Hypertrophic Cardiomyopathy In Your Cat @ The Longevity Vet

Well, hey you guys! Welcome back to The Longevity Vet. I'm Dr. Kevin Toman Toman, and I'm glad you're here. Today we're going to take a deep dive into hypertrophic cardiomyopathy in our cats. Why? 3 reasons. First off, hypertrophic cardiomyopathy, or HCM as it's lovingly abbreviated, is the single most common type of cardiac disease that our kitties run into. Secondly, it's been uniformly fatal. In the 38 years that I've been in veterinary practice, up until now, we've just never had a drug that could stop or even slow the progression of HCM in our cats. Now we do. There's a new drug on the block called rapamycin, and we're going to talk much more about that in this video. The third reason I wanted to do this video is just simply because veterinary cardiologists are not spread equally through the United States. In fact, I would bet you that there are places where you and I could drive a day or two and never run across a veterinary cardiologist. And so, if you have an HCM cat and you live in Susitna, Alaska, or Skowhegan, Maine, or Wise River, Montana, this video is for you. So what is HCM? Well, it's a genetic disease, and I'm going to circle back to that in a moment, but it's a genetic disease that causes marked thickening of the chambers of the— excuse me, let me try that again— of the walls of the chambers of the heart., and in particular, it affects the left ventricle. So I took the liberty of copying a page out of an old textbook here, and on your left, you can see this is a normal cat heart. You can see how thin the walls of the heart are here. And then this is the representation of a cat with HCM, and you can see how markedly thickened the lower chambers of the heart, the walls of the ventricles are. And the significance of that is threefold. First off, as these ventricular walls thicken, logic would tell you that the volume of those chambers shrinks. I mean, the walls are increasing in size, chamber, and so the chamber has to decrease. And so the first thing you will see with HCM is that your cat's heart is not pumping as much blood per contraction as it normally would. That figure is called stroke volume, and so the first thing we see with HCM is decreased stroke volume, or the amount of blood that is pumped from the heart with each contraction. The second thing that this ventricular thickening does is it screws with the anatomy of the heart valves. These heart valves are very thin, almost paper-like structures, and they are responsible for keeping blood flowing from the heart out into the periphery. But if HCM affects them, then all of a sudden these heart valves become defective, creating that murmur that I spoke about— or let me try that again— that I will speak about in this video. And so not only does HCM reduce stroke volume, but it also makes every heartbeat less efficient by screwing with the heart valves. The third thing it does is that the thickening of the ventricular walls creates turbulence in the blood flow. Under normal circumstances, the blood flow from the ventricle ought to be like you and me, we're using a garden hose. But because of thickening of the heart, these— the blood vessels, excuse me, the blood in there just turns around, becomes much more turbulent. And what happens is That pisses off the platelets. And when platelets get pissed off, what's the first thing they do? They trigger a clotting cascade. And so these HCM kitties are very prone to forming blood clots in their left ventricle, which then pass through that defective valve down into the aorta, which is the big blood vessel that supplies the lower half of the body with blood. And they travel along until they come to the point where that aorta, that big thick aorta, divides into two smaller femoral arteries that supply each of the legs, and then those blood clots get stuck there. That's known as a saddle thrombus, and if you see a saddle thrombus in a kitty, you'll see three different things. First off, you'll see a kitty who's excruciatingly painful. This is just one of the most painful diseases that we'll run into. Secondly, you'll see a cat who can't use their hind legs. They simply drag them along, and unfortunately, the third thing you'll many times see is death because once a saddle thrombus has been in place for any period of time, veterinarians like me have a hell of a time trying to solve that. So, who gets HCM? Well, as I mentioned, it's a genetic disease, and so the poster children for HCM are typically Maine Coons and Sphynx cats. And in both of those cases, you can do a genetic test, a blood test, to determine whether these cats have the genes for HCM that will cause problems for them down the road. And so, as an aside, if you are thinking about getting a Sphynx or an H— or excuse me, a Maine Coon kitten, one of the first things you should do is to double-check that your breeder has done HCM blood tests on both the dam and the sire of your kitty, because if they both carry the HCM gene, the odds are high that your kitty will develop HCM over the longer term. So please avoid that heartbreak. If you can. Other breeds that are very commonly affected by HCM are Persians, the shorthair breeds, and Ragdolls. But let me be clear, any breed, any cat breed can develop HCM, so you're never completely safe. So how do we diagnose HCM? Well, honestly, most times at home, you will never notice that your cat has HCM because HCM can be a very slow-moving and progressive disease. So if your cat has early HCM, honestly, you probably won't see a single thing. But if your cat has more moderate, more severe disease, you will see the classical signs of heart failure develop. And by that, I mean a cough, moping around, not wanting to move very much, lowered appetite, and therefore some weight loss. And in really severe cases, you can sometimes see a bluish cast to your cat's gums instead of the nice healthy pink that we want. How do veterinarians diagnose HCM? Well, Honestly, probably 80 to 90% of the time, HCM is what you and I would call an incidental finding, where you go into your vet's for a physical exam and your vet looks at you and says, "Hmm, I've never heard a murmur in your cat before." And so the first thing the veterinarian will hear is almost always a heart murmur. And if that is the case, then as I mentioned before, HCM is the single most common reason for that heart murmur, and so the common recommendation is to have your cat go through an echocardiogram or an ultrasound study of the heart. That's the gold standard when it comes to diagnosing HCM because an echocardiogram allows us to actually look inside the heart and to measure wall thickness and to measure the velocity of blood leaving the heart and also to look for evidence of clots forming., and one of the first things that you will see if your kitty is trying to develop clots is kind of a turbulent— the turbulence creates a phenomenon known as smoke. And so if your echocardiogram comes back and the veterinarian mentions smoke in the left ventricle, then that's a sign that your kitty is trying to develop clots and should be started on a drug like clopidogrel, which we'll talk more about in just a couple of minutes here. So if a veterinarian like, like me, a general practitioner, diagnoses a kitty with HCM, there are a couple of other tests that you and I should pay close attention to running. First off is chest films, just simple chest x-rays, because those regular chest x-rays will allow us to look at the overall size of the heart, and it will also enable us to look for the signs of heart failure, which typically involve fluid accumulation within the lungs. We should also do some blood tests on your kitty, and the reason for that is that HCM can create kidney problems in particular as the HCM progresses, and so I typically recommend the use of a complete blood count, a chemistry panel, and a urinalysis with the goal of assessing your cat's overall health, but in particular, their kidney function. Another test, another blood test that's important for us is a thyroid test because hyperthyroidism is a common disease in kitties, and so, as an aside, what you would see with that is increased appetite and increased activity. Little cats on speed is what hyperthyroidism calls, but as a result of that increased metabolic rate, hyperthyroidism can put a tremendous workload on your cat's heart, so you always want to check thyroid function if your cat has been diagnosed with HCM. The final blood test that I routinely recommend is called ProBNP, although most folks just call it the BNP test. And the BNP measures the amount of stress that your kitty's heart muscle is under, and it gives you a numerical value. And so it's sometimes pretty expensive to go in for repeated echocardiograms to keep track of your kitty's HCM, and the proBNP blood values mimic the changes within that echocardiogram, and so it's a cheaper alternative for you to monitor your cat's progression through HCM is many times the BNP blood test. So So let's talk about Rapamycin for just a second. About 2 years ago, a veterinary company called Trivium came out with a study that showed that delayed-release Rapamycin tablets slowed the progression, or sometimes even stopped the progression, of HCM in about 2/3 of cats. Now, a couple of caveats: their study only involved 45 cats, so it wasn't very big, and they also limited study participants to subclinical HCM cats, not the, the cats in fulminant heart failure like I sometimes see in daily practice. But the flip side to that is this, and that is we have never, in my 38 years of veterinary practice, ever had a drug that I could look you in the eye and say slowed or stopped progression of HCM in a majority of cats. Now we do. The other thing that's pretty cool about rapamycin is that it has been proven in other species to benefit heart function, especially dogs, and it's widely used as a longevity drug because it reduces cancer risk and also it reduces inflammation. Rapamycin was also shown recently to improve geriatric hearing loss, which is important to a 64-year-old veterinarian like me, and also to reduce the progression of periodontal disease. Finally, and here's a, here's a major plus for us kitty owners, and that is that, excuse me, that rapamycin has been proven in other species to reduce the progression of chronic kidney disease, and it's actively being studied at Florida State and Ohio State University universities, the vet schools there, to see if Rapamycin can also benefit chronic kidney disease in our cats. So Rapamycin is certainly the very first drug that you should reach for if your cat has HCM. Now listen, I have a horse in this race because I sell Rapamycin with your veterinarian's prescription or after doing a concierge consult with you, but you can find Rapamycin in other places, and if your kitty is developing HCM, this is the very first drug that you should think about. Now, here's where we're going to talk about drug doses and the reason for using other drugs in HCM. And so you're going to see that I'm going to cheat. I'm going to look over to my left because this is a 20-minute video. I'm just a GP veterinarian. I'm not a YouTuber, and I want to give you some drug doses, and I want to be very specifically accurate to them. And so I apologize for this, but you are going to see me look down every once in a while. And so the first drug that many veterinarians place a kitty with HCM on is a drug called atenolol, A-T-E-N-O-L-O-L, and the reason for that is that atenolol reliably slows a kitty's heart rate and also reduces the kitty's blood pressure. And oh, that's one thing I should have mentioned. In addition to the blood tests that I spoke about for diagnosing HCM, The reality is that any HCM kitty should also have their blood pressure taken. Why? Because HCM can create hypertension or high blood pressure in your kitty, and if so, we need to treat that before the hypertension creates, um, blindness, creates stroke problems, or creates kidney disease. And so let me repeat that: any HCM kitty ought to have a blood pressure reading done every 3 to 6 months. All right, so back to atenolol. Here's the deal with atenolol: the, the primary benefit is that it slows a kitty's heart rate. Why is that important to us? Because it allows that defective ventricle to fill with more blood before the heart contracts, and so if your kitty's heart rate is too fast because of HCM, that left ventricle never has a chance to completely dilate and fill with blood, before it contracts, and so therefore your kitty's stroke volume will be decreased again. Atenolol will also typically reduce blood pressure by about 10 points, which can be a lifesaver for your kitty. And so here's where I'm going to look down— the, the atenolol dosing. We typically start at 6.25 milligrams per cat, not per kilo, 6.25 milligrams given to a cat twice daily, and if you don't see the response that you like within a 10 to 14 day period, you can increase that by 6.25 milligram increments. So usually go from 6.25 milligrams twice daily to 12.5 in the morning, 6.25 at night, and then 12.5, 12.5, etc. And you work with that drug until your, your cat's blood pressure and/or heart rate return to normal levels.. The next drug that we should talk about is a drug called clopidogrel or Plavix. And the reason for using that is that it stops platelets from being activated and aggregating. And so basically clopidogrel is the classical clot preventer. If you want, if you're concerned about your kitties developing a saddle thrombus, or if your echocardiogram comes back and mentions smoke in the ventricle, The reality is every cat ought to be started on clopidogrel to prevent the heartache of a saddle thrombus from developing. The clopidogrel dose is typically 37.5 to 75 milligrams a cat, given as a loading dose, and then after the first day or two on that high dose, we typically try to reduce them to 18.75 milligrams per cat, given once daily. Now, in the old days, we used to use baby aspirin in an effort to try and reduce clotting. And some veterinarians still recommend it, but I will tell you very personally that I have created a lot of stomach ulcers, a lot of cats who puke up blood or develop bloody diarrhea by my starting cats on baby aspirin, and so personally I would avoid that if at all possible. However, if you do choose to use baby aspirin or can't, or the clopidogrel is difficult for you to administer, the typical baby aspirin dose is 5 to 10 milligrams per cat orally every 2 to 3 days. And so let me repeat that: 5 to 10 milligrams per cat orally every 2 to 3 days. And so that is just a fragment of the typical 81-milligram strength aspirin, baby aspirin, that you and I could buy at a drugstore. Moving right along, the next drug that we should think about is Pimobendan, or Vet Medan, which is the trade name for Pimobendan. And the reason that we should think about that is that pimobendan is known to increase the strength of every heart contraction. So we talked about how atenolol can allow that ventricle to more fill— to fill more fully. Let me try that again. And pimobendan simply helps that heart to go ahead and contract more fully and therefore expel more blood. So it also will increase stroke volume for you. And the Pimobendan is— the Pimobendan dosing is 1.25 milligrams per cat given twice daily. So you typically end up splitting a 2.5 milligram or 5 milligram tablet down into halves or quarters respectively. All right, moving on through the list of medications for the typical kitty with HCM. Next one is amlodipine, which is strictly a blood pressure medication. Remember I told you that every cat with HCM ought to have their blood pressure taken, and if their blood pressure is high, if they are hypertensive, which typically means a blood pressure over about 140 millimeters for systolic, then we typically start these kitties on amlodipine, and the dosing there starts at 0.625 milligrams per cat. Let me repeat that: 0.625 milligrams per cat. We give that dose for 2 to 3 weeks, and then we can double it from there if we don't see the response that we'd like, but you typically don't want to give a kitty any more than about 2.5 milligrams per cat. Next drug in line is a drug called benazepril, which is an ACE inhibitor, and it's another drug that we use to reduce blood pressure and to help kidney function. And so I mentioned before that HCM has a tendency to screw with our kitty's kidney function, and one of the first things we'll see if your kidneys are being damaged by HCM is protein loss into the urine. And so if your vet— excuse me, if your kitty's urinalysis ever comes back indicating protein loss into the urine, we typically reach for benazepril as a drug to go ahead and both reduce blood pressure and help minimize the loss of protein into your kitty's urine. All right, finally, we should talk about furosemide, which is a rescue drug. It's a drug called diuretic, so it simply sucks fluid out of where it's not supposed to accumulate. How does that help us with a case of HCM? If your kitty's heart is failing, the first thing you're going to see is fluid accumulation within their lungs, and furosemide is a rescue drug that can help suck the fluid out of your kitty's lungs, deposit it back into the bloodstream, and then have— develop— let me try that again. Furosemide will suck fluid out of your kitty's lungs back into the bloodstream, or it can be peed out by a normally functioning set of kidneys. Typical dosing for furosemide is 2.2 to 5.5 milligrams per kilo, given orally once to twice daily. Let me repeat that: the furosemide dosing is 2.2 to 5.5 milligrams per kilo body weight, given orally once to twice daily. So other things that you can do, uh, is to— you consider at home is to monitor your kitty's respiratory rate. There are actually a couple of apps that enable you to do that more accurately. One is called Cardalis, C-A-R-D-A-L-I-S, and that's available for both Apple and Android phones. The other one is the Pet Breath Counter app, and it too is available on both platforms. Some folks go to the point where they have oxygen available for their kitties at home. By the time you and I need that, I would suggest to you that we have bigger fish to fry., and then there are times when if your kitty goes into the vet for congestive heart failure and their x-rays, their ultrasound exam shows a lot of fluid accumulation in your kitty's chest, they can actually use a large bore needle to suck fluid back out of your kitty's chest. That's a process called thoracocentesis. T-H-O-R-A-C-O, thoraco, C-E-N-T-E-S, IS, and that again is a situation— that's a medical procedure that is reserved for these kitties in fulminant heart failure. So as an aside, we should talk a little bit about delivering medications to your cat, because I mean, hell, I've given you a list of 5 or 6 medications, and that can be kind of a pain in the ass to give to many cats. I speak for myself, some cats are virtually impossible for me to pill, so you should understand that your veterinarian can work with a formulating pharmacy to develop topical or transdermal medications. They come in kind of a thick syringe and basically just click out your dose and rub it into the back, typically any hairless area on your cat. But the one area that your cat cannot reach with their tongue is the hairless area on the back of their ears. And so if you, like me, have difficulty pilling a cat repeatedly, you might want to consider the transdermal medication route. It's a little bit more expensive, but the flip side to it is it makes your life a lot easier. All right, and so where are we? The other thing that we should talk about a little bit is diets for kitties. And, you know, we talked about the difficulty of getting medications into a cat, and listen, I know very clearly that kitties are creatures of habit when it comes to their diet, but just understand that many of the over-the-counter diets are very high in sodium. Cats like the taste of salt, just like you and I do, and salt is not our friend in our HCM cats because it'll— extra salt in the diet will increase blood pressure. And so Tufts University actually has an online list of cat diets that are specifically designed for kitties with HCM. So again, you can go to the Tufts University HCM diet, and you should be able to track that down on any browser. Okay, so where do we go from here? I guess the other thing that we should talk about is what veterinary care should look like for a kitty that has been diagnosed with HCM. And I typically recommend comprehensive dental care, at least on an annual basis. And this is important because if your cat develops a lot of oral bacteria, that bacteria, the oral bacteria, have a definite tendency to settle out in the heart valves and further screw with their function. And so whatever you and I can do to reduce oral bacterial counts will be a huge plus for you. Now, I want you to make— I want to make one thing clear, and that is that the best way to treat your kitty's dental health is to anesthetize them so that your veterinarian can take x-rays of every tooth in their body and either extract or medicate any tooth that needs help. And that is both an expense and there's a little bit of an anesthetic risk, but I want to remind you that if your cat has a dental abscess, they are in daily pain. They hurt every day of their life, and that's the last thing a kitty with HCM needs, is to add more stress to their life. The other reason I recommend anesthetic dentals early in the game is because one of the things we know is that HCM typically will progress and so you— as a kitty goes through HCM, their anesthetic risk is going to increase, so let's get as much of the work done early in the game as we can. So I also recommend echo rechecks every 6 to 12 months by a veterinary specialist, again, a cardiologist or radiologist, and this is an expense. You can minimize that expense by maybe using the BMP blood test to follow your kitty's progression, and that should be done every 3 to 6 months as well. And then I do recommend following a kitty's lab work on an annual basis with the complete blood count, the chemistry panel, and the urinalysis that we talked about, just to keep track of organ function over the rest of the kitty. All right, so what's the prognosis here? If your cat has very mild hypertrophic cardiomyopathy, they may live a long and happy life, but the worse that hypertrophic cardiomyopathy gets, the shorter their lifespan will be, to the point where some cats, by the time they're diagnosed, have just months to live. So the hope is that the rapamycin that I've spoken about can extend their lifespan and increase their quality of life. The final point that I'm going to make is this, and that is that we are all in this together. My name is Dr. Kevin Toman. I run a website called HelpingPetsLiveLonger.com. I also have a red website called www.rapamycinforcats.com, and here's the moral to the story: if I can help you, I will. So if you have questions about your HCM kitty, please email me. My email is found all over those websites, and so I'm not all that difficult to get in touch with, and I will help you if I can. All right, you guys, well, thank you very much for your patience and listening to this video. If you have any questions, any comments, please get back in touch with me, and Otherwise, hug your kitty today. Have a great day. Bye now.