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Welcome to the official podcast of the World Small Animal Veterinary Association, where we bring you conversations with leading veterinary experts from around the globe. Each season spotlights one WSAVA committee, sharing their knowledge, research, and insights through short, accessible interviews.
Every fortnight, we speak with two experts on a shared theme, offering concise, engaging discussions designed to spark curiosity and guide you toward WSAVA’s extensive library of educational resources, webinars, and events. Hosted by WSAVA President Jim Berry, the podcast delivers focused conversations that connect you with the latest thinking in small animal medicine worldwide.
You can find more educational resources from WSAVA here: https://wsava.org/education/
Jim Berry: Welcome to the WSAVA podcast. Today's discussion focuses on nutrition for chronic disease, specifically feeding for better control in diabetic and renal patients. Consider this, is nutritional management a secondary thought in your protocols, or is it a central pillar of your care? Our interviewer, Peter Higgins, speaks first with Scott Campbell and later with Lisa Weeth, let's listen in.
Peter Higgins: So this podcast is a really interesting one. We're gonna be talking about feeding a diabetic dog or cat and I find this really fascinating because if you look at the statistics, particularly from the AVMA in America, there's a number of dogs particularly that have, being diagnosed with diabetes, and when we talk about diabetes, we're gonna talk about diabetes mellitus just to be specific, they're on the increase and I suppose that's partly to do with animals ageing more and getting older these days. Certainly cats from what I've read too, with the same AVMA report. It's an interesting one, and nutrition obviously is a major component. It's not just a shove some insulin and hope for the best.
Scott Campbell: I think it's prudent to get an overview of the animal before you start getting into specifics. There's enough nuance between individuals with this condition that I think it is worthy of more consideration and it it'll help the results be better overall for that individual. It means that we're right more often, which always feels nice with the clients.
Scott Campbell: They seem to expect us to be right most of the time, all the time ideally, it's certainly one of these conditions where it's worth taking the time to get a bit of the background and we can all get different variations of this condition. Different severities, different timeframes that might affect body weight and body condition score.
Scott Campbell: So we have a few different things to mull over. We can have animals coming in and being diagnosed with diabetes and be pretty much asymptomatic. Or they can have those very typical signs where they're polydipsic and losing weight and lethargic and have poor wound healing, all that regular stuff. It's worth working out where they are in the spectrum, I guess.
Scott Campbell: This is probably a great time to put a plug in for the nutrition toolkit, in the WSAVA Nutrition Toolkit there's a bunch of resources in there that are relevant for this condition. Certainly, when you have any animal diagnosed with diabetes mellitus, you want to do an extended nutritional assessment for that animal.
Scott Campbell: There's a checklist that can help you to work through that. An important part of that is getting a diet history to work out what it had been fed prior. Sometimes that's great and sometimes it's not. And sometimes it can give you an idea of the animal's food preferences. It can give you an idea of calorie intake.
Scott Campbell: It can give you an idea of the owner's preferences. Also the feeding regime, how often it's fed, whether they're doing a lot of treats, what their activities like, what their home environments like. All of these things that are relevant to trying to control a complex endocrine condition like diabetes.
Scott Campbell: I'd encourage anyone not familiar with the nutrition toolkit to go and have a look because there's resources there on the nutritional assessment, but also body condition score, muscle condition score, feeding hospitalised animals, placement of feeding tubes, a bunch of other stuff that's not immediately relevant to what we'll talk about tonight.
Peter Higgins: So look, we've decided, we've done an overview. You've had your new graduate come up to you and say, what do we feed? What's the overall approach then now of feeding? Let's do a dog first. Because a dog can be different to a cat, can't it? So let's do a dog first. Are we talking about high fibre here?
Scott Campbell: There's some new approaches from folks like Linda Fleeman that are using the ultra long acting insulins now, the once day daily dosing. That's required a an alteration in our standard insulin feeding regime that we've been using for decades you and I Peter, where we were giving our Caninsulin, our porcine insulin, that 40 IU/ml we're all very familiar with and we were always doing twice daily dosing unless it didn't work in that individual.
Scott Campbell: Coming back to some of those resources, there are differences in how we're gonna feed that individual, depending on whether it's underweight or overweight, whether it has concurrent conditions, all of those sorts of things. But there are some similarities even between dogs and cats that we can talk about in that we always wanna try and feed a complete and balanced diet, dog or cat, sick or healthy.
Scott Campbell: We're gonna try and feed a commercial diet usually to our diabetic animals because they're more consistent. When you're feeding home prepared diets, there's always variability in the ingredients, variability in the preparation, the chance for selective eating by the individual animal. So commercial diets that are completely balanced are generally preferred for these conditions where you've gotta be methodical, predictable in the nutritional uptake by the individual animal.
Peter Higgins: Let's talk about that consistency, because the consistency of how and when you feed is as important as what you feed. So the consistency of feeding at the same time of day, that's what you mean by consistency, isn't it?
Scott Campbell: Yeah, well, consistency in the nutritional makeup of the food, and also consistency in the feeding strategy.
Scott Campbell: The feeding strategy will vary depending on the type of insulin we're using and the species, we'll really burrow down on those dogs and cats because that's where the big differences are in some of the new information that's come out over the last couple of years has really given us new direction on some of that.
Peter Higgins: Before we talk about the differences, let's continue on with the commonality. You've mentioned consistency, both of the diet itself.
Scott Campbell: Yeah, the diet and the feeding strategy. You would've seen in clinical practice, Peter, that those owners that are very dedicated and very regimented with their approach consistently get better results.
Scott Campbell: It is critical, I think. The general overviews, we want to be aware of dietary carbohydrate because that's gonna get metabolised to glucose. We want to try and maintain or achieve an ideal body condition score, so if they're underweight, we wanna feed a few more calories to try and get that weight back up. If they're overweight, we wanna gradually reduce calorie intake to try and get back to an appropriate body condition score.
Scott Campbell: We want to compensate the higher nutrient requirements, and I'll talk more about that with individuals because it does go a little bit different with dog and cats and then again, current conditions, avoid making rapid diet changes. That's for every unwell animal in a stressful environment like the hospital, we wanna try and avoid making rapid changes to diet because that's where we can get these learned aversions. So they're probably the commonality covered.
Peter Higgins: We have spoken about consistency quite a bit now. Anything else with an overview of both dogs and cat species before we talk about anything specific?
Scott Campbell: Well, I think we've hit the big points, and it's a really nice segue because if we start by talking about dogs, they're the ones where consistency in diet strategy or diet approach, feeding strategy is probably the most important point. So if you're happy, Peter, I might yarn a bit about that.
Peter Higgins: Why don't we talk about dogs? What's your approach to feeding dogs with diabetes? And then we'll talk about cats because it is different. What's your thinking? Fibre is something that's been spoken about quite a bit.
Peter Higgins: What are your thoughts on all that?
Scott Campbell: Fibre is certainly part of the conversation. It's probably further down the list for me than a bunch of other things. First thing I always think about is water. It's the most important nutrient, and particularly for diabetes, where they have higher water intake. Water's always the first one.
Scott Campbell: You've always gotta have clean, fresh water available for diabetic animals. That's point number one for me. The second is somewhat variable. It dissipates a little bit depending on whether we're gonna use that long acting insulin and if you're using the once a day insulin, the timing of the feeding can be important to try and match when the greatest insulin actions required that can be individual with that animal.
Scott Campbell: You have to play with that a little bit. Sometimes reduction in the carbohydrate content or the digestibility of the carbohydrate can be important. Some dogs do better with feeding small meals more often to stop that huge glycemic load from hitting the bloodstream all at once. For those guys, the once a day insulin dogs, if that's a, a strategy the owner wants to try or that individual can't manage twice a day, they're the ones where I have a few different approaches to try. And sometimes I want an idea of the blood glucose movements over a day or two, to try and, and that's easier now than it used to be, Peter, with these continuous glucose monitors, we can get an idea of how that individual reacts to the insulin type and dose. Then we can make our dietary recommendations to match that insulin action. If we go back to the more conventional way that you and I have been doing it for decades, using the twice daily insulin, as we talked about, consistency is the most critical thing.
Scott Campbell: I think you can regulate most dogs, any complete and balanced canine diet can be used, all you have to do is give the same amount of insulin and the same amount of food at the same time every day, and you can match those two together. If you're giving a diet with a little bit more carbohydrate and you give a little bit more insulin, it generally works out.
Scott Campbell: So we talk about the three sames, the same amount of the same food at the same times every day. And if you can get those three things the same and then match your insulin type dose timing to be appropriate, then that tends to be something that works really well together in a majority of dogs. So normally we'd be eating immediately before the insulin because if the animal doesn't eat, that can prompt us to not give the full dose of insulin.
Scott Campbell: Similar to what we would do if they were vomiting or fasting before surgery or something. I do a half dose. There's probably more specific recommendations around that, but that's what I've always done.
Peter Higgins: There are very scientific and mathematical calculations, but I'm gonna be like you in practice. I usually just give a half dose.
Peter Higgins: So if I think an animal's likely to become hypoglycaemic for whatever reason it is,
Scott Campbell: yeah.
Peter Higgins: either they're not eating or they're purposely fasted, I'd just go half dose and I haven't had a problem with that at all.
Scott Campbell: We might get feedback from someone that we're doing it wrong, but that's probably more a medicine question.
Scott Campbell: I've always done that, but I do tell owners, you are always better to be a little bit diabetic than a little bit hypoglycaemic. If they choose to skip it for a morning or something, then that's not the end of the world either.
Peter Higgins: Is there anything else that you wanna say about dogs before we talk about our feline friends?
Scott Campbell: I think achieving and maintaining an ideal body condition score. Again, I know we talked about that as a general thing, thinking about concurrent disease states. Bringing in diet changes slowly, monitoring them closely to make sure that they're palatable and tolerated by the individual. Being aware of that caregiver response, the burden and the cost constraints that they may have, have that flexibility in your approach to work with the client and if your first strategy doesn't work, to have backup plans that you can reach for.
Peter Higgins: Alright, so let's move on to our feline friends, what we're gonna talk about with cats. So what's your approach to the differences between dogs and cats with diabetes?
Scott Campbell: Diabetes has genuinely evolved over the last 20 years, over the last decade, over the last five years, over the last 12 months, and it, it is continuing to develop and change, and I think there's more to come here yet, but it's an exciting time to be talking about it. Probably 50% or more of our cats with diabetes probably don't need insulin.
Scott Campbell: It can be managed to get to a condition where they can resolve their diabetes, certainly short term, and maybe long term by getting dietary modification right. The importance of nutrition in a number of conditions, but absolutely with cats and diabetes has been revisited and being a really profound reawakening of how it can impact our cats.
Scott Campbell: This is an exciting subject. No doubt.
Peter Higgins: I think cats with diabetes is an exciting area. The management is different and the species is very different. What are your approaches? High protein diets and low carbohydrate diets, that's generally speaking, the right approach, isn't it?
Scott Campbell: It is, the initial terminology that came out was high protein.
Scott Campbell: High protein is important, and we know cats have a higher protein requirement compared to dogs and people, and they have that because of their evolutionary adaptations that they've made where they've down regulated some of the enzyme systems that would otherwise let them get away with less. So we know that is built into the species.
Scott Campbell: The more important thing with cats for diabetes is we want low carb because we feed with those three macronutrients, protein, fat, and carb. The emphasis with diabetic cats should be on low carbohydrate rather than high protein. In cats in general, high protein, yes, but for diabetic cats, low carbohydrate, trying to keep that carbohydrate level less than 12% on a metabolisable energy basis, or less than three grammes per hundred K cals.
Scott Campbell: And that can be higher fat can be higher protein, but definitely low carb is the critical bit. Other changes, higher moisture, making sure it's complete and balanced, making sure it's palatable to the individual. They're all very important changes as well, but really that low carbohydrate we know can be really critical if we want to try and regulate these guys and get them back into remission.
Peter Higgins: In terms of cats, you mentioned palatability quickly. What's your practical advice with owners where they go, Mogie here just refuse to eat this stuff, what do I do? How do I feed her? She doesn't think it tastes very good.
Scott Campbell: I think we have less issues with the diabetic diets because they tend to have higher levels of nutrients, protein and fat that are more palatable.
Scott Campbell: So I think we have less issues with these guys, but I think patience and slow introduction, really close monitoring of those individuals. And if a specific diet doesn't work, we're blessed to have a few options from different therapeutic diet manufacturers at this stage. So slow introduction, trying to do it in a home environment or an environment that is not threatening, not stressful, warming food up, changing the consistency by making it a slurry, adding water.
Scott Campbell: They're all little tricks that we try along the way. Some of these guys, if they won't eat the diet that they need, sometimes these are the ones that you need to put an esophagostomy tube in to help them in the short term to get around it, and that's something you have to have in the back of your mind.
Scott Campbell: But in this specific case with diabetics, general feeling with that is that it's less of an issue to get them to eat the diets that are recommended.
Peter Higgins: In terms of that, let's bring that out into the open. I guess we're talking more these days about commercial foods, aren't we? It's very hard to do a homemade diet for a diabetic animal, particularly a diabetic cat, I would've thought.
Peter Higgins: Would you go along with that thinking in general? Without promoting any particular brand, we don't wanna do that, but in general, the commercial foods would be the way to go with this.
Scott Campbell: Yeah, I think so. More consistent. They've got variations where it's not just carbohydrate content, they're gonna have the right level of protein, the right digestibility, they're gonna potentially have some fibre in there.
Scott Campbell: You've gotta be really careful with fibre in cats. Cats don't do well with too much fibre. They're gonna have higher levels of those electrolytes and those B vitamins and things that might be lost with the polyuria. So it's not one specific change. There was a tendency to go for over the counter foods that are low carbohydrate, and certainly they might have that specific nutrient modification, but they might not have some of the other changes that we just talked about that can be relevant for some cats for sure.
Peter Higgins: Alright, so look, a question I get asked is, I'm happy to feed whatever you tell me to, but can I, can I give fluffy some treats? And what are your thoughts on that?
Scott Campbell: Along with weight stability and an absence of clinical signs, we should be talking about diet and feeding strategy and making sure the owner's happy with it each time they come in for their follow-ups. We have to think about the extremes of diabetes. If they come in with diabetic ketoacidosis, obviously they need a lot of stabilisation before we go back to our standard feeding regime.
Scott Campbell: Commercial treats are made to be tasty. Particularly for dogs, they're often very high carbohydrate and rapidly assimilated high sugar, and they make management of diabetes a a bloody nightmare in my experience. If an owner absolutely insists on giving a treat because it's part of their routine, I will try and talk them out of it, suggesting they give affection and attention as a treat, play as a treat, all these other interactions as a treat to build that human animal bond.
Scott Campbell: If they really want to do it, I will try to get them to use a portion of the base diet or at at the very least, try and get that consistency built in the same amount of the same treat at the same time every day, minimising the calorie load. So all of that becomes part of the discussion and the risk is really highlighted for the owners because variation is not our friend.
Peter Higgins: I agree. I've enjoyed talking to you, Scott. It's been informative. I hope people listening have got some good information outta this, both theoretical and practical.
Scott Campbell: Great and likewise, Peter, it's always good to have a chat. Hopefully we got some information that's of use across as well.
Jim Berry: After Scott Campbell, Peter Higgins and Lisa Weeth continue the conversation on nutritional interventions for renal health.
Peter Higgins: Renal disease is prevalent in both dogs and cats, particularly cats, we all know that the feeding of dogs and cats really one of the most crucial things you can do for the management of it. We're gonna talk a little bit more about that with Lisa. But Lisa, I guess there's two objectives with chronic kidney disease.
Peter Higgins: One is to lower the amount of nitrogenous waste that's produced by protein metabolism. And the second thing is minimising the actual amount of protein that's being pumped through the glomerulus of the kidneys. So we won't talk too much about drug interaction because we were talking about nutritional impact today, but what are your thoughts on how we control those two objectives?
Lisa Weeth: Thank you for having me on this podcast recording today. And so talking about renal disease, it really depends on the stage of renal disease the patient is at. I think humans in general, we take mental shortcuts. We've got a disease we're trying to match. We're just gonna fit that diet into that box. It's just renal diet.
Lisa Weeth: The challenge is there's not one form or one type of renal disease that dogs and cats will get. When we talk about the different nutrient modifications, we need to focus on the patient. My approach as a nutritionist is I always put patient first. I have an idea of what I wanna modify for a particular disease condition, but then I look at that dog or cat. So protein restriction is important if we have an animal that has an elevated BUN, so that blood urea nitrogen level is up, that's telling us their kidneys can't handle the amount of nitrogenous waste products that are being produced. So we need to lower the amount of protein coming in the diet.
Lisa Weeth: We're trying to alleviate the workload of the kidneys. So that would be one reason to restrict protein. The other reason to restrict protein is if we have a patient that has protein losing nephropathy, even if serum nitrogen levels are fine. They're normal. If there's significant amount of protein in the urine, that tells us that glomerulus, that upper part of the nephron is leaky, and so larger proteins are able to make their way out.
Lisa Weeth: What pushes pressure through the glomerulus is the amount of protein and nitrogen waste products. The more nitrogen you have, the more flow you're gonna have through those nephrons. And so you wanna, again, we're trying to reduce the workload to the glomerulus, but for a different reason. We're trying to reduce pressure in the glomerulus rather than the product going in.
Lisa Weeth: For those cases that have significant proteinuria, we wanna reduce the amount of protein because we're decreasing the pressure. It's the same effect that if we give an ACE inhibitor, if we give something like Benazepril to these dogs, we're trying to dilate the outflow to reduce pressure. By lowering the amount of protein in the diet, we're reducing the amount of pressure that's being created endogenously in these animals.
Peter Higgins: The amount of protein, obviously, is an important factor. What about the quality of the protein? This podcast series we've spoken about protein quality. Where's the protein quality fit into the chronic renal disease?
Lisa Weeth: What we need to remember is that the requirement for protein, where they're talking about a dog or a cat, varies.
Lisa Weeth: Cats are carnivores. Their protein requirement is higher than a dog. So if we look at the diet and look at the percentage of protein calories coming into that diet for a healthy adult cat, I'm looking for probably a minimum of about 30% of those calories. Bare minimum is closer to 20%. Our renal diets for cats, the protein levels are usually between 20 and 30% of the calories, like 22 will be on the low side, 28, some of the early renal diets are right at that 30% mark. Minimum requirement for cat closer to 20% of the calories. None of our renal diets for cats are below that level, so all of them are meeting the minimum protein needs and that's where protein quality comes in. If you have a diet that is limiting in protein, make sure that protein has a complete amino acid profile.
Lisa Weeth: So all of those essential amino acids, the building blocks of protein, need to be in that protein at the right amounts and the right proportion. Protein quality depends on the digestibility and the bioavailability of that protein. So if you've got a really clean protein that it's easy for the body's digestive system to break down and absorb as those amino acids, it's gonna be much better than if you have a poor quality.
Lisa Weeth: And usually quality for proteins comes down to how it's processed going into the diet and what it's cooked with. So if you have a protein that say is a chicken meal, that's a dehydrated de fatted chicken protein. So it's not too dissimilar from like protein powders that people put into smoothies and shakes.
Lisa Weeth: It's just chicken sourced instead of soy sourced or dairy source. So if you've got a chicken meal that has a chicken protein powder, that's a lot of muscle chicken meats. That's gonna be a really high quality chicken meal. If that chicken meal is mostly the grisly bits that are more collagen and chunks of bone.
Lisa Weeth: It's still gonna look like chicken meal on the label, but that's a poor quality protein because the amount of actual protein in that ingredient is lower relative to the cartilage, relative to the bone. So you won't know that as a consumer looking at the label, this is where knowing your manufacturers comes in.
Lisa Weeth: So if you've got a therapeutic diet, it may have a lower protein level on the label, but they're using better qualities of protein that have more of those essential nutrients in them, so you can get away with it. Anything above the minimum requirement for protein, anything above those minimum needs, it's just waste.
Lisa Weeth: Like there's no protein stores, so giving extra protein doesn't make you build more muscle. It just means your kidneys are working harder.
Peter Higgins: Protein quality is an interesting point though, isn't it? If we look at buying commercially prepared foods, they talk about protein quantity and they talk about ingredients.
Peter Higgins: The the quality, you mentioned that some consumers would not know. I would go as far to say that there would be some practising vets that don't really think enough about protein quality as well. If it's poor quality, then it could actually do damage, could it not?
Lisa Weeth: Exactly. At least in the early stages, if what you're looking at maintenance foods.
Lisa Weeth: Once your patient's been diagnosed with renal disease, then I start looking at the stages. Is it an IRIS stage, International Renal Interest Society, stage one where clinically biochemically, everything's fine. There's just something that's flagged our attention. We do an ultrasound and there's one kidney that's abnormal looking, or they had a ureteral lift, and we know there's been an insult.
Lisa Weeth: We've gone from a hundred percent of renal function below that. For me, stage one animals are just we have evidence that there's something not working at a hundred percent of those kidneys, but we don't necessarily need to make big changes. Those are the animals where like I, I don't know that I'm so much worried about protein quality, like I still want a high quality protein, but I'm focused on that mineral level in the diet.
Peter Higgins: So when we talk about IRIS, that is a, a good thing to bring up now 'cause you've already mentioned it depends on what stage of the renal disease that a dog or a cat is in, in terms of managing those stages of IRIS. Then you would say in the early stage, the protein quality is less important, but quantity is?
Lisa Weeth: Yeah, we want good quality proteins in our food.
Lisa Weeth: Like we don't want our animals eating ingredients, they're just end up as waste products.
Peter Higgins: Pieces of leather.
Lisa Weeth: Yeah. Yeah, I mean, it's really expensive poop. You want something that's a good quality protein, but it's less of an issue when you're getting plenty of protein in the diet. So again, minimum requirement for cat 20% bare minimum. If I'm like looking at a renal patient, adult maintenance foods are usually 30%. Dogs, it's a little bit lower. If their current diet is really high protein, say it's 50% of the calories coming from protein, maybe we wanna start sneaking in some carbohydrate. We might wanna start shifting their flavour and preferences and food preferences.
Lisa Weeth: If they're an IRIS stage one cat or an IRIS stage one dog, at some point they will progress. Cats will progress and become more clinically affected with a renal disease. Dogs, I feel like dog kidneys are a little bit more forgiving for us unless they're proteinuric. Again, like if they've got protein losing nephropathy, we can predict this is going to progress in a certain amount of timeframe.
Lisa Weeth: So four or five years we're gonna end up with overt renal disease. We're gonna have an animal that's more clinically affected. If it's that 12-year-old dog whose kidneys are not at a hundred percent, they may never progress past that. With age related acquired kidney disease, if it's just decreases in tubular function, those dogs tend to be stable for years and oftentimes they end up dying with their kidney disease, not because of their kidney disease. I feel like we need to know the patient we're dealing with. Is it a cat? Is it a dog with protein losing nephropathy where we need to be a little bit more aggressive?
Lisa Weeth: Or is it that 10-year-old dog who's just a little isosoneric and maybe they're creatinines at the high end of normal. We need to avoid excessive amounts rather than start thinking about restricting. But for me all of those dogs, at some point we may, or cats, we may have to change the diet. So I want them to start eating a profile that's a little bit more balanced in its macronutrient profile.
Lisa Weeth: So protein, fat, carbohydrate may be a little bit more even across the diet. That way if we have to make big changes, it's not a shock to the owner or to the patient because if you have a a cat that's on a high protein meat-based diet and then they progress from stage one to stage three, where now we've got an IRIS, stage three cat who's starting to show some of those clinical signs of their renal disease, appetite's getting a little bit fussy.
Lisa Weeth: They're losing weight. Owners feel like they're yo-yo chasing their appetite. Now we're trying to introduce a higher carbohydrate, lower protein diet. The cat's gonna look at you like, are you crazy, man? And the dog's gonna look at you like, what did I do? I'm such a good boy. And so we wanna start thinking about the future, and that's how I approach diet.
Lisa Weeth: We're not just feeding the animal right then and there at that moment in time, we're feeding them for their lifespan. Phosphorus really impacts the quality of life. For an animal with renal disease, but phosphorus is what can influence how quickly it progresses. So the higher phosphorus level we have in a diet, especially for a cat, we know that it's gonna cause dystrophic mineralization.
Lisa Weeth: We're gonna end up with tubular damage and we're gonna ultimately cause a progression. So for me, when people start arguing about cats with kidney disease, they're old cats. They lose body mass. We need to keep an eye on protein, brings a lot of phosphorus with it, and if we keep them on a high phosphorus diet, we are going to accelerate their kidney disease.
Lisa Weeth: We know that. Lots of published studies showing that phosphorus causes progression of kidney disease. So we wanna keep an eye on that. And again, we're not necessarily restricting below the requirement. We just wanna avoid those excesses. So I try to encourage veterinarians and caregivers who are managing animals with renal disease to really think about it in, not that we're taking something away. When we use the term restricting, it feels like it's almost like a punitive effect. We're not restricting below a requirement, we're just avoiding that excess. So we're trying to reduce the workload of the kidneys so they can work better for longer. If we've got that base, we know how much protein the animal can tolerate and handle, and we know how much phosphorus we can tolerate and handle, then I start layering on those other nutrients.
Lisa Weeth: So Omega-3 fatty acids, so long chain Omega-3.
Peter Higgins: Just before you do talk about Omega-3 fatty acids, we're going through this in quite a structured way at the moment. Is that how you would approach it in a clinical situation where you would say protein first, then phosphorus and then other nutrients like Omega-3 fat?
Lisa Weeth: I actually think about phosphorus first, then I think about protein. A lot of caregivers think about protein first because that's the meaty part of the diet. There is even a lot of clinicians who think about protein first. They're thinking about older animals that may have sarcopenia, muscle loss associated with their ageing, advanced renal disease.
Lisa Weeth: We know that high levels of urea can have a catabolic effect on muscle mass. We know that it can cause lean body mass breakdown. Some people think, well, if I add more protein in, that'll counter that. But if it's your animals a azotemic it's actually gonna make it worse. If your animal is proteinuric and you add more protein in, you're just gonna worsen the workload of those kidneys and you're gonna push more protein out through those leaky glomeruli.
Lisa Weeth: So I think about phosphorus first, but phosphorus and protein almost go hand in hand. Sometimes I'll adjust my conversation depending on who I'm talking to and what their primary focus is, but those are the two.
Peter Higgins: The reason I ask that, Lisa, is that I, I would suggest there's quite a lot of practitioners that think about protein first.
Peter Higgins: I was lucky that when I went through university, we just had amazing teacher and he always advocated phosphorus first as well, and that was more than 10 years ago. So I just wanted to get your views on that and to see whether that phosphorus, protein, other nutrient kind of approach is, is a good clinical approach.
Lisa Weeth: That's the way I think about it because phosphorus at any stage, stage one to four, we need phosphorus restriction or at least phosphorus control. I don't start restricting until we get into stage three and four, and that's when we really, especially for dogs, we may actually reduce the phosphorus below the minimum requirement.
Lisa Weeth: Until that point, we're focusing on a serum phosphorus level as well. We're trying to keep the serum phosphorus less than 4.5, and anyone who wants to look at the IRIS staging, that is the cutoff. There's been clinical studies that show serum phosphorus is greater than 4.5, tend to accelerate the disease a little bit faster than if it's below 4.5.
Lisa Weeth: So direct correlation and direct causation with the phosphorus levels, I think about phosphorus first because that's what's gonna impact the longevity of that animal and the longevity of those kidneys.
Peter Higgins: I'm pleased you said that because that's the way I approach it too.
Lisa Weeth: Yeah and I want my patients to be with me as long as physically possible 'cause I want them to be with their family for as long as possible. So that's where I focus on good quality years together.
Peter Higgins: What about other nutrients? What about Omega-3 fatty acids?
Lisa Weeth: So Omega-3 fatty acids, what we're really talking about is EPA and DHA. Those are high in cold water fishes. EPA and DHA are long chain Omega-3 polyunsaturated fatty acids that get incorporated into the cellular membrane.
Lisa Weeth: It's been shown in dogs and cats with kidney disease that higher EPA DHA levels actually help support blood flow and function of the kidneys. We know that higher levels of EPA and DHA can help with allergic dermatitis, so it doesn't just target the kidneys, it gets into the skin. Gets into every organ system, the GI tract, the brain.
Lisa Weeth: DHA helps support nerve function and brain health with ageing. So there's a lot of reasons to incorporate more EPA and DHA into the system other than just the kidneys. A lot of our older patients with kidney disease have comorbidities that we need to support.
Peter Higgins: We've covered a few things. Is there anything that you want to add in?
Lisa Weeth: Yeah, the one thing I would add is when we're looking at renal disease, if we have those more advanced stages, a renal therapeutic diet is more than just protein, phosphorous, Omega-3 fatty acids. It's sodium control. It's increases in B vitamins. These animals are polyuric. They're losing B vitamins at a faster rate, so we need B vitamin increases in their animals with more advanced renal disease tend to become acidotic. Their kidneys are important for acid-based balance, and so there's also pH effects of the diet. So it's not as simple as, I'm gonna grab a lower protein, lower phosphorous diet over the counter, if it also hasn't accounted for all the other nutrients. Feeding renal patients is not as simple as just protein phosphorus rejection.
Lisa Weeth: There's a lot more that goes into it. Is this the right diet for my patients? I'm thinking about quality of life. I'm thinking about quantity of life. How long? We want more years together.
Peter Higgins: Lisa, I've really enjoyed this.
Lisa Weeth: Always good to talk to you, Peter.
Peter Higgins: Dr. Lisa Weeth, thank you for updating us on the nutritional requirements of dogs and cats with renal disease.
Jim Berry: Thanks for joining us on the WSAVA podcast, where we are transforming care, one episode at a time. We hope today's discussion was helpful, wherever you are in the world. You'll find further resources in the show notes and we look forward to sharing our next conversation with you soon.