at least one antimicrobial resistance gene and 82% contained two or more. So again, you know, what bacteria specific strains are being put in products and kind of how safe are they, I think it's up for questions. So I think it's just important to remember that, you know, we have a lot of unanswered questions about some of these products and I think we certainly can, can overall use them very well in the future if we, if we do some more kind of serious and controlled preparation and investigation of them, so.
And that would be the end of our top. Today, so thank you so much for your time and I hope you enjoyed it.
