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Heart Murmurs in Older Dogs: An Owner’s Guide

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inspection of heart murmurs with older dog

So, your vet has just told you that your elderly dog has a heart murmur. Your first reaction might be to panic, concerned that your dog may have a heart attack any moment. Or your dog may have had a low-grade heart murmur for some time but recently it has become worse. There are many possible causes of murmurs, some are more of a cause for concern than others, but it’s never a bad idea to investigate a heart murmur in an older dog.

What are Heart Murmurs?

A heart murmur simply refers to the presence of abnormal sound produced by the heart, heard when listening with a stethoscope. These extra sounds come from turbulent blood flow within the chambers of the heart and usually appear and disappear between the normal beating sounds of the heart. A murmur can be high-pitched, low-pitched, long or short, or can even be continuous/constant.

The presence of a heart murmur doesn’t always indicate disease; some low-grade heart murmurs can be innocent such as physiological murmurs which can come and go with changes in heart rate – although these kinds of murmurs are more common in younger dogs.

However, many heart murmurs do indicate a defect or disease within the heart which can eventually lead to heart failure – these are caused by a structural abnormality within the heart that may affect the valves or muscles of the heart.

Murmurs are often graded on a scale of 1 to 6: a grade 1 murmur is very quiet and may only be heard intermittently. A grade 6 murmur is very loud and can even be felt when placing a head on the chest.

What are Symptoms of Heart Murmurs with Older Dogs?

A heart murmur is a symptom in of itself, however a murmur may be accompanied by other symptoms if your dog is suffering from heart disease. Other symptoms of heart disease include:

  • Lethargy
  • Exercise intolerance
  • Coughing
  • Breathing difficulties/gasping for air
  • Fainting
  • Reduced appetite
  • Swollen belly

If your dog is displaying any of these symptoms then they may be in heart failure. Symptoms can gradually develop over a period of weeks or months or can occur acutely. These symptoms and the murmur should be investigated as soon as possible.

What’s the Life Expectancy of an Old Dog with Heart Murmurs?

It can be very scary for owners to hear that their old dogs are experiencing heart murmurs. Besides discussing treatment options, owners naturally also want to know if heart murmurs can negatively impact their dog’s life expectancy.

The good news is that many old dogs that have been diagnosed with heart murmurs can still live a long and happy life. But it depends on the type of murmur.

“Innocent” murmurs may have little to no impact on your dog’s health. However, heart murmurs can also be caused by more serious heart issues which could impact your dog’s life expectancy. Read the next section to learn more about the primary causes of heart murmurs.

What are the Primary Causes of Heart Murmurs with Older Dogs?

There are many possible causes of heart murmurs in dogs, some of which are more common in small breed dogs and others are more often seen in larger breeds.

  • Degenerative mitral valve disease, or DMVD, is the most common cause of a murmur and heart disease in older dogs. DMVD is also more common in smaller breed dogs, and some breeds such as the Cavalier King Charles Spaniel are highly predisposed. It occurs due to an insufficiency of one of the valves in the heart, known as the mitral valve, which controls the flow of blood between the left atrium and left ventricle.

    When blood passes from the left atrium to the left ventricle, the mitral valve should close to prevent blood flowing backwards in the wrong direction. However, in DMVD this valve ‘leaks’ allowing blood to flow backwards, thus creating turbulence – this is known as valve regurgitation and it is this backwards movement of blood that produces a ‘whooshing’ sound known as a murmur. Overtime, this blood flowing the wrong way puts extra strain on the heart as it has to beat harder and faster to deliver the same amount of nutrients and oxygen to the body; the end stage of DMVD is blood backing up in the lungs and leaking out as fluid – known as congestive heart failure.
  • Dilated Cardiomyopathy, or DCM, is another common cause of a heart murmur in dogs, which primarily affects medium to large breed dogs such as Boxers, Great Danes, and Cocker Spaniels. A degeneration of the heart muscle and increased volume of blood within the heart lead to dilation of the left ventricle wall and stretching of the cardiac muscle, leading to a larger and weaker heart.

    Over time blood backs up into the lungs as the heart is inefficient at moving blood around the body, this can lead to the leakage of fluid from small blood vessels into the airspaces resulting in congestive heart failure. An enlarged heart also leads to insufficiency in the heart valves, and over time valves can regurgitate like in the case of DMVD. The turbulence of blood created due to DCM results in a heart murmur.

How to Diagnose the Cause of a Heart Murmurs

Diagnosis of the cause of a heart murmur is done through a combination of history, clinical examination, and further investigations such as echocardiography and X-rays.

veterinarian inspecting dog's heart

History: Providing a detailed history to your vet will help them greatly in ascertaining what the cause of your dog’s symptoms might be. Here is a list of common questions your vet may ask to help you prepare:

  • What symptoms have you noticed?
  • When did you first notice these symptoms and do they appear to be getting worse?
  • Are there certain situations or positions that your dog seems to suffer more in?
  • Does your dog seem more lethargic or do they get tired more easily during exercise?
  • Have you noticed any coughing or breathing difficulties?

Physical examination: Your vet will then perform a thorough clinical examination of your dog, paying close attention the color of your dog’s gums, their pulses and of course they will listen for any abnormal heart or chest sounds.

Some dogs in heart failure may have poor blood supply to their extremities; checking the color of their mucous membranes and gums will help determine this. Many dogs with heart disease will also have pulse deficits or weaker pulses as the heart is struggling to push blood to the extremities.

Auscultation is the name given to listening to your dog with a stethoscope. Your vet will listen to the heart for any murmurs and will check your dogs heart rate and rhythm. They will also listen to your dog’s chest to listen for any sounds such as wheezing or crackling which could indicate fluid buildup within the lungs.

Echocardiography: The fancy name given to visualizing your dogs heart with an ultrasound scanner, a vet can get vital information about the function of your dog’s heart this way. A vet can measure the thickness of the muscles of the heart, the size of the chambers of the heart and can observe the movement of the valves.

The efficiency of your dog’s heart muscles when they contract can also be measured and any valve regurgitation can even be identified through a technique called color doppler. This is the gold standard for diagnosing heart disease in dogs but not all veterinary clinics have the capabilities to perform an echocardiogram so referral may be required.


WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]


X-ray: Required for diagnosing congestive heart failure, chest X-rays can be taken to look for any signs of fluid building up within the lungs. The overall size and shape of the heart can also be observed. This is another vital part of the diagnosis process and often goes hand in hand with the echocardiogram.

Can my Dog’s Heart Disease be Treated?

Depending on the type of heart disease present and the severity, there are many medications available to help manage heart disease in dogs. As with many diseases, heart conditions can worsen over time and although these drugs can’t reverse the disease process, they aim to slow the progress and minimize the symptoms so that your dog can live a normal and happy life.

Regular checkups, scans and X-rays are recommended to ensure your dog is always on the most appropriate medication and correct doses.

As with any disease, the sooner a diagnosis is made and treatment started, the better the prognosis so be sure to get your dog checked by the vet at the first sign of symptoms.

What Can the Owner do to Help?

In the case of heart disease, there is no substitute for proper medication. However, there are some things an owner can do to help.

Don’t overexercise your dog, listen to them if they are telling you they’ve had enough or want to turn around on a walk. A dog with heart disease will get tired much faster than a healthy dog and overworking them will put excessive strain on their heart. Similarly, be sure to keep them cool in hot weather, if there are any signs of congestive heart failure, warm weather can exacerbate the problem by making their lungs work harder.

Some supplements such as vitamin B, carnitine and taurine may help a dog with heart disease as well as antioxidants such as vitamin E. Be sure to ask your vets advice before starting a supplement.

As you can see, the key to caring for a dog with a heart murmur is in the diagnosis. First you must find out if the murmur is present because of disease. With thorough investigations and the correct medication, a dog with a heart murmur can live a relatively normal and happy life.

Related Posts:

Old Dog’s Heart Problems.

Author

  • Alex Crow is an RCVS accredited Veterinary surgeon with special interests in neurology and soft tissue surgery. Dr Crow is currently practicing at Buttercross Veterinary Center. He earned his degree in veterinary medicine from the Royal Veterinary College (one of the top 3 vet schools in the world). Outside of work Alex enjoys keeping fit, travelling and painting.

Disclaimer: The information presented on this website is not a substitute for veterinary advice, diagnosis or treatment. We recommend taking your pet to the veterinarian for a full medical exam. Do not give supplements or medication without first consulting with your veterinarian first.

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