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What is a heart murmur?

Does your dog or cat have a heart murmur?

What is a heart murmur?

A heart murmur is an abnormal sound in your pet’s heart, heard when a stethoscope is used to listen to the chest. A murmur indicates turbulent or abnormal blood flow in the heart. This can be caused by a problem with one of the heart valves being either too leaky or too narrow (stenotic); or by a congenital defect, for example, a hole in the heart or a PDA shunt. Occasionally murmurs may sometimes also be heard where no heart disease is present, for example in very anaemic animals, or an ‘innocent’ murmur in a young puppy.

Usually a murmur is one of the first signs that your pet has heart disease, and may be heard before any other symptoms are apparent.

What diseases cause murmurs in pets?

There are many diseases which can cause a murmur. The most common one in dogs is myxomatous mitral valve disease (MMVD), but other causes include dilated cardiomyopathy (DCM), aortic and pulmonic stenosis, patent ductus arteriosus (PDA), and ventricular and atrial septal defects (holes in the heart).

The most common cause in cats is hypertrophic cardiomyopathy (HCM), although not all cats with HCM have a murmur. Other causes include DCM, congenital tricuspid and mitral valve disease, and restrictive and unclassified cardiomyopathies.

Is my pet’s murmur serious?

While a murmur indicates that there may be a problem with the heart, it doesn’t tell you the cause of the heart disease, or how serious it is.

It may be the first symptom of a potentially serious problem. Therefore, it is important to do further testing to determine what’s going on.

If your pet is showing additional signs of heart disease, such as changes in their breathing, decreased energy levels, or fainting, it is very important to investigate their problems without delay.

What tests are recommended?

The gold standard test to check a murmur is echocardiography, which may also be called an ‘echo’ or a ‘heart scan’. This is where an ultrasound probe is placed on the chest and used to look at the heart walls, valves, and blood flow patterns within the heart.

Echo is the only way to determine the exact cause of your pet’s murmur. It can help to assess the severity of your pet’s heart disease and whether they need treatment or not. It can also tell us about response to treatment and your pet’s long-term prognosis.

As it simply involves placing a probe against the skin, it is non-invasive and non-painful. Most pets usually do not need any form of sedation for it, unless they are very nervous.

Your vet may also recommend radiography of the chest (chest x-ray). This is used to assess the lungs for airway disease, to assess overall heart size and shape, and to look for fluid on or in the chest. Sedation may be necessary for this test; your vet can advise you on this.

Can my pet’s murmur be treated?

After the cause and stage of heart disease is determined, your vet can advise you whether your pet needs treatment.

In some cases, your vet may advise that no treatment is needed; we may even find that your pet is on a medication that is not necessary.

In other cases, various heart medications may be prescribed to address your pet’s heart disease, and these will be tailored to your pet’s condition.

Early treatment can make a big difference to the progression of your pet’s heart disease and in some cases can even add years to their lives.

Compared to in the past, modern heart medications are very safe and effective. Appropriate treatment of heart disease can delay the onset of heart failure, and can mean a longer and happier life for your pet.

Southview Veterinary Hospital offers a dedicated small animal cardiology service run by Deirdre Sheehan MVB GPCert(Cardio). We can cater for both routine appointments and emergencies and are happy to take referrals. Our services include full Doppler echocardiography – using state of the art GE Logiq ultrasound – as well as ECG, digital radiography, and Holter monitoring.