Heart murmurs in dogs and what it means

12th Apr, 2022

Written by Nicola van Ass – Qualified Dog Trainer, Groomer and Feline Behaviourist

Most of us, at some point in our lives, have heard the words “heart murmur”. What is it? What does it do? How to we treat it?

In order to understand the above questions, we have to understand a little bit about the heart. When we listen to the beat of a healthy heart through a stethoscope, we hear a sound that we describe as “lub-dub”. Every beat has two parts, The “LUB” and the “DUB”. It’s a rhythmic, steady lub-dub, lub-dub, lub-dub. This sound is made from the normal opening and closing of the heart valves. A heart murmur is not the diagnosis, it’s a description of the sound we hear.

When there’s a problem with the blood flowing into the heart, what we call a turbulence of blood flow, the normal “lub-dub” sound is replaced with a “swoosh” noise. We then hear something like a “lub-swoosh”, “swoosh-dub” or “swoosh-swoosh”. This unnatural noise is called a heart murmur.

Around 60% of dogs over the age of five years old develop a heart murmur. Most murmurs are caused by cardiac disease (disease of the heart) or a problem outside the heart. Some are genetic and are passed on through the blood lines of the animal. Others are called Congenital Murmurs and are caused by heart diseases and develop in adult dogs.

We get six grades of heart murmurs, although the grade of the murmur doesn’t usually correlate with the severity of heart disease.

Grade I – barely audible murmur
Grade II – soft murmur
Grade III – intermediate murmurs – these are the murmurs which are usually related to the mechanics of blood circulation
Grade IV – loud murmur
Grade V – very loud murmur
Grade VI – not only is the murmur very loud, but it also has a vibration that’s strong enough to be felt through the animal’s chest wall.

If your vet, during a normal physical, listens to the heart and hears something that shouldn’t be there, they have a variety of options in order to confirm the type and grade of the murmur. They may call in a specialist who’ll do an ultrasound of the heart and is extremely important as it also can give a reason for what’s causing the murmur. Another option is a chest x-ray. This will not only let the vet see the chest cavity but also the lungs, to see if there’s any fluid there that comes from the heart. It can also allow the vet to measure the heart size.

When a heart murmur is discovered to have been caused by a disease of the heart, it’s known generally as congestive heart failure. This is a very serious condition and can cause death if not treated. Most dogs in heart failure will have a build-up of fluid in the lungs and may have a cough, difficulty breathing, or have no energy to exercise.

Some of the signs of congestive heart failure are:

Fainting
Coughing
Collapsing
Lethargy
Gagging
Trouble breathing
A change in appetite
Swelling in the abdomen
Muscle Loss

If your dog is coughing and hasn’t been diagnosed with kennel cough, allergies, or another explanation has been given, it could be that the heart has dilated and is putting pressure on the wind pipe or could be potential back flow of blood which causes fluid to build up in the lungs.

I know that reading the above information is scary when it comes to our fur babies. But there are numerous treatments available!

The treatment offered will depend on the grade and the underlying cause. A slight murmur in a puppy will likely need no treatment as they should grow out of it by the time they’re six months old. All that will happen is your vet will listen to your pup’s heart a few times a year to make sure everything’s going well.

When the murmur is caused by a heart disease, there are medications your vet will put your pet on in order to keep things under control. They’ll need to monitor the heart more regularly, and you may need to change their diet. There’s also an amazing app available called Cardalis, which your vet will help you register for. This enables you to monitor the way your pet breathes and will also send information directly to the vet so that they can keep an eye on your pet’s health from the comfort of your own home.

Remember, a murmur is NOT a death sentence for your pet! It just means you may have to do a little more to care for them in order for them to remain healthy.

If you have any concerns or worries about your pets, the first call you always make is to your vet. They’ve been put on this earth to help us keep our fur kids safe and healthy.

Testimonial Story

Talia my SoulMutt

Written by, and photographs supplied by, Nicola van Ass

Talia was a dog I thought would never exist. After having had to rehome a dog of my own as our garden was too small (she gratefully went to an amazing friend of mine), I was against getting a dog. After all, how can a dog trainer not be able to keep her own dog!

But one day, I saw a post from AACL, and the little dog of unknown age that was found on the side of the highway spoke to my soul. Shortly after that, Talia joined my family. That was seven years ago, and she’s about nine years old today.

In 2021 she started coughing, gagging after drinking water, and wasn’t her usual self. I took her to the vet, and he listened to her heart. A Grade V heart murmur! I was devastated. It was caused by congenital heart failure, and she was getting some fluid on her lungs. After tests and a confirmed diagnosis, my vet gave me the info about the Cardalis App. I was to monitor her breathing a few times each evening, especially when she was relaxed and sleeping. The data was forwarded to my vet with just one click.

After a week of monitoring, we came up with a treatment plan. Vetmedin for her heart and a diuretic for the fluid in her lungs. The difference was almost instant. She plays and barks and acts just like a dog who’s five and not nine years old! I know she may not live to the old age she would if she was healthy, but I know that because of the treatment plan, I have so many more years with her.

Having a heart murmur isn’t a death sentence. It’s something that generally can be managed, and I urge anyone to meet her and tell me she isn’t a perfect little angel! Talia is my SoulMutt, and even though this is going to be a long-term journey, she’s as happy as can be, and I love her more each and every day.

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