So, without further ado, I'm delighted to be able to welcome Professor Alex German. He's an internal medicine specialist. He's been at the University of Liverpool for the past 21 years, and he's had the weight management clinic for 18 years there.
So, we're really happy to have Alex on board today, and he's going to be talking about tackling comorbidities in dogs and cats with obesity. Hi, everyone, it's great to be here. Just give a few seconds, hopefully I can.
Just to sort out sharing was the biggest problem. Let's just see if I can get the right one. Great, so hopefully you can see the slides.
And yes, we, so welcome to the Ware. It's always good to start and to be able to kick off. And in this first session, what I want to be able to do is talk to you about how we manage patients, that have both obesity and some other problem as well.
And as I hope to be able to highlight, this actually is more common than perhaps we, we, we, we've always thought. And therefore, actually, most of our patients arguably might fit into this sort of bracket. So I hope that the, hints and the tips I'm gonna give you through the course of this presentation, will give you some food for thought, for use in your own patients.
So, it's early in the day, let's, let's start at a kind of easy level. Hopefully, everybody. Knows what one of these is.
So this is a clinical nutrition textbook. There are many different varieties available. This is just one of many.
And I suspect the chances are that many, if not most of you will have one of these sorts of textbooks or a similar one present in your practise or on your shelf at home. Now, if you've ever looked inside the book, and many people don't, of course, I'm guilty of that, when it comes to textbooks myself. But if you do look inside, what you'll find within the chapters of such a book is one of these.
This is an obesity chapter, and that will give you a lot of detail about what obesity is in cats and dogs. We'll talk about causes of obesity, consequences that can develop, and of course, also a lot about how it can be managed, particularly in terms of using therapeutic diets and so on and so forth. So that's great.
The problem when it comes to textbooks, and this is a a problem in general, is it tends to view diseases in isolation. So the obesity chapter essentially deals with obesity, managing a patient with obesity as if that's the only thing that's going on. That's what I would call kind of one size weight loss.
OK, you've just got obesity, here's the plan, and off you go. But as I hope most of you will know if you've had experience with managing, cases with obesity, one size clearly doesn't fit all. As an example, here are 7 different patients, and you'll be seeing more about these patients as we go through the talk, that essentially present a much wider spectrum of what we can see in our cases.
So firstly, we've got 2 cats and 5 dogs, so there may be some species differences that we have to consider when we're thinking about a weight plan. Of course, particularly in dogs, there's a a range of breed as well, and that might have an influence. But note also, these patients differ in their age, from very young, Sky at the top, to, you know, too old, so we've got patients here that are 10 years and sometimes even older.
Added to that, they can be male or female, they can be neutered, they may not be. And if you look at the little figures at the bottom of each photograph, you'll see they vary in how overweight they have. You heard in my bio, we, we, we run a specialist weight management clinic at the University of Liverpool.
I'll come back to this later on in this talk and the next, but we have a tool called DEXA standing for dual Energy X-ray Absorption geometry, and that enables us to quantify body. Fat mass, and that's where those numbers come from. But I just want to highlight the fact that not all patients have the same amount of obesity.
So Sullivan here is 20% above his ideal weight, whereas Tess here on the left is 100% above ideal weight. So straight away we know one size doesn't fit all. Now of course, this is a talk about comorbidities, and if we then kind of bring some of these on, we'll see that each and every one of these patients has a different comorbidity.
So Tess has hypothyroidism. Tigger has diabetes, rap here has a respiratory disease. Guinevere has mast cell tumours and is a bulldog, so of course has brachycephalic airway disease.
George has orthopaedic disease, and Sullivan, being an elderly cat, has pretty much every single disease you can think of, because as we know, cats, as they get older, tend to inherit and accumulate chronic disease. In fact, Sky is the only of our patients that had no disease whatsoever, which perhaps isn't surprising because Sky was only just over 18 months of age. .
So what I want to really now talk about is, is kind of how do we manage such patients in, in the face of having. All of, all of these different diseases going on at the same time. Just to pause for a little bit, you might say, well, this is, maybe it's being a little bit unfair.
Have I, have I sort of plucked these diseases out of the, the, you know, thin air? Are these common things, are they not? How do we actually need really to worry about other conditions when it comes to obesity?
Well, we've been running our weight clinic at Liverpool now for about 18 years. And if we look at our patients and we look at how common other diseases are, all our patients, of course, have obesity. But we find certainly somewhere in the region of 3 quarters, if not more, have at least one other disease, that, is going on at the same time.
And this table here just gives you a rough idea about the sorts of categories of disease we can see. But I want to make the point that we do see some cases, as, as with Sullivan, where there is more than one thing going on. So I would actually argue that having obesity and something else to handle is the norm rather than than the exception.
OK. So let's just now get into how do we start solving this issue? How do we start working out what do we do er where we have more than one thing going on?
Well, this is actually an aspect of a wider concept I want to introduce to you now, which is the concept of tailoring your weight plan. I've kind of talked about this in other talks, where it can, where we're looking at, setting targets and different targets based on how overweight patients are, or other criteria. But tailoring, i.e.
Adapting the plan to fit the circumstance, is particularly pertinent when it comes to, these sorts of condi cases where we've got a comorbidity, going on. OK. So the concept of tailoring means we need to look at what are the key benefits we're gonna get when we start a weight plan.
When do they occur, and I guess what, therefore would our priorities be in terms of promoting the health of an individual. So if we want to think about what benefits weight loss brings, we need to know about what the problems, with obesity are. So for example, we know from studies that obesity tends to lead to a shorter lifespan on average, particularly in dogs, a little bit in cats, as we'll deal with a little bit more er in the next talk.
Added to that, we know, and it's the subject of this particular talk, that obesity goes hand in hand with various comorbidities, and we're gonna talk through a number of those. What else can obesity do? Well, even if there's no disease, obesity can affect body function.
So there are various bodily bodily functions that are impaired when a dog or cat has obesity. That can be musculoskeletal function and mobility. It can be cardiorespiratory function, particularly function of heart and lungs, and or it can be metabolic function, things like insulin resistance developed with obesity.
So all of these are impairments of body function, even though there may be no disease. And then I guess the collection of all of these things, lifespan effects, comorbidities and function impairment means that quality of life, particularly health related quality of life is affected. OK, so that's the bad news when it comes to obesity, OK.
If we think about tailoring. Then what benefits might weight loss bring? Well, if dogs and cats tend to live a shorter lifespan on average, it may well be that weight loss can mean they live longer, perhaps.
If obesity leads to the development of other diseases, if we can get in soon enough, maybe we can prevent disease. Of course, if a comorbidity has already developed, we're not going to prevent it, but it might well be that by with through through weight loss, we might lessen the impact of that disease, to make it less severe in terms of signs than it is. Of course, if body functions are affected, like cardio respiratory function, metabolism, weight loss might improve those functions leading to the patient feeling better.
And again, the sum total hopefully will be improved quality of life. OK. The evidence for any or all of these things is somewhat variable.
OK, and there's actually more evidence for improvements of the last 3 perhaps in the 1st 2, but that's not to say for some patients, those 1st 2 aren't important. OK, so in terms of tailoring, we may tailor our plan to prioritise one or more of these weight loss benefits. OK, and let's look at that right now.
So if we view weight loss in a patient with obesity as going down the side of a mountain, OK, one goal, and this is the traditional goal, it's what will be present in all textbooks, is what we call complete weight loss. Here, we set our target weight as the ideal weight of the patient. So we work out how overweight that patient is.
Remember that Border Collie test was 100% above its ideal weight. So we estimate what its ideal weight would be, and that would be the target for the end of weight loss. However, that's not always critical, and actually for many years I've argued that lots of patients might benefit from what I call partial weight loss.
Here, although we know to be an ideal weight, they have to lose, say 100% of their weight as with tests, we might actually set the target somewhere above that. So we're only getting to lose a little bit of weight. OK.
Now if we think back to those possible weight loss benefits, these two different strategies are there to prioritise different benefits. So for complete weight loss, we would use this if we were aiming for the patient to live longer and avoid disease. Why is that?
Well, we know that dogs and cats in ideal weight tend to live longer and tend to be less likely to develop other diseases. So if we can return a dog or cat to its ideal weight, hopefully soon enough, we may be able to promote both of those. In contrast, the priority for partial weight loss are some of those other benefits, improving organ function, improving quality of life, and lessening the impact of a disease that's already happened.
So here, there's evidence suggests that we don't need complete weight loss in order to see some improvements here. And I figure I'm gonna come back to you later, but I want you to keep in mind when we're thinking about how much weight is the sort of minimum a patient has to lose to start feeling better. It's actually somewhere in the region of 6 to 9%.
I'll give you the evidence for that later on, OK. But the good news with partial weight loss is we can actually start to see some of these things changing quite quickly in our plan. We don't need to wait for them to get to ideal weight to see a benefit.
OK, so I've kind of separated a complete weight loss plan now from a partial weight loss plan and of course our priorities in terms of health improvements are different. Which patients then would benefit from complete weight loss? And which benefit patients might benefit from partial weight loss.
Well, Complete weight loss patient will likely benefit individuals that are young. And individuals that are currently healthy. And if you remember our seven cases that I introduced to you earlier, the key one here that fits the bill would be Sky, 19 month old corgi, no other diseases.
OK. So here I could make a strong case to say this dog's got a lot of life still to live and it doesn't yet have other diseases. If I can return this dog to its ideal weight and keep it there.
I'm gonna stand the best chance of it living a longer, healthier life. OK. So certainly for Sky, I think hopefully, you'd understand a complete weight loss plan is sensible.
What about partial weight loss? Well, this is more useful for individuals that are already older. Why is that?
Well, if they, if they're kind of middle aged or older, they've got less life still to live, so any benefits in lifespan are gonna be minimal. Also those that already have comorbidities and functional impairments. If they've got another disease already, we're not going to prevent it, but perhaps we can make them feel better.
So that's essentially, where we're, we're going to be aiming, to, to go. And a lot of these, you'll see, further examples will be these partial weight loss plans where it's a question of deciding how much weight do we need to lose and how do we get that. OK.
So for the rest of the talk, I want to now talk about diseases, comorbidities, diseases associated with obesity. I'm gonna talk you through the strategies we use when we come to, to looking at managing them. Now there are various studies that have been published in dogs and cats that have looked at disease associations.
Typically what they do is look at populations of dogs and cats stratified by body condition score, and they look at the prevalence of individual diseases, particularly in overweight and obese cats and dogs. And if you look at this and you sum all of them up, there are actually a load of different disorders that have been associated with obesity in either dogs or cats, or in both. So we have examples of endocrine diseases, hypothyroidism, hypergenocorticism, and diabetes.
We've got musculoskeletal disease that's present in both dogs and cats. We've got alimentary diseases like things like pancreatitis. Lipidosis and also gastrointestinal diseases things like just vomiting and diarrhoea seem to be more common in overweight dogs and cats.
And then we've got a bunch of other ones here as well. OK, so we're gonna go through not not all of these, but we're gonna go through a significant number when we look at how we manage these individual cases. Whichever of these diseases is present, the chances are it's gonna fit into one of 3 possible categories.
First category is that the comorbidity. Actually either causes the obesity or makes it worse. So having that comorbidity makes the patient more likely to develop obesity, or if they've got obesity, make that obesity worse.
That's the first option. Second option, the other way round, the obesity may have either caused the comorbidity or at least made it worse. So here we've got associations one way or the other.
And of course, the third category is where there's no causal association between the two, or at least we don't know. But these two conditions, obesity and the something else may have developed completely independently of one another. It doesn't really matter when it comes to a clinical point of view.
We still need to manage both and we need to think about how we adjust each plan to take account of the other. OK, so these are the 3 situations we're gonna talk through in term. So we'll start with this first one where the comorbidity.
Has led to the obesity or at least made it worse. In order to think about diseases that potentially can be in this category, we of course need to know what sorts of things cause obesity in the first place. So this comes back to our pathogenesis.
And again, hopefully we're on familiar territory. But what we know is that the underlying mechanism for obesity is a long term energy imbalance where energy intake exceeds energy usage over a long period of time. That positive energy balance leads to deposition of extra body fat in terms of number of cells and expansion of lipid within those.
So our adipose tissue expands over time, and that's essentially what can lead to some of those health consequences. Now, of course, there are many variables that influence the relative ease with which a patient gains or loses weight. The top two you'll notice are pertinent when it comes to comorbidities.
Either the diseases themselves may alter this energy balance, or some of the drugs we use to treat them may alter energy balance. Let me give you some examples. Let's imagine we have a dog with atopic dermatitis.
We treat it with steroids like prednisolone. A side effect of steroids, as we know is polyphagia, and if that animal is allowed to eat more, then of course that creates a positive energy balance and weight gain. So that can, that's essentially the disease indirectly through drugs causing the obesity.
Also, let's take a second example. Let's imagine a dog with orthopaedic disease like arthritis or a cruciate ligament disease. They become less active, so the energy balance is affected, and again, if food intake isn't adjusted, there's a positive energy balance overall.
Again, weight gain will be the result. The one I want to deal with in a little bit more detail is probably the one that everybody thinks about when we think about diseases that may cause obesity. And this is hypothyroidism.
And as you remember from the slide at the start, one of our cases tests this very overweight border collie, but had hypothyroidism. Now, a few points, when we're dealing with sort of hyperthyroidism both from a diagnostic and a treatment point of view, if the patient has obesity. The first thing I want to get across is that hypothyroidism is actually a very uncommon cause of obesity.
We pretty much always think about it, and many people choose to run things like T4 routinely in patients with obesity, dogs with obesity, because of the feeling that this is always going to be a cause. But actually, number one, hypothyroidism is vastly overdiagnosed in practise. I would argue we probably get it wrong as often as we get it right.
And actually, even then, relatively speaking, few cases with obesity actually have hypothyroidism. And to show you, to illustrate this, I just want to show you some simple maths. Now, if you look at textbooks and you look at prevalence data, the prevalence of hypothyroidism is somewhere under 1%, between 0.2% and 0.8%.
And in clinical signs, just under half of dogs with hypothyroidism have weight gain as a clinical sign. So if we're looking at weight gain associated with hypothyroidism, we've probably got a prevalence of somewhere under 0.5% of the dog population.
If you know anything about obesity in dogs, we know that our current prevalence of dogs that are either overweight or in obese condition is somewhere in the region of 50 to 60%. So you do the maths here, it's quite simple. The vast majority of patients that you see that are above our ideal weight will not have hypothyroidism as their number one, as their main cause.
Now this actually, these data actually, chime with what we've seen in our weight clinic. So we've seen over 400 dogs with obesity now and being a specialist clinic, we test each and every one of them for hypothyroidism, and we've only found this condition in 8, which is about 2% of all our patients. Remember, it's a specialist clinic, we deal with problem cases, so we're probably going to see them more often anyway.
OK. So for, for this in mind from a diagnostic point of view, I wouldn't say run T4 routinely in patients that are overweight. I would look for other signs that might indicate you need to.
So if the patient is middle aged or older, that's where hypothyroidism occurs. That might be more sensible time. If there are skin changes consistent with hypothyroidism or other signs for that matter, things like alopecia and so on, again, you might want to run that.
If you've done routine blood tests and the cholesterol is very high, that's something which is very common in hypothyroid patients, so that would be another indication. And finally, if you've started a weight plan, You're confident that you've got your calculations right and the owner is doing everything that you say, that might be a situation where you would test for thyroid disease as well, if they're not losing weight as expected. OK, so that's the first point about hypothyroidism.
It's uncommon, don't need to test for it all the time. But the other point I want to make is treating these cases, because again, we frequently get this wrong. When we make a diagnosis of hypothyroidism, or to be honest, any other disease rather than that goes alongside obesity, we always get blinkered and we only think about treating that particular disease.
So it's right that we do and should treat them with thyroid replacement therapy, levothyroxine either in tablet or liquid form. But don't forget, these patients are overweight, so you also need to put them on a weight management plan as well. And many people just elect to treat with thyroid drugs and not the weight plan.
So they respond and they lose some weight, but they don't lose enough weight really to be of major benefit because we've only done part of the job. OK. So, thyroid replacement therapy and of course use blood samples to monitor.
But always add a weight plan as well as we did in Tess's case. So, his tests before weight loss, when she had 48% body fat, as you can see. And this was her after weight loss, and you'll notice that she actually lost 37% of weight, so she did very well.
She, her body fat after weight loss was 32%, and for a border collie, we'd probably expect about 25% to be her optimal. And I think you can probably see from her shape that she's still a bit overweight. But that goes to, that, that was basically the point where we got most benefits.
And there is some good news when we treat with, these cases, because you've got the thyroid therapy on board and you're treating that disease, they typically lose weight pretty well. So if anything, although we've not got enough to, to, to give an accurate figure, I would tend to think that success is likely to be better because you, you're kind of treating a medical and the obesity condition there. OK, so that's our first category.
Let's now move on to our second category where we, the obesity has caused the comorbidity this time, or at least made that comorbidity worse. And if we go back to our list of comorbidities, there are 3 that I'm gonna talk through for you right now. So we'll talk through orthopaedic disease, we'll say something about diabetes, and we'll also talk about respiratory disease in this category.
You'll see there are some similarities with how, strategically we approach these, but there are some slight tweaks as well. OK. So if you deal with a situation where you think the obesity has either caused or made the disease worse, there are certain questions you then need to ask yourself in terms of prioritising what you do about it.
First question. Will the weight loss benefit the comorbidity? OK.
The chances are a lot of the impact on health for this patient is from the comorbidity. It's the ill other illness that's making that patient worse. So, really, to be honest, our priority for weight loss should be for patients where we think actually that weight loss is gonna make that, that, that particular disease better or at least improve it.
If you're happy, there's gonna be a benefit. Then of course a weight plan is recommended. Our next question is, well, when do we do this?
Do we do this straight away? Do we wait for a bit and maybe treat the comorbidity, or do, or, or do we kind of do a bit of both? OK, so we think we need to think about when the weight loss comes in the overall strategy of treatment.
And then a further thing would be, do we need to make any adjustments to the weight programme itself in the face of that comorbidity? Do we need to alter how we, the type of food, how we feed it, what we feed, and why? OK, so those are our main questions and I'm gonna illustrate these when we're talking about the cases that I'll show you.
So, let's start with George. As you can see, George, De Labrador, very, very overweight. You'll notice for the body condition score, 9 point system commonly, at our clinic, we use the term 9+.
This refers to patients that are kind of beyond the scale. We know with our DEXA that we, we can grade obesity well beyond that, and we have patients that are 100% and, and more above ideal weight. So you might notice 9+ appearing on those slides.
But anyway, this is a, George is a very, very overweight dog. He came to Liverpool, he was actually referred to our orthopaedic surgeons rather than to our weight clinic. And the reason for this was he had severe osteoarthritis.
OK, so these are his hips, and this is his elbow. And again, you don't really need to be an expert radiographer to see he's got severe arthritic change here. Lots of sort of osteoarthrites that misshapen, hip, joint here, you can see, and likewise, lots and lots of, lots of arthritis around, the elbow, the left elbow in particular.
And he came to Liverpool, actually, because they wanted hip and elbow replacements for him. So this is a patient where we do need to deal with both the orthopaedic disease and the obesity. So remember those questions, our first question is, can we be confident that weight loss will benefit the comorbidity?
This is a situation where I can very confidently say yes, it will. And in fact, I'm gonna be as bold as to say that weight loss in such patients is the most effective therapy for arthritis that we have. OK, I'll say that again.
Weight loss is the most effective therapy for arthritis that we have. OK. There is evidence that improvements with weight loss in terms of mobility outstrip the use of non-steroidals.
And out and certainly outstrip the use of nutraceutical drugs. We all like to use them, they have little real benefit. Whilst you can probably get better improvements in mobility through surgery, hip replacements and elbow replacements, these are obviously expensive and they're salvage procedures only for the most severe patients, and they do have complications as well.
So it's not necessary there for all. So generally overall, weight loss is best. How do I know this?
Well, there's actually a really, really good study that highlights this. One conducted by Marshall and co-workers, now over 10 years ago. What they did was they looked at patients that had both obesity and arthritis.
And they put them on actually quite a short term weight plan. And what they did was that they judged mobility before and after weight loss. Both getting owner assessments, but also force plate analysis where they were more objective in assessing mobility.
And what they found was that weight loss improved mobility, both as judged by the owners and by force plate. But the great news was that benefits were seen with a modest amount of weight loss. So 6% owners could start seeing differences and 9% when it came to to force plate analysis.
So if you remember that figure 6 to 9% I mentioned at the start in terms of priorities, it's this is the kind of minimum that we would ever aim for, but we can be confident that by doing that, we will see benefits. To illustrate this further, this is a patient that's come to our clinic, didn't actually have noticeable orthopaedic disease, although if you look at the top video, was limping very, very slightly. You'll see that on as the patient returns.
But this is before and after weight loss in the same patient, and you can see very much mobility is significantly improved with the weight loss here in terms of speed and, and kind of sprightliness overall as well. OK, so we can be very confident that weight loss in these patients will help. OK.
Second question, what about timing during weight loss? Well, ideally what we'd want to do is start our weight loss straight away if possible before any surgery, if that's, if that's feasible. Because of course, it will make anaesthetic risks, less, and it will actually provide some, some benefits and help in recovery as well and perhaps reduce complications as well.
So if we can get a little bit of weight off them before surgery, that's great. But recognise too that the surgery overall long term will lead to improvement of mobility, and that itself may help with weight loss. So it's not an either or.
There may be cases where we go for more weight loss before surgery. There may be cases where we kind of get the surgery in sooner because the mobility is so affected. Generally speaking, we kind of do a little bit and then, and then add the, the, the, the surgery in at some point along the line.
What about making adjustments to the plan? You might think that because patients with obesity and an orthopaedic disease are going to be less mobile, they won't do as well with their plan, they're less likely to succeed. And actually our evidence from our clinic suggests that's not the case.
We found that those with orthopaedic disease in terms of reaching their target, do at least as well as, as a patient that doesn't have disease. However, in order to achieve that, we found that we do need to restrict their energy intake a little more than we normally would, about 5% more or so. So if you, if you remember the numbers, typically.
We, at the start of weight loss, we begin patients on somewhere between 60 and 80 calories per kilogramme of, metabolic body weight, kilogrammes to the, to the 0.75. Here we might adjust that down by 5%.
So if it were a neutered female dog where we would normally start at 60%, we would do 55, sorry, 60 calories per per kilogramme to 0.75, we'd do 55. And that then means they do lose weight as well.
OK. Now these are in the partial weight loss camp, we know that 6 to 9% will see some improvements. So we'll start with a plan that that means they'll lose at least that amount.
That being said, we have some evidence that more weight loss improves mobility further. It does become a little bit sort of diminishing returns, but we kind of push into that first bit, but then think about going further if, if the owner is motivated. And that's what we did in George's case, so this is him before weight loss as you can see.
This is him after weight loss, so he was a partial complete. 54 kg to start, 39 at the end. Notice he's still kind of, he, he's still significantly above his ideal weight.
He's probably about 20-30% above his ideal at this point. But this, he'd lost almost 30% of his body weight despite that. And it got to the point where the owner wasn't seeing greater benefits with the weight loss and maintaining that weight loss was a challenge for him.
So that's why we, we kind of drew the plan there. He did have, hip replacements and an elbow replacement as well, that kind of helped also. That's example one.
Let's now move on to respiratory disease, and there's lots of similarity here with orthopaedic disease, but a few differences as well. OK, first things first. There are associations between obesity and respiratory disease in both dogs and cats.
For cats, there was actually some, a, a recent study which looked at associations of disease with body condition score. I'll come back to this in the second talk in a little bit more detail, but what they did was they stratified cats, in the population according to body condition score 9, so from 3 out of 9 to 9 out of 9, and they looked at their risk of having a, a series of diseases. And what we found actually was for asthma.
The risk of developing asthma was greater in overweight cats compared with cats in ideal weight. Apologies, the numbers are quite small here. But here is the odds ratio of developing asthma.
This is 5 out of 9, which is a reference group, and that's odds ratio of 1. And if you look at body condition's got 8 or 9 out of 9 at the bottom of the table, the odds ratio is about 3. So those patients, body conditions go 8 or 9 are about 3 times as likely to develop asthma, as patients in ideal weight.
So that's one that we may see as an association for cats. For dogs, probably the big one nowadays is brachycephalic airway syndrome. I'm sure we're all familiar with, these brachycephalic breeds that have kind of exploded in popularity, and many of them have this syndrome of characteristics which lead to problems breathing.
The reason for me this is a big issue is that actually these brachycephalic breeds are now the the breeds where obesity is most prevalent. These are data here from the Banfield network in North America. They have a large network of hospitals where they can look at data.
And what they found when they look at prevalence of obesity across breed, I hope you can see this little diagram here, the top breeds for a prevalence of obesity are pugs and the English bulldogs. So that for me presents a major concern. Because as we know, obesity affects breathing and respiration, and if these individuals are predisposed to brachycephalic airway syndrome, that's gonna make that worse.
And then a final condition I'm going to talk through this particular case is RAP, one of our cases who had tracheal collapse, and again, that's another one. This is a small terrier and particular breeds are predisposed to this collapsing trachea. And this is rap and and his radiograph and you can see a slightly narrowed portion of his trachea here.
OK, so. What do we do with these patients, where we have to ask those same questions. First question, will weight loss benefit the comorbidity?
Well, we have reasonable evidence that that will be the case. Firstly, we know that obesity affects, lung capacity and respiratory capacity. This is illustrated here using two human radiographs.
So a patient in weight on the left, a patient with obesity on the right, and you can see actually that the lung capacity is significantly reduced, and that's because of buildup of adipose tissue both within the chest, around the chest, and also within the neck region. OK. So potentially, weight loss and loss of this fat will lead to improved function.
We have actually demonstrated this in a small study in dogs at our clinic, where we actually looked at our dogs before weight loss. And we actually measured body fat mass using our DEXA scanner, as I mentioned before. And we also then looked at body weight, body fat mass and, after weight loss.
And what we also did was arterial blood gas analysis, so we were able to look at oxygenation and ventilation before and after weight loss. And what we found was that the respiratory function in terms of oxygenation and ventilation correlated with the amount of fat in the chest. So that's very similar to what I've shown and illustrated in those radiographs in people.
So that was the bad news. The good news is that weight loss led to improvements of both oxygenation and ventilation, and this correlated with changes in the amount of fat that was lost. Now rather than giving you the numbers, what I can show you is, some pictures of before and after weight loss, which I'll do in a moment.
So. We've got good evidence from respiratory disease that essentially weight loss is likely to benefit respiratory function and if they have patient if a patient has respiratory disease, that's gonna be a good thing. Second question, what about timing during weight loss?
Well, we've got to be a little bit careful with patients that have respiratory disease, because if they've got severe respiratory compromise, then that always has to take our priorities. So if they're, if they're cyanotic or they're collapsing, do what you need to do to stabilise those signs. That might be drug therapies, it might even be emergency surgery if needs be.
OK. If that's not the case, or once those patients are stabilised, then my recommendation is to try and get them started on a weight loss plan as soon as you can. And ideally, if you can avoid surgery beforehand, get them to lose weight before because their anaesthetic, stability will be far, far greater as will their recovery.
OK. Now, for some of the conditions we, we see, successful weight loss may mean that they don't need surgery at all. And that's, that's great news.
So it's possible that if we start with the weight loss, we get to a point where we can avoid the need for expensive and potentially risky surgery. What about adjusting the plan? Well, like with orthopaedic disease, actually you don't need to make huge numbers of adjustments to the plan.
If you've got patients with severe respiratory compromise, I would be careful about the physical activity that they do. So we're probably talking about controlled walking activity rather than lots of vigorous play activity or running and so on and so forth, particularly if they're at risk of, of syncope and collapse. OK.
Other than that, the plan can go ahead as, as planned. You might need to adjust like we do in orthopaedic disease by restricting the energy intake slightly to take into account any reduced activity. And again, like with orthopaedic ones, we probably look at a partial weight loss plan initially, but then look to push them further after that if needs be.
So this was right before weight loss, where he was 15.5 kgs, just over. After weight loss, I promise you it's the same dog.
He was under 9 kg. So he lost 41% of his body weight. He did very well and the owner was keen to pursue, to get to, to, weight loss to the end.
He didn't need any surgery for his collapsing trachea. And this was his DEXA scan before weight loss. And scan after weight loss and like with those radiographs in people, again just subjectively, you can see his lung capacity has significantly improved.
So there's good evidence that weight loss has had some benefit. OK, so let's talk about our 3rd disease where obesity can make the condition worse, and that's diabetes mellitus. One of our patients, Tigger had diabetes and his body condition scored 9 out of 9.
So let's go through that process and ask those questions. Question one, will weight loss benefit the comorbidity? Well, The evidence, particularly for cats, like in people is almost certain.
That's because cats suffer from a diabetes mellitus, which is like type 2 diabetes in people, which means that insulin resistance is the mechanism. OK, so it's the insulin being less effective. We also know that obesity leads to insulin resistance.
So if we can get successful weight loss, insulin sensitivity should improve, and therefore so shouldst stability. And I'm sure everybody's aware that some patients, if they can return to an ideal weight, might actually no longer require any insulin at all. OK.
We know weight loss improves sensitivity. We have studies that show even in patients that don't have diabetes, they have improved sensitivity. So there's clear evidence of a benefit here, particularly for cats with diabetes.
OK, let's deal with these, the, the second two questions in turn. What about timing during treatment and how should we adjust the plan? Well, I, there isn't any really good scientific evidence to tell you what you have to do.
My clinical hunch is that it's better to control the diabetes first, get that under control, get the patient stable, and then think about the weight loss afterwards. And part of the reason for that is that if these patients are metabolically unstable, making massive adjustments to what they're eating could cause problems and sort of over swinging them. So it's better we do that when we've got more control.
Added to that, I worry if they're if they're unwell they may lose more leak tissue rather than fat during weight loss. So what I would say is, start with an insulin therapy of your choice. I would typically for me, take sort of somewhere between 1 and 3 months to get them stable.
Once I'm happy they're stable, I would then think about the weight loss plan. Now, of course, we do need to think about nutrition even within this, within this setting. And typically, during this initial stage, I would go for some sort of high protein, low carbohydrate diet.
That might be one of the diabetic diets that are on the market. They typically are high protein and low in carbohydrate, and therefore improve sensitivity. Some, some individuals, if costs an issue, you might just use wet food on its own, and that has similar sorts of characteristics.
So you stabilise them then once they're stable, and assuming they're still overweight, which they likely will be, you can then switch them gradually to a therapeutic weight loss diet. And usually we would prefer a wet weight loss diet if possible, because again, it'll have the same sorts of characteristics. And then the hope then is that weight management will further improve sensitivity, and you may then be able to drop out the instant therapy all along.
OK. So that's just a little bit about sort of timings and outcomes. Again, another point, which is always a little bit of a whinge.
Often people, when they see these patients only think about the diabetes, they don't think about the weight loss. And I think we're missing a trick, particularly in terms of remission, and I think there's a good opportunity that we can, we can s we can improve patients further. OK, now let's just in the last sort of 5, 10 minutes, let's now look at the final aspect which is where we're concerned that the obesity might have caused the comorbidity, sorry.
But the obesity may or may not be related to the comorbidity and vice versa. So they, they may be two totally independent conditions or we're not particularly sure. And if we come to our list, there's gonna be two I'm gonna cover, they, they sort of similar follow a similar pattern, and this will actually bring us nicely into the topic for the second talk, after the break.
So we're gonna talk about urinary system disease, but particularly upper urinary tract, i.e., kidney disease, and we're gonna talk about cancer.
So where we're facing a disease which is unrelated or we're not sure, actually the questions we ask have to change a little bit. And the first question I always like to ask is, could I harm the patient with weight loss? So it's not about will it have some benefit initially, it's, it's will it do harm.
If the weight loss is gonna make matters worse. Forget about it, don't even go there. OK, there's no point in proceeding, OK?
If they don't, if you're not likely to harm them, then of course you do then need to ask, will it do some good? And if I'm happy, then we can contemplate a weight loss plan, and again, we then need to think about adjustments to the programme. OK.
So I guess our, our questions have shifted very slightly as you can see. So let's now deal with our penultimate case, Sullivan, who you remember was a 9 year old neutered male British short hair. He was 30% above his ideal weight, so not the most overweight patient that we've seen in the, in the bunch.
We reckon his ideal weight should be about 5.9 kg. But he had lots of other things going on, so he had arthritis, and we've talked about how we manage that.
He had borderline diabetes, so we were worried he could go full blown diabetes, particularly if he gained more weight. So we kind of had to deal with that. But in particular he had early chronic kidney disease.
So if you're familiar with the Irish staging, which is a 4 point staging, he was Irish stage 2, which is very early, and it's at a point where he, he's, he's at a stage where he's kind of stable. Whether or not he actually needs many interventions depends very much on other measurements you get. So his estimate was 21, that would put him in Irish stage two.
Importantly for Sullivan, his phosphate concentration was 1.2 millimoles per litre, so it's nicely in the normal range. Irish stats suggests a target of less than 1.5 if you're dealing with, diet therapy.
So he's kind of in an area where arguably diet may or may not be yet required. So, question. Is weight loss gonna harm this particular patient, who knows.
Now this actually just means I, I just, in order to kind of answer this, I just need to sort of just sidetrack a little bit and introduce a concept that you might have heard about called the obesity paradox. It's talked about most, most commonly for people. And the obesity paradox, I guess posits that generally speaking.
Obesity is a bad thing, so having obesity increases your risk of developing diseases and mean that you live, you, you live a shorter lifespan on average, OK. The obesity paradox happens for certain chronic diseases that lead to weight loss, such as cancer, kidney disease, heart disease. Here, actually being in overweight condition, so body mass index of 25 to 30 for a person can actually often show slightly longer survival than in ideal condition.
So this is where people talk about this paradox that maybe being a little bit overweight is a good thing if you have a chronic disease. This is a review here of the obesity paradox in cancer, and if you look in this review, you actually see one of these kind of J shaped curves. So certainly, Being in obese condition is not good, body mass index of 30 and above leads to big improvements in the hazard ratio for being dead.
But obviously being too thin is not good either, and the best point in the nadir of the curve is between 25 and 30, so that's overweight condition. OK. So that's a people on body mass index.
A similar thing has been demonstrated for cats, and there's been some great work by Lisa Freeman and colleagues at Tufts. And in this particular paper, she looked at body weight in cats with kidney disease at diagnosis and over time. And I'll come back to this study in the second talk.
But what she found was, if you looked at weight at diagnosis and risk of dying, again, it's like that last one, but this is on body weight. Again, we get this kind of U-shaped curve. So being too heavy with kidney disease shortens your lifespan.
Certainly being too thin shortens your lifespan if you have kidney disease. The optimal again is about sort of just over 6 kg. And for most domestic short haired cats, because this is in cats, again, that's likely to be an overweight condition.
OK. So some people say, well, actually that means having some extra body fat is a good thing, that fat is protecting you. What I want to emphasise is it's actually not the fat that's likely to protecting you, but lean tissue, muscle mass, OK?
Because when we look in terms of both weight. And if we back up, if we look in terms of both in body mass index in people, we're actually looking at body weight. And not how, whether that's body fat or lean.
If we actually break those two apart, this is a further study again looking at mortality risk. But here what they've done is they've they've used body composition to measure fat mass at the top and lean mass at the bottom. As your fat mass increases above the median of 21 kg, your risk of dying increases.
But interestingly, if you lose fat. You're not actually, your risk of dying doesn't increase, whereas actually if you look at the lower panel, losing lean tissue below the median means an increased risk. Yeah, OK.
So it's likely to be that this survival benefit in being in slightly overweight condition is associated with the, the lean tissue there, not the fat mass. I hope that makes sense. So, what does that mean for Sullivan?
Well, what it means is we want him to lose some weight cause that will benefit his arthritis and prevent hopefully prevent him from going into diabetes, but we don't want him to lose lean tissue. OK. We have studied body composition, as I've mentioned already, using our DEXA scanner.
So one thing we can do with our patients is we can look at weight before and after. We can look at body fat mass and and lean mass before and after weight loss in the same patient. You can see here this one had 20 kg of fat before weight loss and 12 kgs afterwards.
And we can actually work out how much fat, how much lean, and how much mineral is lost. And if you look at all of our patients, and this goes for dogs and cats, about 83% of what is lost is fat on average, and 17% is lean. However, Whilst that 70% is lean, you know, it is an average, that can be vastly different.
So some patients we've found don't lose any lean tissue at all, some gain a bit. Others can actually lose beyond 17%, sometimes even 30% or so of the weight they've lost can be lean tissue. And when we've looked at what predicts this.
What we find is that the biggest thing that predicts it is how much we get the patient to lose in terms of body weight. And this is illustrated on this scatter plot. So here, as we have patients losing more weight, these individuals here have lost somewhere between 35 and 45% of their body weight.
They always lose lean tissue. So on the Y axis we've got lean tissue change. The dotted is zero, so anything above is gaining, anything below is losing.
And if you look at this point here where individuals have lost lots of weight, they lose fat, but they can always lose lean tissue. Whereas if they're losing somewhere in the region of sort of 10 to 15% as a max. Yeah.
Then, sometimes they gain, sometimes they lose, but it's pretty neutral. So with, Sullivan, I'm gonna come back to Sullivan in the next talk. What I would aim to do is to put him on a weight loss plan, but only get him to lose 10 to 15%.
OK, I'll, I'll tell you how he did in the next talk. And then finally, similar thing would be true for Guinevere, our last case. So this was a dog, if you remember, that had brachycephalic airway disease, but also had a grade 2 mast cell tumour.
So this is, this is quite a significant cancer, and it's this that is likely to shorten this dog's lifespan, so that we're talking about weeks to months rather than months to years. So again, we have to ask those questions. Is it going to be a benefit or not to lose weight?
If this were any other breed than a bulldog, I'd probably say no. But because of this dog's affected by its brachycephalic airway disease, you know, somewhere maybe in the region of 6 to 9% weight loss could provide some benefit. OK.
So our priority in Guinevere's case obviously would be chemotherapy for the mast cell tumour. And a partial weight loss plan where we're looking at kind of alleviating those signs of disease and whilst preserving lean tissue as we, as we go along. So 6 to 9% would be the sort of target for her.
OK, so I hope that's been helpful, because there's, there's a lot of concepts in there, but I hope with those logical concepts, it can, it, it kind of makes it nice and clear as to what and why we do what we do. So let's just close by reminding you what we've talked about. Remember, concurrent disease, comorbidity is very common in cats and dogs with obesity.
We find it's present in almost all of our patients, where almost all of our patients have another disease, as well as the obesity. We know that weight loss can improve various, characteristics that can, it can maybe improve lifespan, it can prevent disease, but more often than not, when we're looking at individuals with comorbidity, we're looking at improvements in function and quality of life. And of course, we have to adopt this tailoring approach to determine, firstly, is it worth going for weight loss?
If so, if so, when and how much do we want, those individuals to lose. And I hope I've given, used those examples nicely to show that. So, thank you very much.
Thanks very much, Alex. That's really, that's really interesting as always. I've just taken over from Hannah for just a moment.
We've got some polls coming up if everybody could take part in those. They've just popped up, I better not, score. I don't think you're allowed to, Alex, but I'm sending good vibes I just got it.
Yeah, it doesn't let you do it, does it? We are gonna be asking questions, I think at the end, because we've had a few in, and we don't want to miss them. So we thought maybe we'll do them at the panel, there's one that's quite a quick, a quick question, I, I think, to take it to, yeah, to, to 10 to, to take us through to 10:35 for our break.
Why do you need to, extra restrict the 5% food intake in orthopaedic patients if it doesn't affect weight loss outcomes? Yeah, OK, so, so a very good point, I guess what I'm looking at for outcomes, you can judge various things in terms of an outcome, which is, do they, will they reach their target weight? Will they drop out too soon, and of course, how much and how fast, weight do they lose?
. What we, what we tend to do when we, we go for our weight loss, of course, is that we set the plan to get them to lose somewhere between 0.5% and 1% per week. If we find that their weight loss is slowing, we restrict the amount that we, we feed them to in order to ensure that weight loss happens at the same time.
So typically, when we look at outcomes, we won't see whatever the patient and almost whatever the strategy. The rate of weight loss is gonna be for successful patients is gonna be the same because we're kind of engineering it to be that. So when you then look at how much you've fed over the course of a weight loss plan.
If you take a patient that has orthopaedic disease. Versus one without where, where they started at the same amount, you've had to restrict the patient with orthopaedic disease more during that process. OK.
So that, that's where that evidence comes from that they typically need 5% less. Now we found that out about 10 years ago, when we did our initial review of patients. So what we now automatically do, knowing that is build it in at the start of the plan.
OK, so, so probably the short answer question is you don't necessarily need to, if they do well, you could just put them on the same amount if they're not losing, you can restrict them as you normally would. You will find that they will need less though. So I guess our argument is we cut out the middle man and we kind of just go, right, just get a bit less before.
I hope that makes sense. I probably didn't explain it brilliantly at the time. No, I think that makes perfect sense.
And, and of course, when they start losing weight, initially, you, you get better compliance if they see results, and it, it doesn't take much. So yes, so that's another, it's a very good point. That first month I always think is critical.
You want them to be losing weight because otherwise the owner might lose heart. And actually, having, having built that in, probably, I, I have, I can't prove it improves things, but, you know, logic would suggest that that would make sense. Yeah, I, I, I would, I would think so as well, you know, you've got to keep, keep at it, haven't you?
OK, that's great. The, the rest of the questions are more complex, so I think we'll add those to the panel at the end. So the gentleman ask the questions, so hopefully you can stick around all day.