When YOUR Heart Skips a Beat: Understanding Pet Heart Murmurs

By Andria Kennedy

The “M” Word

Everything was going just fine: you were standing in the veterinary office with your cat or dog (or even your ferret or bird), the examination was proceeding as usual, everyone was behaving themselves (at least for the most part), when the Veterinarian dropped those fateful words out of nowhere, “Fang has a heart murmur.”

Your entire world comes to a screeching halt.

Is Fang okay?

Is her heart okay?

Is she still breathing?

Are YOU still breathing?

Odds are that unless Fang was there for a suspected cardiac – or respiratory – emergency, she’s oblivious to your own impending heart attack, not to mention her current heart murmur. That won’t do much for your current heart rate of 300bpm, though. The sad fact is, unless it was a Cardiologist that uttered the words, your Veterinarian may not be able to provide you with a lot of answers or peace of mind. They likely will make a recommendation for you to see a Cardiologist, but, in the meantime, what are you going to do?

Sit and state at Fang every hour of the day, waiting for some clue that her heart is failing?

Fang isn’t really going to stand for that. So let’s see about a tiny peace of mind NOW.

What is a Murmur?

A heart murmur is abnormal blood flow through one of the valves in the heart. There are four valves in the heart, two on each side: the pulmonary and mitral on the left, and the aortic an tricuspid on the right. When these valves fail to close properly, blood continues to leak back and forth, creating turbulence that generates a “whooshing” sound. The greater the leak, the louder the sound; as the leak increases, a palpable thrill can also develop – a vibration felt in the skin over the location of the murmur.

Cardiologists use the strength of the murmur and the presence or absence of a thrill to Grade a heart murmur on a scale from I to VI:

  • I: the murmur is so soft it can only be heard directly over the affected valve (these can often be missed)
  • II: the murmur is still soft, but it radiates around the affected valve
  • III: the murmur radiates outward on the affected side of the chest
  • IV: the murmur radiates to both sides of the chest
  • V: the murmur can be heard on both sides of the chest, and a thrill can be palpated
  • VI: the murmur is loud enough to be heard without needing to place the stethoscope on the chest, and a thrill can be palpated

The important part to remember is that the Grade of heart murmur is ONLY used to describe the intensity of the murmur itself – how LOUD it is; the Grade of the murmur does NOT describe the severity of the heart disease itself. It is possible for a pet to have a Grade VI heart murmur with a stable heart condition, just as it is possible for a pet to have a Grade I heart murmur and a critical heart condition. If you can, try to ask your Veterinarian what Grade of heart murmur they hear at that initial visit. It won’t tell you what heart disease Fang has, but it will let you know where they fall on the scale (and it will help at your Cardiology visit).

Now vs. Later

Heart disease falls into two categories: congenital and acquired. Congenital conditions are those that pets are born with. Examples include patent ductus arteriosus (PDA), subaortic stenosis (SAS), and tricuspid valve dysplasia (TVD).

Most congenital conditions will be diagnosed while the pet is still young, and the majority of these conditions will worsen during the first year of life. Whether the pet will have a normal lifespan or not depends on the following:

  • How early the condition is diagnosed
  • How severe the condition is at diagnosis
  • Whether the defect is able to be repaired
  • Whether you move forward with any possible repairs (surgeries are often expensive – keep that in mind)

Acquired conditions are those that pets develop as they age. These conditions are typically diagnosed much later in life, and they continue to worsen as the pet ages.

Many pure-bred pets are predisposed to common acquired heart conditions, some of which can be tested for genetically. For example, Maine Coon, Sphinx, and Persian cats are predisposed to hypertrophic cardiomyopathy or HCM. Similarly, Doberman pinschers, Irish wolfhounds, and Great Danes are predisposed to dilated cardiomyopathy or DCM. If you have a pure-bred cat or dog, it’s important to research the genetic conditions inherent to that breed so you’re prepared for any surprises down the road. Ideally, try to do this before you bring your new friend home – you may decide that breed isn’t a good match for you.

For both congenital and acquired conditions, monitoring and medication (usually life-long) are to be expected, so you might want to consider either pet insurance or setting aside a savings account for your pet, just so you can be prepared – unless you can convince Fang to get a job.

“Broken” Hearts

The best source of information – and your peace of mind – is going to be a Cardiologist. Your Cardiologist will be able to not only confirm – or correct – your Veterinarian’s suspected murmur, but they’ll be able to provide you with an official diagnosis for Fang.

Be prepared for a lengthy Q&A session first because they need to have a clear picture for what’s going on with Fang, and, yes, every question really is important. They’ll check all of her vitals, including a blood pressure, which you may or may not have seen before. Fang will then be taken to a quiet, dark room to have the echocardiogram performed. No worries, though – it’s painless and unless Fang is extremely aggressive or stressed, no sedation is required (you can always ask for some for you if you’re still feeling anxious). All Fang has to do is lay on one side on a cushy, padded table, then lay on the other side – piece of cake! There will likely be some conductive gel involved, but they’ll make sure to wipe it off before she goes back to you (and it’ll be nice and warm, too, so that’s a bonus). They may want to take chest radiographs (x-rays), and they may ask to draw some lab work depending on what they see – it really is necessary. This will all take some time, so be prepared for a lengthy wait your first visit – bring reading material and maybe some soothing music for yourself; subsequent visits shouldn’t take as long.

The Cardiologist will then give you Fang’s diagnosis, as well as explain what it means and how they want to proceed with care. Don’t worry if you can’t think of every question at that time, because they’ll give you a phone number you can call when you get home, and they’ll be sure to follow up with you.

Breathe In…Breathe Out

Now, let’s recap:

  • Heart murmurs are the result of abnormal blood flow through a valve in the heart
  • Murmurs are Graded I-VI based on how loud they are and whether they have a thrill present
  • Grade of murmur does NOT correlate with severity of heart disease
  • Heart disease can be congenital or acquired
  • A Veterinary Cardiologist is the best source of information on the cardiac health of your pet

There’s no question that it’s frightening to hear that your pet has a heart condition, and it will probably make your own heart skip a couple of beats (hopefully, you don’t have a heart condition of your own!)

However, it’s not the end of the world and Cardiologists are out there to hold your hand and get you – and Fang! – through this. They genuinely love animals, and they know more about the heart than anyone. So take a deep breath, give Fang a big hug, and let’s go make that Cardiology appointment to get your answers!