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Heart Murmur in Cat
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An_220726 posted:
We recently to our cat to the vet and were told that he has a heart murmur and on a sclae from 1-6 its about a 3. His past owners were never told and we are checking old vet records but we are not sure if this is a new thing or if he was born with it. Is there anything we should be concerned about? Is there anything we can do to make the situation better aside from surgery?

Thank you
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shellybeau responded:
Hello Anon_21243,
My dachshund was diagnosed with a level 3 heart disease. I was told his heart was enlarged and his murmur was getting worse. Because my poor dog (14 years old) was suffering so much from the harsh medication he was on, I was seriously going to put him down one morning due to lack of enjoyment of life. My friend talked me into a second opinion. Not only did Oscar NOT have stage three heart failure, he didn't EVEN have a heart murmur. While it's hard to believe a simple heart murmur can be misdiagnosed, it can and does happen. My new vet took him off of Lasix, Vetmedin, steroids, as well as other toxic non necessary medication. I am so glad I got a second opinion. I go to a vet that has 5 doctors that openly consult with each other. My old vet was working by himself. Please get a second opinion; the new vets still tell me how surprised they are of the good condition of Oscar's vital organs after being on all that poison. Good luck to you and your cat!
 
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srstephanie responded:
How old is your cat? If there were past owners, then I suspect he is more than 6 months old. Young kittens can have benign developmental murmurs that usually go away by 6 months. Murmurs heard after 6 months should usually be checked out.

While there can be other causes of a heart murmur, the most common heart problem in cats by far is HCM "Hypertrophic Cardiomyopathy". HCM causes a thickening of the left ventricle of the heart and is a genetic disease. There are secondary forms of it caused by hyperthyroidism or hypertension which is common in older cats ... so, if your cat is a senior, then you should first rule out hyperthyroidism (via a blood test) and high blood pressure.

Primary HCM is a very frustrating disease. It may not show up in a cat until 7-8 years old, or may be seen in some as early as 6-8 months of age (Ragdolls are known for early onset HCM). It is not curable and is progressive ... but the course of the disease is not predictable. In some cats it progresses quickly, in others it remains stable for many years and may never be a factor in their health ... and others may have an early rapid progression and then stabilize for a number of years. It is a scary disease because it is unpredictable but many cats live for many years with it.

One of the common symptoms of HCM is a heart murmur ... though about half of cats with HCM do not have a heart murmur. The murmur is caused as the heart muscle thickens and interferes with the proper working of the mitral valve, causing a back-flow of blood that causes an audible murmur. This is called SAM (systolic anterior motion of the mitral valve).

One of the characteristics of murmurs in HCM is that they are "dynamic" murmurs. That means that the become louder (a higher grade on the 6 point scale) when the cat is stressed and are softer or non-existent when the cat is fully relaxed. So, a cat can have a higher grade murmur at the vets where he is scared and stressed, but have a lower grade or no murmur at home when relaxed.

Since there are other things that can cause a heart murmur, the only way to have a definitive diagnosis is by having an ultrasound of the heart (aka echocardiogram). It can be very expensive because it needs to be done by a specialist ... ideally a Board Certified Cardiologist or perhaps Internist ... because it requires great skill to interpret the ultrasound.

Last summer I had the privilege to attend the annual meeting of the American College of Veterinary Internal Medicine (ACVIM) which includes the Board Certified Cardiologists ... and the world's foremost expert on feline HCM, Dr Mark Kittleson, gave a 4 hour course on it. After years of research, primarily with his Maine Coon colony, he really doesn't believe there is any medication that will slow the progression of the disease prior to congestive heart failure (at which point he does think a diuretic like Furosemide, aka Lasix, is beneficial). But many vets, including Cardiologists, give a beta blocker like Atenolol, which slows the heart rate and can lessen the SAM (i.e. heart murmur). However, it generally only helps during physical exertion and cats tend to sleep most of the time.

Many cats with HCM have no noticeable symptoms. Others may be more quiet and after physical exertion may cough or pant/breathe through their mouth. Congestive heart failure can cause fluid around the lungs that inhibits breathing. Getting it drained and giving Lasix can help at that point. Another scary symptom of HCM can be the throwing of a blood clot from the heart. They usually settle where the artery splits to go down the back legs, resulting in hind paralysis. If an ultrasound shows clots or an enlarged left atrium a vet may try some anti-coagulation medicine, though many don't think it helps.

I'm not a vet and don't want to jump to conclusions on an HCM diagnosis, but it is something to get checked via ultrasound in a cat older than 6 months old with a heart murmur.

Good luck and I hope it is nothing.
 
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AMERICAN VETERINARY MEDICAL ASSOCIATION
Drew Weigner, DVM, ABVP responded:
Heart murmurs indicate turbulence as the blood flows through the heart. There are many things that can cause a murmur by increasing turbulence that have nothing to do with heart disease such as fevers, anemia, high blood pressure, thyroid disease, etc. A thorough physical exam and lab tests should tell you if these situations exist. If everything turns out normal, it's likely your cat actually has heart disease. This is confirmed by echocardiography (heart ultrasound.)

Some cats are born with heart murmurs, just like some puppies and children. It's less likely the murmur is significant in these cases (but still possible.) It's more likely to indicate a problem in a cat that never had a murmur and developed one later on.

It's also very important to find out what's going on now. If your cat turns out to have heart disease but has no symptoms, it's fairly easy to treat and the prognosis is much better than if symptoms already exist (lethargy, weakness, difficulty breathing.) Once symptoms start, your cat will be in heart failure. While this can be treated and most cats improve dramatically, few cats live longer than several months after diagnosis, so you can see the prognosis is much, much better in cats diagnosed early. Incidentally, treatment usually means medications. Surgery is rarely performed to treat heart murmurs, except in cases of heart defects present at birth.

Drew Weigner, DVM, ABVP
The Cat Doctor
Board Certified in Feline Practice


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