Hello. My name's Andy Gent. I'm a medicine specialist and the clinical director at Blaze Veterinary Referral Hospital, which is a a new referral hospital you may or may not be aware of, that's opening soon actually, just south of Birmingham.

And I'm gonna talk today about understanding the microbiome, which has become an incredibly topical area for us to consider over the last few years. So what are we gonna look at? Well, firstly, we're gonna look at what the microbiome is, why it's something that you should be interested in.

Secondly, we're going to consider what about the microbiome is significant in terms of the diseases that we all see, and we'll also touch a bit on some of the human diseases in which the microbiome has been shown to be beneficial or important. And then perhaps most importantly, we will look at how we can manipulate the microbiome for the benefit of our patients and also alongside that, some of the things that perhaps we need to be a bit cautious of when it comes to their impact on the microbiome. So whenever I give lectures around this topic, I in some ways have to start with an apology and say that there is a distinct possibility.

I will leave you with more questions than answers. This is very much an area where our understanding is the tip of an iceberg. We are starting to know bits and pieces, but this is a whole unknown world in terms of many of the bacteria and other organisms that live within our gut.

And so this is something that is going to be developing further over the next few years, undoubtedly, but there is lots that we don't know. So as I say, there may well be be lots of questions on the back of that. So let's start by talking about the microbiome and particularly its relation to to gut disease.

I think we're all aware that gut diseases are a very important and common presentation that we see in practise across dogs, cats, and, and of course other species as well. And we see a whole spectrum of presentations from very mildly affected dogs that, you know, have self-limiting disease to dogs like Dorothy here who have very, very severe gastrointestinal diseases, usually these kind of protein losing andropathy type diseases, and there's lots of course in between. And there's loads of manipulations that we throw at these dogs.

We might change their diets, and if we're lucky, they improve with that. We may give them other kinds of manipulations and they improve with that. Ultimately, some of them we batter with quite unpleasant drugs, so steroids or other immune suppressing drugs.

And if we give dogs with gut disease steroids, if they didn't look like Dorothy before, they probably look like her afterwards because the muscle starts dropping off them. And so I think when we manage these dogs, you know, sometimes we find manipulations that are easy and improve them quite quickly. But in many cases, the interventions can be worse than the disease.

And I think that leaves many of us questioning whether we're really managing these cases in the right way, in the best way that we can, or whether there may be a better way for us to to manage them. Maybe there may be something that we're missing. And actually many of the treatments that we use are things that have been around for years and haven't particularly evolved or changed much in in that time.

This, I think demonstrates really nicely why we should be interested in the microbiome. This is a fluorescence in situ hybridization, so a fish section through the gut. The blue staining areas is the gut wall, and we can see, of course, lots of nucleated cells that live within the gut.

The the areas that stain red are the bacteria and other organisms that live within the gut. And we can see there's an enormous number of them and that they have this intimate relationship with the wall of the gut. And so it is intuitive to think that they have to be a significant part of, you know, that area.

We know that there are roughly 10 times as many microbial cells as host cells in in mammalian bodies, and the interaction between these things is critical to the functions of our body. And for too long we've viewed these as something that we just need to kind of wipe out or other. And actually trying to understand more about the functions of these organisms, the way that they interact with our own cells, is becoming a critical part of our understanding of this area.

When there are so many of them, when their association with our own cells is so intimate, you know, I think for me it is second nature to think that this is a significant thing that we are going to have to look at. So how have we evaluated these things historically? Well, you know, if we go back a few decades, of course, really the only way that we could look at trying to evaluate the organisms within the gut was based on culture techniques.

You know, we would try and plate up on a on a petri dish and they got plate, you know, what was growing from the gut. And it was pretty crude. We would grow a whole raft of things and we were aware of the fact that there were some things that we couldn't grow.

And then I guess things evolved and we could use slightly more selective media for culturing, but ultimately our evaluation of this was pretty crude. And we know if we look at many of the organisms that we were trying to grow, actually these are things we see in normal dogs and we see in dogs with diarrhoea. We didn't really understand the role of them in many of the patients that we saw, and I think the analysis was far too crude for us to really be able to draw too many conclusions.

But times have changed. And now when we evaluate the microbiome, we can do it in a completely different way. We can take a faecal sample, we can extract the genetic material from that faecal sample.

We can sequence that. So in essence, we get a list of all of the different genetic sequences within that faecal sample, and we can then compare that to our databases of organisms to give us an idea of what's going on there. And that means that we can identify bugs that we would never be able to grow within the lab, and it gives us an idea of what species are there, at least within our knowledge of what species exist, the relative abundance of those species.

We can even look for some of the genes within those organisms. So for example, genes that code for resistance, which is, you know, a whole other discussion to have about some of these bugs. In addition to that, another area that's increased along the same time as that is using mass spectrometry to look at the metabolites of these bacteria or other organisms.

So you know, we can look at, in essence, all of the chemicals within these samples. Again, we can compare those different chemicals to our databases of chemicals, and we can work out, you know, what particular metabolites of these organisms may be there. And that can then, if we put those two things together, not only allow us to look at, you know, what the bugs that are there are, but also start to try and unpick potentially the function of some of those organisms because there's still a whole, a whole lot that we don't know about the function of those individual bugs.

And generally, we are currently focusing more on on the bacteria, but of course there's lots of other things, viruses, fungi, etc. Within the guts and and there's a, you know, a whole world of those for us to explore as well. So what do we know about the normal microbiome?

Well, there's lots of work that is done in people. And I think the fascinating thing is that actually if you look at the microbiome in different places, in in normal people. Actually, there are broad similarities between different people.

So if we look at these maps, these each vertical line in these maps represents a person. And of course, as you can see, they're in different areas of the body. And we can see that if you look at the microbiome on the skin, for example, you know, most people relatively similar.

They're the same kind of, kind of, you know, taxa of bacteria. Similar for for other areas of the body, and there can be some differences between individuals, but actually broadly there's quite a lot of similarities. Similar work done in dogs.

So this is looking at the normal microbiome of dogs. This is something called a heat map. So we can see again, each of the vertical lines here is going to represent an individual dog.

These are individual healthy dogs. The horizontal bars then represent the bacterial groups and The more red something is, the more common that is within the sample. So very red things, there's lots of, at the other end of the spectrum, blue things, there's not very much.

And if you look at healthy dogs, again, you can see that actually the normal microbiome is quite similar. There's some. Variation between individual dogs, but broadly the kind of bugs that we that that dogs have lots of, you know, we know that that's that's preserved between different dogs.

So we get some idea of what's likely to be normal, you know, what's likely to be healthy on different areas of the body. And again, you know, lots of work that hasn't been done looking at the microbiome in different places within the body, and I think there's going to be some interesting work to be done there. There's some other fascinating work when it comes to the normal microbiome looking at things that influence individuals' microbiome.

Some of this stuff in some ways is intuitive. We know that if we live with people, we are likely to have a similar microbiome. Interestingly, people who live with dogs also have many similarities in terms of their their gastrointestinal microbiome with their dogs.

Obviously we're exposed to the same environment. And so some of the, the bugs that we see will be preserved between those different, people that live together and their dogs. So what do we know about the factors that are going to influence the microbiome?

We know that your environment can have an effect. We know that your diet, particularly things like fibre, can have a huge effect on your microbiome. We know that age can have an effect, so as you get older, your microbiome tends to become less diverse, and we generally view diversity as a as a healthy feature when it comes to the microbiome.

We know that certain diseases or treatments, antibiotics being the the obviously, you know, the obvious ones, will have an impact on your microbiome. We know that your method of delivery at birth, so people who are born by a vaginal delivery, have a more diverse microbiome earlier on than people who are born by caesarean section, and there's all sorts of theories that that that may play into some of the disease risks in those different groups. We know that genetics can have, factors on this.

Nice study that's highlighted here to show that some alcohol consumption, so modest alcohol consumption, can be associated with improved diversity, and that's, you know, some of the theories around why, you know, a small amount of red wine, for example, can, can have some health benefits. Could it relate to the impact on the microbiome? Some similar work being done with other alcoholic beverages as well, showing that they can have a positive impact from a microbiome point of view.

Just to caution you, this is not a bottle of wine a day, you know, this is relatively modest amounts. But all of these things play into to influencing our microbiome. So what do we know about the microbiome in disease?

Well, again, a huge amount of work has been done looking at different microbiomes in different diseases, and actually some of the stuff that comes out of that I think is is quite staggering, quite alarming sometimes to look at how the microbiome may be able to have an impact on our health. And that is not necessarily just our gastrointestinal health. This can be health in areas that are far removed from the gut, and we'll talk about why those things may be relevant.

So probably the most obvious, you know, microbiome derangements may be associated with with gastrointestinal diseases. We know that in people, certain forms of dysbiosis are seen in people who get inflammatory bowel diseases and other types of gut disease, so IBS, celiac diseases, your risk of things like C. Difficile.

We know that immune-mediated diseases can also be associated with certain forms of dysbiosis. So, things like SLE, type one diabetes, rheumatoid arthritis, and being atopic such as asthmatics associated with certain types of derangement in your microbiome. Why might that be the case?

Well, you know, there's lots of interesting work that looks at why that could be the case. And and ultimately, all of those diseases relate to immune system dysregulation. Now we know that in normal people, your gut usually exists in, you know, this, this kind of state of anti-inflammation because you have this balance going on within your body.

So if you look at this diagram here on the left hand side, you know, this is what's kind of happening in a, in a normal person. We know that they've got lots of bugs that live within their gut. We know that there's this healthy mucus layer along the lining of the gut, which keeps a lot of those bugs away from the wall of the gut, but there's just this healthy level of interaction between the gut wall and those bacteria.

It keeps our immune system a little bit primed, but ultimately doesn't result in marked inflammation. Now we know that that mucus layer is often maintained by the end products of some of our bacterial processes that go on within our gut, particularly things that involve things like short chain fatty acids. If we see certain forms of dysbiosis.

We can get a reduction in our short chain fatty acid production. Consequently, we can get a reduction in our formation of mucus from our goblet cells along the gut. And if we lose that kind of mucus barrier, we get a lot more interaction between bacteria and the immune system within our gut wall.

The end result of that being a move towards a pro-inflammatory state, and that's not just a, you know, a local impact, that can be a systemic pro-inflammatory state. And that change from this kind of balance of prevailing anti-inflammatory towards a pro-inflammatory state is thought to, you know, underline many of the mechanisms behind this immune system dysregulation that may predispose to autoimmune disease. And so even though that change may be going on within the gut, that can then be an effect that we see outside the gut, for sure.

We know that metabolic diseases can also be associated with dysbiosis, so your risk of obesity, or risk of things like type 2 diabetes, atherosclerosis, you know, all of these things can go hand in hand with with dysbiosis. Whether these things are cause or effect is still a little bit unknown. You know, if you have significant obesity, is it that that has an impact on your gut or actually is forms of dysbiosis something that may be a factor in predisposing you to obesity in the first place?

There's a lot of work that still needs to be done with that. But we know that some of the forms of, of dysbiosis we see in these diseases may alter things like your lipid metabolism. They may have an impact on satiety.

Again, it comes back to that kind of pro-inflammatory state. So there are logical reasons why perhaps we could favour, you know, obesity in some of those states. Now an area that's become huge, of course, to look at just because of the, the impact that it has on all of us, is the role of dysbiosis in cancers.

And there's lots of information now coming out that certain forms of dysbiosis may be a risk factor for development of certain cancers. The most widely studied, the risk of colorectal cancers. And we know that certain forms of dysbiosis can favour colorectal cancer.

And some of the work that's been done looking at metabolites of bacteria gives us something of an insight into why that could be the case. We know that we can see in certain forms of dysbiosis, a reduction in some of these metabolites that potentially can have some anti-cancer effects, and we can see an increase in some of our metabolites that potentially could be carcinogenic. And so, you know, that could play a part in those risk factors.

And that may be the, you know, the linking factor that links, for example, diet and colorectal cancers. We all know that, you know, increasing the fibre intake in our diet, potentially decreases our colorectal cancer risk, you know, is the link between those two things the impact that that diet has on on our microbiome? It's certainly possible.

Other areas that are really interesting, it's also been demonstrated that with certain forms of chemotherapy, potentially some of the more modern forms of chemotherapy, such as these immunotherapy type of drugs. You can predict the response to those drugs based on your microbiome, you know, people with certain forms of dysbiosis may be less likely to respond to those treatments than people who don't have those forms of dysbiosis. So again, lots of work to be done about whether the manipulation of your microbiome could have an impact in in your response to those treatments.

Another area, you know, I think that's really fascinating because again it's far removed from the gut, is the so-called neuropsychiatric disorders. So things like autism, Alzheimer's disease, depression, Parkinson's disease, all of those seem to be associated with forms of dysbiosis. And again, there's potential ways that you can link those things through, for example, the impact on some of our neurotransmitters, you know, you know, could, and many of our neurotransmitters do come from metabolism of, of involving bacteria within the gut.

So, you know, could there be alterations in those or alterations in receptors occurring because of those forms of dysbiosis? We don't know that yet, but we know that that dysbiosis happens. And lastly, things like chronic kidney disease.

We know that certain forms of dysbiosis can have an impact on glomerular filtration, for example. And again, similar things can be seen with cirrhotic liver diseases and risk of things like hepatic encephalopathy. So there's lots of, of work that's been done.

This list increases all the time, and as I say, some of these things I think are quite scary when you start drilling down into them, that actually, you know, dysbiosis maybe is playing a huge role in our risk factor for some of these diseases. How does that occur, you know, we've touched on some of these things, reduce resistance to colonisation, you know, if you look at things like C. Difficile, we know that C.

Difficile risk can be associated with things like antibiotics. If we're given antibiotics, we've wiped out some of the bugs that are there. Maybe we have a reduced risk to colonisation directly of some of these bugs.

The dysregulation of the immune system that we've spoken about in terms of of the risk of of an inflammatory diseases, autoimmune disease. And then the big one, it's going to be the impact on the metabolism, so the altered environment, what people sometimes call postbiotics, so you know, the metabolites that live within our gut and the impact then that those can have elsewhere within our body. So we've spoken about short chain fatty acids, the role of these things with immunomodulation, and energy homeostasis, bile acid metabolites, so we know, you know, for example, bile.

Acids are metabolised by some of the bacteria within our gut. We know that in in most people that that process works effectively. If you have forms of dysbiosis, your bile acids don't get metabolised in the right way.

You may therefore have more bile acids getting into the lower parts of your gut that can stimulate things like diarrhoea, what we might call bile acid diarrhoea. So there's lots of mechanisms that may be there. So what do we know about microbiome in disease in the patients perhaps that we're more interested in?

You know, it's very interesting for us to hear that there's an association in people with disease, but what about in our day to day life? Well, I'm of course going to disappoint you and say that there is a lot less work that has been done in the microbiome in disease in dogs. There is almost no work at all that has been done in cats, but I'll tell you what we do know, and most of it is around the gut.

So I showed you this diagram previously on the left here, so the, the healthy dogs, this heat map of healthy dogs. But similar work has been done in dogs, firstly with acute gut diseases. So you can see that there's some additional columns here on the right hand side.

These are dogs with NHD, so non-hemorrhagic diarrhoea or AHD acute hemorrhagic diarrhoea. And so essentially these are dogs with acute gastroenteritiss of some description. And certainly it doesn't take me to tell you that there are some obvious changes here.

We can see that in our acute gastroenteritis patients, there does seem to be a reduction in some of our groups of of bacteria. You can see that towards the bottom. And in some of our particularly acute hemorrhagic disease dogs, there is an increase in, in other groups of bug.

So there is a dysbiosis that is associated with acute forms of of gastroenteritis. And you can drill down into that in more detail. You can see these, you know, diagrams that that demonstrate that.

So again, we've got our, healthy dogs, which are H, and then we've got our NHD drugs and our acute hemorrhagic diarrhoea dogs. You've actually got some chronic entopathy dogs, which I'll talk about in a minute on here as well. You can see compared to your healthy dogs, if we look and drill down into some of our, our groups, that there is a significant increase, particularly in our acute hemorrhagic diarrhoea dogs, for example.

What about in chronic gut diseases? Well, again, both in that publication and in in some other work, similar work has been done, and this is another heat map, and this is the opposite now, so on the right we've got some control dogs and then predominantly on the left we've got what they call IBD dogs, so chronic inflammatory entropathy dogs, and you can kind of get the impression, particularly clustered down the bottom of that list, that there is an increase in certain groups of bug in our our chronic entropathy dogs. We'll view that in a slightly different way, so again, our control dogs are the red bars, our blue bars are the the chronic entropathy dogs.

And we can see, you know, that there is a reduction in some of our, our groups of bug. There's an increase in other groups of bug. And if you look in general, we tend to see an increase in gramme negatives and a reduction in some of our anaerobes.

Maybe that's intuitive, you know. Many of the, the more pathogenic bugs that we worry about in some of these dogs are gramme negatives. We know that anaerobess potentially can have a protective effect on the gut.

Some people think, you know, anaerobes may be the things that, that actually, you know, outcompete and stop us getting overgrowth of some of our more unpleasant gram-negative bugs. So we see a shift associated with both acute and chronic gut diseases. That's about as much as we know in terms of disease and certainly there's been no work really done looking at dysbiosis in in any of the other diseases that we may encounter regularly, but hopefully that's that's on the way.

So The obvious question, I suppose, is, should we be evaluating the microbiome in practise? You know, is it a necessary thing for us to do? Should we be looking at other things such as the measurement of metabolites?

I think for me at the moment, it probably is not that useful a thing for us to do routinely. We know that most dogs with gut disease have dysbiosis. We can probably, you know, assume that there will be a good degree of dysbiosis present from the fact that we diagnose a gut disease.

What we don't understand enough about yet, and maybe this will come in the future, there may be certain patterns of dysbiosis, for example, that, you know, encourage a response to a particular treatment. And I think when we understand more about those dogs and then, you know, evaluating those things probably becomes more useful clinically. Probably the same with some of our metabolites.

We know so little about, you know, many of the functions of some of these metabolites that actually evaluating them is probably not that useful a thing to do. Sometimes we do measure things like bile acids, as I mentioned before, when we're worried about, you know, the impact of bile acids as a potential cause of diarrhoea, but it's it's a relatively uncommon thing to do, not something that we're going to be advocating routinely. So.

I think these are very interesting things to do as part of research projects. Hopefully as our understanding evolves and we can pick out, you know, particular individuals or particular patterns of this biosis, then it can become a more useful thing to do. At the moment, it may be more for our interest.

Now if we do decide we want to evaluate the microbiome, it's worth just being aware of this thing called the dysbiosis index, cos you may see this described if you start trying to look into it for for your patients. The dysbiosis index is a method of evaluating the microbiome. That is largely used by the Texas GI Lab, who are the guys who've done much of the work on, on dysbiosis in the States.

It's now available through IEX, it's licenced to IDEX, so, you can run this as a, as a test, you can run it from the UK now as well. Essentially what was documented by that group when they were doing some of their early work into dysbiosis is that if you try and evaluate for dysbiosis in dogs, it is actually a relatively small number of bacteria that start to change. I think in in their studies it's about 8 or 9 different bacteria.

And so rather than evaluating all of the bacteria within the gut. What they demonstrated is that if you just look at, you know, that group of 8 or 9 bacteria, you can predict this biosis on that basis, and that's a cheaper and more straightforward test to run. So if you want a kind of yes no answer as to whether this biosis is present, or perhaps if you want to follow this over time in an individual patient, that is a slightly more accessible way to do that than measuring, you know, the whole microbiome, so.

Just be aware of that as a, as a kind of potentially a practical tool that you could consider using. So what's our conclusions about the microbiome in disease? Well, as I've mentioned, there is a lot of work that still needs to be done when we consider the microbiome, but there are some key changes that we seem to see in people and dogs with gut diseases.

That is a loss of diversity. It is often a reduction in our anaerobes. It's an increase in our gramme negatives, and then there's some alteration in our metabolites.

Not, not that we necessarily understand that, but it can can occur. And we can therefore infer from that that there are also things that indicate potentially a more healthy microbiome, and that includes diversity. It probably includes a predominance of anaerobess and then a good kind of balance of the metabolites that ought to be there.

So that's probably what we should kind of aspire to our microbiomes looking like, and the other things are probably things that we want to avoid. So really what that means is that the microbiome, this little world that lives within inside us, is much like the society that is around us. Actually, what we need is a diverse microbiome in the same way that we need a diverse society.

We need everybody doing different things and contributing in different ways, you know, we need our builders, we need our Amazon delivery drivers, we need our farmers, we need our teachers, we need our business people, etc. And if we get all of those people in the right balance, then society functions as a, you know, a a useful society and our children are educated and and everything kind of works effectively. What we don't want is an overgrowth of our gramme negatives, our Putin's, our Trump's, you know, these kind of people, because they have a negative impact on our society in the same way that those gramme negatives could have a negative impact on our gut.

So what we want is a nice, healthy, diverse environment inside our gut in the same way we want a nice, healthy, diverse society around us. So what are my key points for us to take home about the microbiome before we kind of move on to looking at how we can manipulate this? It is that microbiome alterations are seen in both acute and chronic gut diseases, likely in other disease states, and there's lots of work for us to do to explore that.

We know that the microbiome has lots of functions and therefore there are logical reasons why this biosis can contribute to disease. And therefore, it is logical that manipulation of the microbiome could be a useful thing for us to do in the diseases that we encounter, certainly in gut diseases, but potentially in some of our other diseases as well. So let's come on therefore to talk about that manipulation.

We have lots of ways to do that. Some of those are going to be things that are more familiar with you than others. So, of course, antibiotics has an impact on our microbiome.

Diet, prebiotics has an impact. Probiotics have an impact. And things like faecal matter transplantation have an impact.

And actually, perhaps I should also include, you know, other things that have been demonstrated to have an impact on the microbiome. So other drugs that we reach for, for example, can have an impact. Look at, I don't know, drugs such as omeprazole, you know, we dish out omeprazole left, right and centre, and we used to consider that a fairly benign drug to use.

But actually, the presence of acid in your upper gastrointestinal tract has an important regulatory effect on the bacteria, so particularly in the upper part of your gastrointestinal tract. So if you give drugs to impact that, you have a knock-on effect on your microbiome, and that could potentially be, you know, a negative thing to see. So there are other things that also have an effect, but perhaps not so deliberate, but things that we should be aware of nonetheless, you know, when we we intervene in the way that we do, we need to be aware of the knock-on effect that that may have on the microbiome.

So let's look at those things in turn. Antibiotics. We know that antibiotics were a kind of conventional drug for us to use in gastrointestinal diseases.

If I go back, you know, 5 years, certainly 10 years. An antibiotic trial was considered a standard intervention when it comes to, to kind of chronic gut diseases in our patients. And actually I look back now on that time and the amount of antibiotics I probably used in that setting and kind of feel like it probably wasn't the right thing to do.

Because of course, we have increasing concern about our responsibilities to antibiotic stewardship. You know, it's a whole another lecture to talk about, you know, the issues associated with resistance and the impact that has on our patients and as a global health crisis. But we need to be aware of those things and we need to be responsible in the way that we use antibiotics.

On top of that, we are becoming aware of the potential for antibiotics to cause harm, and that harm is not necessarily something that we can measure immediately, it may be something that occurs further down the road. But antibiotics are not benign drugs to use. There's some great work looking at the impact of antibiotics on the microbiome.

So this is a group of dogs who were given metronidazole, and this is using this thing called the dysbiosis index that we were talking about before. Now in normal dogs, your dysbiosis index should be negative. So you know normal dogs have a negative dysbiosis index.

If your dysbiosis index is positive, that is a marker that you have dysbiosis. So if you take normal dogs and you follow them for a period of time, most of them sit in the negative. If you give them metronidazole for a couple of weeks, you induce a dysbiosis.

The metronidazole relatively quickly causes dysbiosis. But then concerningly, when you discontinue metronidazole, it takes a long time for that dysbiosis to resolve. So if you give a couple of weeks of antibiotics, say metronidazole, actually, even a month after you have finished giving those, many of the dogs still have a dysbiosis in comparison to where they were before.

And actually, if you follow those dogs through, it can take many dogs weeks and weeks, months and months before their gut recovers from those things. So actually from a microbiome point of view, these drugs that we commonly used in our patients seem to induce dysbiosis, and that may be an unhelpful thing for us to do in gut diseases. And at the same time, of course, we have to have a little look at the evidence to say, are antibiotics actually a useful thing for us to use in gut disease.

And whilst of course all of us have anecdotal cases that seem to respond to antibiotics, if you look overall at the literature, there's very little evidence to say that antibiotics are useful. If we look at acute gastroenteropathies, even hemorrhagic gastroenterroopathies, it has been documented that there is no benefit to antibiotics over no antibiotics, even in dogs who show some criteria of sepsis, which we used to think was an immediate red flag that we should give antibiotics. And Same with chronic entroopathies, if we look at whether the metronidazole is useful as an addition to, say, steroids, for example, in the management of chronic entropathy, there was no benefit documented in these studies.

So, they don't seem to be a particularly useful thing. People always raise the suggestion that metronidazole has some kind of anti-inflammatory effect. Actually, if you try and look back in the literature as to where that comes from, the, the, the, the interpretation of the evidence, I think is really very generous, and they come from studies, in guinea pigs, kind of many, many decades.

And and actually I think the conclusions are probably not sound. So I think we have very little evidence that says that that antibiotics such as metronidazole have an anti-inflammatory effect. So, you know, for me, we have very little evidence to say that antibiotics are a particularly useful thing for us to use in this setting.

So what about the risk of harm, I mentioned this before. This is human evidence looking at whether exposure to antibiotics has an impact on your risk of disease. And actually it's a little bit scary and particularly a lot of the work is done with children.

As a child, if you have antibiotics, it increases your risk of various things. So when you're a very young age, if you have antibiotics, it can increase your risk of childhood obesity, it can increase your risk of infections, asthma, allergies, type one diabetes, . Potentially encourages the development of resistant organisms within your gut.

A little bit later in life, can increase your risk of type 2 diabetes. And throughout life, exposure to antibiotics, then there's a major risk factor for things like C. Difficile in in people.

So it's quite scary in a way this, that, that these are obviously risks that are not directly attributed to the antibiotic at the time that you give it. You may not be able to document these things immediately. But perhaps these are issues that we see further down the road.

And is that, and this is, you know, a question, not something I have any evidence on, but you know, we see a lot more immune-mediated diseases in cats and dogs than we ever did before. Is that because we're using a lot more antibiotics than we did before and that's having an impact on their microbiome and favouring these kind of environments. It's a question that would be great to, you know, follow groups of dogs through and try and answer, but of course the work has not yet been done.

But the take home message is antibiotics are not a completely benign drug. We can't say that they definitely won't do harm. We can't measure that harm very easily, but there has been an association shown.

So I think overall for me it does, you know, raise this question are antibiotics a useful way to manipulate the microbiome? Is there still a role for them in gastrointestinal disease? And I'll be honest, my answer to this is no, I don't routinely use antibiotics in chronic gastrointestinal diseases or acute gastrointestinal diseases.

I look for every other alternative first and only really use them in situations where they're specifically indicated, such as ulcerative colitis in the boxes, which we know is associated with an E. Coli, and we do not as a blanket effect now use antibiotic trials in chronic entroopathy patients anymore. That's really fallen out of favour.

Moving on to diet, so diet is one of those long-standing things, isn't it? We, we know from our own experiences that particular diets can have an impact on what comes out the other end. We could see if we gave more fibre, it could give us a clinical benefit, so changes in stool quality, potentially increases in some of the beneficial bacteria or increases in short chain fatty acids.

But a lot of the work that was done looking at diet is quite old, you know, using our old methods of culture or before we had access to advanced methods looking at our metabolites. However, there's been some more useful work done more recently, a lot of that done by some of the companies who are starting to launch things that intervene in this area, such as hills, who you may have seen have launched these range now of diets that have this biome claim behind it, this active biomech technology. So there's been some work looking at now sequencing and looking at some metabolites, these postbiotics, showing that actually, you know, particular packages of fibre can have, you know, particularly beneficial effects.

So, you know, looking at the individual bugs that they may encourage, looking at some of these postbiotics, the metabolites that that favour, you know, antioxidant or anti-inflammatory type of effects. And so, you know, we know that using those kind of fibre technologies can have more specific or more measurable benefits. And I think this is a really interesting area now that probably is going to become more kind of prevalent across our different, particularly prescription diets over the next few years in terms of the different claims that come out of, of different pet food manufacturers.

But certainly fibre is a, you know, a really important thing in terms of, of diet. And particular types of fibre may be more beneficial than others, and I think that's a bit of a kind of watch, you know, watch this space thing. The original diet, this gastrointestinal biome diet, was this kind of higher fibre diet that was launched now a few years ago, but this kind of active biomech technology is now finding its way into some of Hill's other diets, and I think that's a really interesting area to explore.

But certainly when we look at dogs with gut disease, these are the kind of things that we might start to play around with in terms of some of these, these manipulations. OK, so probiotics is another enormous topic and and potentially is another lecture in its own right, but we'll try and do it justice as much as possible. We know that there are huge numbers of probiotic products that are available to us, both veterinary and human probiotics, and that this is a largely unregulated area.

So we know that because these are regarded as nutritional supplements rather than drugs, that they're not an area that have to necessarily demonstrate efficacy. We know that if you look at most of the veterinary products, they pretty much contain the same thing. They all tend to contain an enterococcus vacuum, probiotic, but they can differ in the prebiotics and the fibre aspect of that, and they can differ in the amount.

And there are a few probiotics that are appearing now that contain different things, but most of the kind of commonly used ones will contain the same thing. Now how can probiotics be a useful thing to to to do? Well, there's lots of things that are hypothesised in that area, so could they displace pathogens in the gut?

Could the metabolites of some of these be particular antimicrobial substances? Could they favour immune responses? You know, all these other metabolites having other functions?

The challenge is that for most of the probiotics that we use, if not all, we don't actually know the function of the bacteria that we're giving. We don't know what the metabolites that those bacteria produce are. And that makes it quite difficult to, you know, give.

Definite advice over which probiotics might be useful things to use because we don't actually know their function. It is an area also where one has to be a little bit cautious about safety. This was some nice work that was done by Scott Weies a few years ago, looking at the commercially available probiotics at the time and what they actually contained.

And actually relatively few products, contained, you know, what, what they said on the label. And some of the products actually contained pathogenic bacteria. And so I think we have to be a little bit careful as well with this largely unregulated industry, that, that we may be selecting products that could do harm.

There's no evidence that they have, but they do contain organisms where that would have to be a potential. The take home message from his study was that the companies that are large companies with good quality control tended to have products that were more likely to contain what they say on the tin. Maybe that's, I guess, intuitive that these large companies will have better quality control measures and therefore, you know, we're going to get better, better outcomes from those.

Now, as I said before, the same is true in human probiotics. If you walk into a health food shop, you will see a bewildering array of probiotics on the shelf, and these are often things that make, you know, quite bold claims as to the the health benefits that they will infer on us. And again, often it is not particularly backed up by evidence.

But there is some evidence in people, so there are some areas where probiotics have been demonstrated to be effective. So we know that in certain forms of diarrhoea, so for example, infectious diarrhoea, probiotics can be useful. We know that they've shown some benefit in certain situations with antibiotic associated diarrhoea and prevention of of rotavirus diarrheas.

There's been some work done looking at diseases that are similar to some of the diseases we're gonna see are chronic endroopathy patients, so certain forms of inflammatory bowel disease, so pouitis or ulcerative colitis, and I think that's a, you know, an interesting area to consider. There's been some work looking at enhanced immune responses or enhanced response to vaccination with certain forms of probiotic. And with certain forms of atopic eczema, for example.

But what has been shown in people is that the response can often be very strain specific. So for example, if you take a particular strain of Lactobacillus, so Lactobacillus GG that was demonstrated to reduce the transmission and reduce the clinical signs associated with rotavirus. If you take other strains of Lactobacillus, so for example, Lactobacillus acidophilus, it did nothing at all.

And so, you know, when we kind of look at the evidence for this, I think we need to look carefully at what the strains are that are being used because we may not find that the the response is the same across different strains. What about in our patients? So has any work been done to look at probiotics in these groups?

So, when it comes to acute diarrheas, there's been work looking at the comparing, in this group, metronizole, probiotic or a placebo in the management of acute diarrheas. And there was no difference between these different groups. So it didn't seem that the probiotic did any more than a placebo.

We've already discussed the fact that we don't think there's any evidence that suggests that metronidazole is particularly useful. So no real evidence to say that probiotics are helpful in acute disease in this setting. Other acute diseases, so there's been, this evaluation looking at the role of probiotic prebiotic supplements on diarrhoea in dogs that were going into shelters.

There was a reduced incidence of diarrhoea in that setting. So there's some suggestion that perhaps that probiotic was helpful in dogs when they were going into a stressful environment. Although this was a probiotic that also contains a prebiotic, so a fibre supplement.

And so of course we don't really know whether it was the fibre or whether it was the probiotic that was useful in that setting. Another area that I think is very interesting, looking at probiotic in dogs with parvovirus, and this did show a benefit, at least at face value, of using probiotics. This was a probiotic called VSL number 3.

There was a 90% survival in the dogs who were treated with a probiotic versus 70% in the untreated group. So maybe there's a benefit in in parvovirus, at least with that particular probiotic. What about in chronic disease?

It's a nice little study again involving the Texas GI Group a few years ago, looking at comparing various features in dogs who were either treated with what they called standard therapy, which was a combination of prednisolone and metronidazole, or treated with this probiotic called VSL number 3. And actually what they found is that clinically, these groups did the same. So dogs who were given that probiotic ultimately did the same clinically as dogs who were given what is I guess a more aggressive therapy.

It did take the probiotic group a little bit longer to improve than the steroid antibiotic group, but ultimately they did the same clinically, and they started trying to look at whether there were other kinds of benefits. So, you know, they did demonstrate that there was a resolution of the dysbiosis, for example, in the probiotic group. So there's a little bit of evidence there to say that probiotics may be helpful in chronic gastrointestinal disease.

I mentioned before that that probiotics with antibiotics, you know, there has been some evidence in people to say that that's useful. There is also some conflicting evidence here, and actually in in one of these human studies, this particular one, using probiotics actually reduced the recovery or delayed the recovery from the dysbiosis induced by by anti. So, you know, there's conflicting evidence when it comes to this.

Actually, the best route in, you know, management of of antibiotics associated diarrhoea was to do a self faecal transplant. So to take some stool from before you had antibiotics and reinoculate that back into your body, that resulted in the most rapid resolution of the dysbiosis associated with antibiotic use. So, you know, as I say, it's a little bit conflicting evidence when it comes to antibiotics.

What about in other diseases? Well, you know, there has been a little bit of work done on probiotics in kidney diseases. This was some quite nice work showing that glomerular filtration rate did increase in dogs who were given this probiotic, again, this thing called VSL number 3, which is, is, you know, some, some quite interesting preliminary data to say maybe these are things that we ought to be using in, in some of our patients who have, you know, for example, chronic kidney diseases.

So you'll have heard me mention a few times VSL number 3, and actually, if you look at the evidence looking at probiotics, many of the studies that show a positive benefit use this exact product, this thing called VSL number 3. How does that compare to some of the things that we have or that are, that are, you know, kind of widely given to us as. As veterinary probiotics, well, it is a different type of of probiotic in terms of the fact it is very high potency, contains a lot of bacteria, 450 billion bacteria per sachet, which is a lot more than we see in most of the veterinary preparations, and it's also a multi-strain probiotic.

It contains eight different strains of bacteria. And so based on the evidence we have, maybe using high potency, multi-strain bacterial products, these kind of probiotics, is more useful than using low potency single strain. And to a degree that may be intuitive, we're trying to use a manipulation on what is a very complex area, you know, using something that actually gives lots of different bacteria may be more useful.

Just to confuse you, if you are interested in using VSL number 3, actually that particular formulation that has been used in these studies is now sold in different names in different places. So if you're in the UK or Europe, that is now sold as a product called Vivo Mix. If you're in the US, it's marketed under the name of Visyome, and there is actually a veterinary version of Visyome.

And so those are the products that you want to look for if you're keen to use these things. You can still buy a product called VSL Number 3, but it doesn't actually contain exactly the same as what was in the previous product, VSL Number 3. They sold the licence for that product later on.

So Viva Mix is probably the probiotics to use. And I think for me, if I do use probiotics, I tend to try and use one of those if I'm going to. So what can we conclude about probiotics?

Well, certainly further work is needed, but products containing multiple strains may be better. We should be careful with our choice of products and that there is potentially some, some, some aspect of harm. There was some early human work suggesting that probiotics could actually worsen the outcome in things like acute pancreatitis, although that hasn't been backed up by by later work.

So, you know, it's probably something we don't need to worry about too much. Lastly then, let's talk about faecal transplantation, which has had a huge resurgence over the last few years, particularly as a treatment in in people for C. Difficile.

This has origins many, many years ago in China, people used to consume this thing called yellow soup, which was a bit of a cure-all, and perhaps now we're going to find out why. How do we do faecal transplantation? We tend to take fresh stool, that we take from ideally screened donors.

We whiz that up in a blender, so we put that with some saline. Usually we do that in about a 1 to 4 ratio. As I say, we whiz that up in our blender and you don't want to do this in your own blender, you know, borrow someone else's blender for this because you're not gonna want to use it for your smoothies afterwards.

We sieve it to remove any particulate matter. And then we tend to give this by retention enema. And that's because actually if you look at the evidence in people, the route of administration doesn't seem to make too much of a difference, and retention enema is a much easier way to do this than trying to give it, you know, endoscopically into the small intestine, for example.

And so that's, that's how we tend to do this and and how we're doing this in the studies that we're doing at the moment looking into to faecal transplantation, but you could give it in other ways. If you give it orally, we tend to give antacids potentially to try and reduce the, you know, degradation of this within an acidic stomach environment. We try and, avoid antibiotics at least for a few days before doing this, because obviously they could have some negative effect from that point of view.

So what evidence do we have that this may be a useful thing to use? Well, increasing evidence in people, as I mentioned before, C. Difficile, which is very challenging to treat enteric infection in humans, has a very high response rate to faecal transplantation over 95%, which is well over what is achieved with antibiotics, for example.

Some work done to look at inflammatory entropathy, so the kind of conditions that may be similar to the things that we want to treat in our patients. So around 30% of Crohn's disease patients, around 25% of ulcerative colitis patients can see a positive response to FMT. There is some potential for harm in terms of the fact that there has been worsening of diarrhoea seen in in some patients, and there's lots of work done for for other conditions.

Now just to flag in people, there has been one death that was thought to be associated with faecal transplantation that occurred in the States and did result in massive delays to many of the studies that were going on looking into faecal transplantation for obvious reasons. Actually, when that was kind of drilled down, it was really a failure of screening. This was a heavily immunosuppressed person who had a faecal transplantation as part of a study.

Probably they were never a great candidate perhaps for that. And they picked up a nasty enteric infection that ultimately resulted in their death. They hadn't identified that organism on their screening of that stool.

They did then identify it when they re-screened the stool later on. So it was really a failure of their screening processes more than anything else. And I don't think we really need to worry about that too much in our patients because we don't really see enteric infections that commonly.

So, as I say, probably not something we need to worry about too much. What about in our patients? Well, there is some evidence that's now starting to come to light.

So, Scott Wee has done a series of case reports, demonstrating some positive effects of faecal transplantation. And there is again some work done on parvovirus puppies with, with faecal transplantation to show a faster resolution of diarrhoea, shorter periods of hospitalisation in parvovirus dogs that receive a faecal transplant. So obviously, you know, telling us that that in parvovirus, this dysbiosis that ensues as a result of that infection is a significant part of the disease.

What about in chronic entropathy? Well, there's been a kind of questionnaire type study that was published, you know, relatively recently by Silka from Edinburgh, and anecdotally people were responding. We're reporting around a 50% response rate, again with some adverse effects reported, including increased severity of diarrhoea.

There is lots of work ongoing. We have a big clinical trial ongoing at the moment looking at the role of faecal transplantation in chronic entroopathy involving multiple referral centres across the UK. So, you know, there is, there is hopefully more evidence to come when it comes to, to faecal transplantation.

There is also some work that has been done looking at the impact of faecal transplantation on the microbiome, again, using this dysbiosis index, it shows that dogs who have dysbiosis can have that dysbiosis normalised with faecal transplantation. In some cases that normalisation persists. In some cases it seems.

Rebound afterwards, and I think that mirrors what we see in our patients when we treat them for dysbiosis with this manner. Some animals seem to respond completely and some some animals seem to get a partial response that is only temporary, and we need to understand more about the, you know, the role of this in different situations. So what can we say overall about faecal transplantation?

There has been some promising early experience, but I think there is more work that is needed before we can really routinely advise this in in our patients. So what are our key take-home messages when it comes to the microbiome? Well, alterations in the microbiome are seen in lots of the diseases that we encounter, and we spoke about why there are logical reasons that that could be involved in the pathogenesis of those diseases.

There are various options that exist that may manipulate the microbiome and they may be useful things for us to use alongside our other treatments. Ultimately, we need a lot more work to work out, you know, which patients are going to benefit from this and to, you know, to pick those out from a line up so that we know what the response is going to be in, in these different groups. And that work thankfully is, is ongoing in many places.

How can we practically use this at the moment? Well, I tend to think about trying to manipulate the microbiome in patients where I think this biosis is a really significant factor. So in our younger dogs, in dogs who've had lots of antibiotics, where there's been a poor response to conventional therapies.

Well, really in dogs with relatively low clinical severities, you know, where we want to try and avoid giving immunosuppressant steroids, for example, but maybe dogs who don't have significant protein using andthropathies, for example, those are the dogs where, you know, you're looking at trying to manipulate the microbiome would be much more benign interventions than giving them some of these other treatments. And perhaps we should be combining these, these products, these manipulations to maximise the response. So, you know, if we can get an improvement with faecal transplantation, can we then improve that and and maintain that by looking at diet or probiotics, for example?

And I think this is all stuff for us to uncover over time. So, This is stuff to play around with. These give us additional trials that we can reach for in our patients, as I say, things that are not steroids, they're not, you know, other nasty immunosuppressants, but are other things that we can kind of work our way through.

And if we have to kind of put this into our algorithms of treatment, you know, for low clinical severity dogs. I think probiotic supplementation, playing around with more with our diets, looking at the manipulation in terms of fibre, potentially looking at faecal transplantation are all great things that we could consider, you know, before we get to the point where we're going to use steroids, and certainly antibiotics now come way down that list and are preferably avoided. Thank you very much for your time.

I hope that you've enjoyed this whistle stop tour around the microbiome. I hope if we talk about this again in a year or two's time that we have more evidence and more, more, you know, solid material to be able to share with you. Until then, if you have questions about how the microbiome can be manipulated in your patients, do get in touch with me.

My email was, was at the start of this presentation. I'm happy to answer any questions by by email. Otherwise, thank you very much for your time, and enjoy the rest of your day.