February 14, 2019 – Dr. Kelly Diehl talks about mitral valve disease in dogs with Dr. Kate Meurs, Professor and Associate Dean for Research and Graduate Studies at the North Carolina State College of Veterinary Medicine. Dr. Meurs discusses her Morris Animal Foundation-funded study to identify genetic mutations to recognize dogs that would be at risk for developing the disease, and how veterinarians might intervene.
00:17 Dr. Kelly Diehl: Welcome to Fresh Scoop, Episode five, Mitral Valve Disease in dogs. I'm your host, Dr. Kelly Diehl, Morris Animal Foundation's interim Vice President of Scientific Programs. And today I'll be talking with Dr. Kate Meurs, Professor and Associate Dean for Research and Graduate Studies at the North Carolina State College of Veterinary Medicine. She also is a Morris Animal Foundation funded researcher. For those of you who may be new, fresh scoop is the monthly podcast of Morris Animal Foundation, the largest non-profit foundation in the world dedicated to funding studies that find solutions to serious health threats in animals.
00:58 DD: Founded in 1948 by Dr. Mark Morris senior, a veterinarian, we've invested more than $126 million in more than 2600 studies that have improved and protected the health of companion animals, like cats, dogs, and horses, as well as wildlife. In each episode, we feature one of the researchers we fund or one of our staff members discussing their work in advancing animal health. Whether you're a practicing veterinarian, technician or a student or just an animal loving science geek, Fresh Scoop is the podcast for you. You can learn more about us at morrisanimalfoundation.org.
01:38 DD: Okay, on to today's show. Today, we welcome Dr. Kate Meurs. Dr. Meurs is a DVM and PhD, and she is here to talk about a recent study that Morris Animal Foundation funded on mitral valve disease in dogs. Welcome, Dr. Meurs.
01:55 Dr. Kate Meurs: Thanks so very much for that fabulous introduction and I have loved every minute of working with the Morris Animal Foundation, I've really felt incredibly honored to be, I like to thinking myself maybe a little bit part of the family and have been on the scientific advisory board twice. That's why I eagerly went back. I just think it's a great organization. So, thanks for the kind introduction and thanks for allowing me to be part of the Morris Animal Foundation family.
02:24 DD: We love having you and just for our listeners, I often have to reach out to Dr. Meurs for all kinds of heart questions and she's been just super with it. So to start off, can you tell us a little bit about how common heart disease is in dogs?
02:44 DM: That's a great question. Overall, I can't say, I don't know the statistics of the actual prevalence of heart disease compared to kidney disease and cancer, and other things that animals get. Certainly heart disease in elderly dogs and middle aged cats is increasingly common. But what percentage it makes up of the overall pet population, I don't actually know. It certainly keeps cardiologists busy, There're roughly 300 boarded veterinary cardiologists just in the United States. So it's a busy enough need that we're able to have quite a few of us out there.
03:32 DD: Okay. And I know this question is going to be a little tough but you can keep it general. What are kind of the most common types of heart disease, big categories, that you see in dogs?
03:45 DM: So in dogs, the biggest heart disease for sure is what we call valvular degeneration, and that's where one of the heart valves, generally on the left side of the heart, suffers some changes as the patient gets older and so it starts to leak. That's actually the most common heart disease that veterinarians see, whether it's dogs or cats, but that shows just how common it is. And so, that's overwhelmingly at the major disease. We also see a heart muscle disease in dogs called dilated cardiomyopathy, that's where the heart muscle gets weakened and doesn't contract quite as well, doesn't pump as well as it used to. We tend to see that more in large breed dogs, like Doberman Pinchers and Great Danes, whereas this valve disease tends to be much and seen more commonly in smaller dogs. And as an example, I had wonderful cardiology professor, Dr. Bob Hamlin, who's out of Ohio State University and years ago, he taught me that if it's a dog that you can pick up with one hand and it has heart disease, to think about valve disease; if it's a dog that would take two hands to pick it up on the table, and it has heart disease, it's probably a heart muscle disease. So that's a way of helping me remember that big dogs and little dogs tend to get different types of heart disease, although there is little overlap.
05:12 DD: Okay. So thanks, and I'm going to move into a specific disease and I just want to let our audience know that Dr. Meurs is our Mark Morris Jr. career Recipient Award winner, and this was a grant that was, Dr. Meurs is the first recipient and it was designed a few years ago with the goal, by the Morris family, with the goal of trying to find a very common disease in either dogs or cats that we could move the needle on if we had a researcher of high quality who had time to work on a particular problem and Dr. Meurs was the winner, I guess you're the winner of that particular award. And it is focused on what Dr. Meurs just mentioned, which is mitral valve disease, again, the most common heart disease we see in dogs. So, we'll focus in on that and then we'll talk about your research. So, what can you tell us, Kate, about mitral valve disease specifically? You talked about it's smaller dogs but can you talk a little bit about breed and sex and when you see it?
06:26 DM: Yeah. So there are some common breeds. We tend to think of miniature poodles, dachshunds, the Cavalier King Charles Spaniel, chihuahuas, Yorkies, as being some of the very most common, but really almost any small breed dog, shelties, Lhasa Apsos, toy poodles, are at risk of it. And because it is so common in a large variety of small breed dogs, you also do see it in the mixed-breed dog. So if somebody has bred a cockapoo or this is a dog you took in from the shelter or, perhaps, your cousin convinced you to take it and they saw it out playing in the yard when it was an abandoned puppy and it was a small-breed dog. Even if you don't know its family, those are all dogs that are at risk at developing this disease. And in some breeds, like the Cavalier King Charles Spaniel, it can start as young as three years of age, but more commonly it starts at middle age in a dog, so six, seven, eight years of age. Sometimes it doesn't start until even later.
07:44 DM: We've been looking, as part of this research project, through the Mark Morris, Jr. Award, we've been looking at breed differences, and we've noticed that miniature schnauzers sometimes don't develop the disease until, say, 11 years of age. We're just finishing a new publication that we were submitting that is out of this research, just looking at the disease in miniature poodles, and they tend to develop the disease around 10. So there is differences across the breed of when they develop it, but basically that heart valve degenerates a little bit. You might almost think of sort of the same type of processes that you think of is with arthritis. It's a degenerative process, but in this case it's of the heart valve. And when it does that, that valve no longer closes correctly and it starts to leak, and therefore it starts to leak blood backward into the chamber above it, which is the atrium, and then it leaks blood eventually backward into the lungs.
08:49 DM: So what you would see with your dog at home would be that the dog might start coughing as the heart stretches and dilates and as some fluid backs into the lungs. Your veterinarian may recognize the disease when they put their stethoscope on they hear some additional turbulence in the heart, which is what they call a heart murmur. And that is often the first sign that your dog may have this disease is either a veterinarian hearing that new heart murmur or you pick up this clinical sign of a persistent cough that doesn't seem to get any better in your dog at home.
09:32 DD: Okay. And is mitral valve disease treatable and how do you typically treat this condition if you diagnose it in a dog?
09:41 DM: Yes. So the real treatment would actually be a valve replacement or valve repair, which we can do in some extenuating circumstances in dogs, but it is extremely expensive, probably about $30,000, and it's a very risky procedure because it's basically an open heart procedure, So, although that can be done in dogs, it is rarely performed. Instead what we do is try to manage the heart's capacity to deal with that leaking heart valve, and that's with medications, pills that the dog would receive, and there's very good evidence now that starting your dog on medication before they develop a lot of clinical signs can actually slow the progression of the disease and increase life span.
10:36 DD: So, what we recommend is that if someone has a dog that has a persistent cough, that be evaluated by their veterinarian to see if it is this disease, and if that veterinarian has heard a new heart murmur on their annual exam, that they take an X-ray or get a cardiac ultrasound, or echocardiogram. But often an X-ray is a very good way to start. If there is heart enlargement on that X-ray or the cardiac ultrasound, which is also called the echocardiogram, at that point it probably is time to start medications, and that would be with drugs, something called Vetmedin, which is also called pimobendan, or a drug called Enalapril or Benazepril, those ACE inhibitors. And there's good data to show that even if they don't have any symptoms, so they're not even coughing, but your veterinarian hears that murmur and shows they have a large heart, or if they're just beginning to cough and they have a large heart, that starting them on medications at that point is really the best time to intervene because you can have the biggest impact.
11:45 DD: Okay. So it sounds like early intervention is associated with a better prognosis long term.
11:55 DM: Yes.
11:56 DD: Okay. And so I think you alluded to this, is... because I bet you there are a lot of listeners out there who have leaky valves, I think it's pretty common in people. So is this disease similar to human valve disease or is it unique, different, than what we've seen people?
12:14 DM: There are a lot of similarities to the disease in human beings and so we tend to use the human medical literature, the publications and scientific data on that, to help us think more about the disease in dogs. But it is not identical. So there's similarities, but there are also some differences if you looked at the heart valve, under a microscope, for instance. But overall if you do have a leaky heart valve at home, the type of medications that your physician may have recommended for you would be very similar to what your dog was being prescribed.
12:57 DD: Okay. So I have a question. Why did you decide to do research on this particular disease? We'll talk more about, specifically about, your Mark Morris, Jr. Award. But what was it, and it can be personal and professional, that propelled you to look into this more?
13:15 DM: Yes. So as a veterinary cardiologist, I have some frustrations that we see a lot of heart diseases that we can't cure, that once you have a heart problem unless you had a heart transplantation, we cannot fix that problem. And so I'm very interested in trying to understand why patients get the heart diseases that they have, because I believe that if you understand why those diseases develop, that you are going to be able to do a better job to prevent them, or to choose medications for them. So, we tend to choose medications for this particular heart disease, based on what happens when they have a heart that has gotten enlarged secondarily to this disease. And I believe that if we knew more about the underlying process that started the disease, that we might be even more effective at choosing the best medications for it.
14:22 DM: And because this is such a common Heart Disease, again by far the most common heart disease that any veterinarian in small animal practice sees, for many people that don't have a large income, and maybe can't come to a specialty hospital, their general practitioners is trying to help them as well as they can with this disease. And so, I am hopeful that this is an area where we can have a big impact. If we really understood this disease better, all of the general practitioners who are on the front line of working with you and your dog about this heart disease might be able to help you do a better job, keep that dog feeling comfortable longer. Maybe have a really profound impact on it but we need to understand the disease better.
15:12 DD: Okay. So using that as a lead in, can you briefly describe the Mark Morris Jr. award study, and a little bit about the methods you're using and what you're looking for?
15:28 DM: Yes. So, this study was funded to actually try to identify genetic causes of this disease. So, again, as a cardiologist when I thought about trying to prevent some of these diseases, it became clear to me that many heart diseases in dogs, and sometimes in cats tend to be inherited. We see them in certain breeds of dogs and certain families. And so I developed a strong interest in trying to identify the genetic mutation of diseases. And that's not just so that then you could have a genetic mutation and breed it out of an animal, but just as well that if you knew that someone came to me with their new Schnauzer, miniature Schnauzer puppy at 12 weeks of age. If I knew the cause, the genetic mutation that led up to valvular disease in that dog, and I tested that puppy and he had a genetic mutation, could we make medical interventions even at that point to make a difference in the life span of this dog?
16:37 DM: And so that's really what the point of this research and this award is, is we know, I mentioned to you that we know that once a dog's heart is big, that we know that intervening with medical therapy there can slow down the progression of disease. If we knew even earlier, maybe when they are a 16-week-old puppy before they're showing any signs of cardiac changes. If we knew then that they were going to develop this disease and we intervened then, could we make an even bigger difference. So the point of this project is to try to identify genetic mutations and a genetic test to identify dogs that would be at risk of developing this disease, and then to try to figure out how to intervene.
17:28 DD: Okay. So, you talked a little bit about the papers you're submitting but what are you finding so far in your study, in this particular award study?
17:42 DM: So, even though this disease is very common and we see it in many small breed dogs, it turns out that it is not identical. So, we initially had thought that there may be one genetic mutation that causes this disease and maybe miniature poodles have the same as miniature Schnauzers do, and as you pointed out, since the disease is common in people too, maybe dogs and human beings share mutations. So, so far, what we've discovered is that the genetic mutations that cause the disease in people are not the same as in dogs. So the human mutations that lead to the disease are not found in dogs with this disease, and also that it seems very unlikely that they... That all small breed dogs will share the same genetic mutation, it's likely that they each have developed their own mutations. So we're really focusing right now on trying to characterize some of the different breeds.
18:43 DD: So, what does this disease really look like in a miniature poodle compared to what it really looks like in a dachshund and what it looks like in a Chihuahua, rather than thinking of it as one single disease that we see in small breed dogs, more likely the miniature Poodle has one version, the Yorke has a different version, the disease is similar, and right now in 2018 we prescribe them the same medications. But probably it is caused by a different genetic cause, and it is slightly variant. And that's why they also tend to develop it at different ages and often will have a different prognosis as well with some seeming to get a more severe form of the disease than others.
19:33 DD: Okay. I just thought of a really bad pun. So if one size doesn't fit all, then in this disease becasue I think as practitioners, not being a cardiologist, but being an internist and seeing these guys, we tend to treat them all the same. So, do you see this being... I know this is a really hot term right now, which is personalized medicine, is this going to be something that's going to be personalized for dogs then or do you see that maybe happening?
20:03 DM: I do, I believe that and I hope that's the case and when I went out to speak to veterinarians in Kansas two weekends ago with at the Central Veterinary Conference and what I tell them is right now in 2018, we talk about there is one way to treat this disease but that I hope and maybe as soon as five years that the speaker in front of them is saying if you have a Miniature Poodle or this type of genetic makeup, you're going to choose these medications or you might choose this type of diet which is different from if you're working with the Yorkie, you're going to choose this so I think that is exactly right and I believe we will be much more effective that way if the profession is actually able to use this research that comes from the Mark Morris Jr. Award to personalize how they treat individual patients. Now, I know still we have to talk about what's very practical in veterinary medicine because not everybody is going to be able to do all levels of genetic tests on this dog and that but I think it is very practical for veterinarians to be able to look at the dog and understand that that is not the same as some other breeds and how that may alter their choice of therapy and lifestyle, things like diet, exercise, what sort of activities the owner chooses to do with that dog.
21:33 DD: Okay, did these results surprise you? Did you expect setting out that it would be more similar or did you with your experience say, I have this gut feeling these are different?
21:49 DM: Certainly, if you had asked me 10 years ago it would surprise me. As a profession we have tended to put these diseases in broad categories, this is all valve disease and even that this is probably the same as in human beings. And so it has surprised me a little bit that it is not the same and not the same across breeds but I think the more I think about it and anybody who's listening thinks about it biology is so different and clearly these dogs. We've bred them to look different and have different personalities and that's one of the things we love about them is there is this great variation and so it does make sense that even at a cardiac level there may be some small variance that make a big difference.
22:42 DD: Okay, so yeah, that's really cool. I think I was certainly taught it's one disease while with the maybe the Cavalier King Charles being the first one that might be a little different but it's spreading it even more, so how do you... You alluded to this a few minutes ago but if you could expand on how do you envision this, the research and the results changing how veterinarians in private practice, practice?
23:16 DM: Well, I think and some it if you will is absolutely education, getting them to the point because this is what we were all taught that this is not just a single disease and so understanding that you may tweak how you manage these patients a little bit differently. But I also... I really hope that one of the things I try to talk to them a lot about will be using this information for very early intervention that when someone comes to you with a puppy that we can begin to think about, based on what breed it is or even if it's a mix, if I know it's a part Cavalier and part Yorkie that those are breeds that have this inheritable heart disease and that even as a puppy I might begin to think about, "Am I going to treat this different, start talking to the owner about things to watch for, the age when it may be at risk."
24:16 DM: And then I hope in the not too distant future that they may consider even doing a genetic test. Cost of genetic tests these days is as low as $35, so you can take a few cells from the cheek and I hope that someday, in the not too distant future, from this study we actually have a genetic marker that they can test from, test for and if that dog has that genetic mutation that then they may say, "We should start this dog on a drug like enalapril, an ACE inhibitor even at a year of age because that might slow down the progression." So I want it and I believe it can have a very practical implication for general practitioners, for people even on more limited incomes who want to do the best thing for their dog but the key there I think will be really early recognition, by recognizing who that dog is and that they're at risk group and then beginning to intervene very early.
25:28 DD: Okay, so I know you have lots of projects that's my advantage sitting here with cats and dogs and genetics but once this project, this particular project is done what do you want to do next? Where do you think you're going to go next?
25:45 DM: Oh, I think where I really would like to see is studies that demonstrate that this early intervention makes a difference because that's not something that we as veterinarians do quite yet. We tend as we physicians we're often reactive, we wait for somebody to get sick whether that's a human or an animal and that's when we treat and so I really want to do some of the research with these genetic mutations that cause heart disease where we look at puppies and kittens that have risk mutations and study the impact of early intervention to them, whether that's starting a medication or again diet or other lifestyle things, to try to demonstrate how that made a difference in when they developed disease. Those are a little bit tricky studies to do because diseases like valve disease may not show up until five to eight years of age and so you have to be planning on doing this as a 10-year study and you have to have enough owners who say they're going to keep living in Raleigh North Carolina for 10 years and participate in this study.
27:03 DD: But I really think that's where health professions need to go, is this personalized medicine and personalized medicine in a proactive perspective, recognizing what your risks are and acting on those rather than waiting for disease. And so, I think in order for the veterinary profession to really grab onto that, we're going to have to have some good studies that show that that has made a difference. And so, that's what I would like to be part of next. And I'm trying to begin to do a little bit of that with some of my other studies, but as I said, it can take 10 years to get it done. So it's a long-term commitment, I'm afraid.
27:46 DD: Yeah. So well that is really cool. So I have one final question, which is really a personal question for you...
27:53 DM: Sure.
27:54 DD: Why did you ever... Why did you decide to become a vet, and why cardiology in particular? What fascinated you about that discipline?
28:05 DM: Oh, that's an excellent question. I was one of those people that decided very early on to be a veterinarian. Many people do, and I decided that my early recognition, remember in this was that I was seven years old, and somebody asked me what I wanted to do, and that was the answer I said, I was going to become a veterinarian, and I just never waffled off of that. I would guess probably similar for you, but maybe you don't want to spend the time on the podcast talking about it, but I think it's very common in veterinarians to make that decision early on. And then, to be honest, it often is, who influences you. So when I was a first year veterinary student at the University of Wisconsin, I took a summer job working for a veterinary cardiologist named Bruce Keene, who was also years ago, a Mark Morris Fellow, which was something they did in the early days, so he had also been funded by the Morris Animal Foundation to study heart disease in boxers, and I got interested in cardiology that way, but what... The influence that was bigger on me, even than cardiology, was the impact of research because that had not occurred to me. I had planned on becoming an equine practitioner actually, and going back to where I was from, to see cases but what I learned from Bruce Keene was this impact that as a practitioner, which is a very important job, I would see one patient at a time, and have an impact that way.
29:36 DM: And again, that's a very important thing to do, but as a researcher, you could have an impact on a whole breed of animals or a whole species of animals by discovering why they got a disease and developing a new vaccine or a new test, or a new drug and so you could have an even bigger impact. And so that early opportunity as a veterinary student to become involved in research and understanding how that could help a very large group of animals was really impactful for me and it stuck with me and then through that was also cardiology, but the research aspect was really important.
30:17 DD: Sounds cool. Yeah, I think I was the same. I was one of those people who picked being a vet pretty early and I don't even know why. I think it just popped out of my mouth and I agree, I think a lot of people decide on it pretty early, and then never really waver from it, so I can empathize there. I think a lot of us feel that way. And that was really cool, what she said. And I think also, I want to point out to our listeners that not only have you been a funded researcher, but you've also been a mentor to a lot of trainees, which is part of what Morris Animal Foundation's mission is to do, which is train our next group of scientists and you've... I think done everywhere from the summer students, right? All the way through fellowships, am I correct?
31:09 DM: Yes, thank you, and thanks for the support of the Morris Animal Foundation who funded Dr. Josh Stern, who's now at University of California. Davis is, as well as many other people along the line, but Morris Animal Foundation has been really visionary in recognizing the importance of training the next generation, and clearly trained my mentor, funded my mentor, who then and then funded me and that helped fund my mentee, and so it's been really a terrific decades-long relationship forming which I really am so thankful for.
31:45 DD: Right. So, well great, well thanks so much, Kate, for chatting with us today, and I think that's about all the questions I had for you, so I really appreciate it. And again, I can't say how much we really love Kate at the foundation and for all she's done for us. And good luck with finishing your award.
32:07 DM: Alright, well likewise, and thanks for everything, it was really a pleasure to join you today. This was a great experience, and thanks for the option to reach out and talk to everyone.
32:16 DD: Alright, thanks...
32:17 DM: Have a good day, thank you.
32:17 DD: Thanks again, Kate, you too...
32:19 DM: Bye now.
32:19 DD: Bye bye. That does it for this episode of Fresh Scoop. Once again, thanks to Dr. Kate Meurs, of North Carolina State College of Veterinary Medicine, for joining us and talking about mitral valve disease in dogs. We'll be back with another episode next month that we hope you'll find just as informative. The science of the animal health is ever changing and veterinarians need cutting-edge research information to give their patients the best possible care. That's why we're here. You can find us on iTunes, Spotify, Google Podcasts and Stitcher. To learn more about Morris Animal Foundation's work, visit morrisanimalfoundation.org. There, you'll see how we bridge science and resources to advance the health of animals. You can also follow us on Facebook, Twitter, and Instagram. I'm Dr. Kelly Diehl, and we'll talk soon.