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What does my dog's heart murmur mean? - Mitral Valve Disease❤️

Updated: Nov 9, 2022

Dogs can have heart murmurs for lots of different reasons. Some can be innocent and some can mean there is something going on with your dog's heart. In this blog post, we'll meet one of our veterinary nurses and her dog with mitral valve disease and our vet Naomi will explain what heart murmurs can mean and what we can do about them.

Mitral Valve Disease

Mitral valve disease is the most common cause of a heart murmur in dogs. This disease is a progressive, age-related condition that causes the valve between the left atrium and left ventricle to change shape allowing blood to flow backward into the left atrium, this backflow through the valve causes the murmur which can be heard with a stethoscope. In a healthy heart, the valves close completely when the heart pumps, stopping any backflow of blood.

Over time this backflow of blood causes stretching and enlargement of the left atrium and fluid accumulation in the lung fields (pulmonary oedema), the murmur also becomes louder, and dogs may also begin to develop signs associated with heart disease including tiredness and exercise intolerance, increased respiratory rate and effort, coughing and sometimes fainting or collapsing episodes. 

Affected animals are usually middle-aged to older dogs. It is most common in small to medium-sized breeds, especially the Cavalier King Charles Spaniel, dachshunds, terriers, chihuahuas, and miniature poodles. 

The easiest way to assess whether a heart murmur is causing a problem for your dog is by performing a heart scan (echocardiography) to assess the flow over the mitral valve and measure the size and shape of your dog's heart chambers. This information enables us to start medication as early as possible to slow the changes in the size of your dog's heart and improve their heart function.

Lucy and Blossom

This is my dog Blossom, she is an 8-year-old Bichon Frise. She has had multiple health problems since I rescued her 4 years ago; chronic ear infections, dry eye disease, skin disease, and hip dysplasia...just to name a few!

Blossom has also had a heart murmur since I have had her. It began as a grade 2 murmur, so the vets and I didn't worry too much about it. But at the beginning of last year, she started coughing. Mostly it was in the mornings or after waking up from a nap. At this point, I asked for a vet to examine her and we discovered her murmur had increased to a grade 4, this was more serious and so a heart scan and chest x-ray were required.

The results from her heart scan revealed she had Mitral Valve Disease (MVD) and the chest x-ray showed she had some fluid congestion in her lungs. And so her treatment began. She was put on two different tablets; one to improve her heart function and the other to stop fluid building up in her lungs. Blossom is a fussy dog so I was amazed when she ate her tablets like they were a treat and she started to look forward to medicine time!

Blossom gets tired very quickly and she does spend most of her day sleeping. She is taking her medication well, and having regular checkups with a vet to making sure her heart is still ticking on ok. I know that the MVD will eventually lead to heart failure and so I am appreciating every day I have with her. The best thing is knowing I have a whole team of vets available to speak to and calm my nerves when I am worried about her.

Annual health checks mean that every year your pet's heart is listened to and any problems are picked up early. If your pet has missed their annual health check then give us a call to book in.


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