Getting to the Heart of the Matter – Heart murmurs in dogs

February being the month of luurve I thought I would write about matters of the heart. The actual heart. Sorry if anyone got excited there!

Whenever you take your dog to the vet, your vet will listen to their heart and chest. They are checking to make sure the heart beat is strong, regular and that there are no murmurs. A heart murmur occurs when the clear drum beat of the heart (often described as ‘lub dub’) has a swooshing sound. This is caused by the blood not being pushed cleanly through the different chambers of the heart, most often escaping through leaky valves back the way it came. It is one of the commonest signs of heart disease and I am going to concentrate on them in this article.

The breed we see most often with heart murmurs is the gorgeous Cavalier King Charles Spaniel. They often develop them fairly early in life, between 4 and 6 years old is average, but don’t usually develop associated heart failure for at least a couple of years. However, they can occur in any dog and are occasionally heard in puppies (but most will grow out of them)

Heart murmurs are graded from 1-6, with 1 being the quietest and 6 being so loud the normal beating of the heart is drowned out completely. In general the louder the murmur, the worse the leaking of the valves and as the disease progresses the murmurs will get louder. Every time your vet checks your dog they will record the degree of murmur, which allows them to track its progress. They will also be listening to the pattern of the murmur and whereabouts on the heart it is loudest. Often there are no outward signs of a problem, which is why regular veterinary check-ups are so important.

It is very worrying when your dog is diagnosed with a heart murmur and you can feel quite helpless. However, although we cannot cure your pet’s problem there is a huge amount both we as vets, and you as an owner, can do to help them. The first thing to determine is whether they are in actual heart failure and this is a really important point. Just because a dog has a heart murmur it does NOT mean they are in heart failure! It does mean, however, that thire heart is inefficient and has to work harder than a normal organ to do the same job. This puts it under more pressure and essentially means it wears out more quickly.

When a heart murmur is diagnosed, it can be helpful to perform some extra tests to determine how the heart is coping and what exactly is causing the sound. Techniques include ultrasound scanning (although some vets may need to refer you to a specialist for this), using x-rays to measure the size and shape of the heart and taking your dog’s blood pressure. It can be very useful to repeat these regularly (once or twice a year) to monitor the progress of the condition.

There are also things you can do at home. I advise my clients to take their pets heart rate at least once a week when they are relaxed, so any increases (which can indicate a worsening of the disease) are be picked up quickly. I also advise regularly timing a short walk they do often. This allows them to pick up on the very subtle slowing down that will occur early in the disease. Believe it or not dogs are far more naturally athletic and fit than us humans (even fat little Cavies!) and although, like people, they will eventually become breathless & find exercise more challenging, they can hide these effects of heart failure for some time. Other symptoms can include a soft wet cough, collapsing or even going blue or pale at the gums. However, these usually occur only when the heart is in advanced failure and treatment will be more difficult.

Before heart failure develops the best thing you can do for your pet is ensure they stay slim. Being over-weight makes it much harder for the heart to function well. However, once it occurs, the sooner treatment is started the better, which is why looking for the more subtle signs of the problem is so important. The good news is there are many different medications that can help your pet, which will very significantly increase their length and quality of life.

So, if your vet finds a heart murmur in your dog, don’t panic! Keep them in tip top condition, be vigilant for the signs of heart failure and once they occur ensure they start on medication quickly. With this your best friend is likely to be with you for some time yet, which will keep both your hearts from breaking!

Cat Henstridge BVSc MRCVS – Read more of her blogs at


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