A heart murmur is an abnormal sound in your pet's heart, heard when a stethoscope is used to listen to the heartbeat. A murmur indicates abnormal, or turbulent, 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, e.g. a hole in the heart or a PDA shunt; or sometimes by physiological conditions e.g. in young puppies or very anaemic animals.
A murmur can be one of the first signs that your pet has heart disease, and may be heard before any other symptoms are apparent.
There are many diseases which can cause a murmur. The most common one in dogs is 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 heart disease that causes murmurs in cats is hypertrophic cardiomyopathy (HCM), although not all cats with HCM have a murmur. Other causes in cats include DCM, congenital tricuspid and mitral valve disease, and restrictive and unclassified cardiomyopathies.
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, changes in their energy levels, or fainting - it is very important to investigate their problems without delay.
The gold standard test for investigating a heart murmur is echocardiography. This may also be called an 'echo' or a 'heart scan'. This is where ultrasound is used to look at the internal heart structures and movement of the valves. Doppler echo can directly show the movement of blood within the heart chambers and great vessels, and helps to assess all aspects of heart function.
Echo is the only way to determine the exact cause of your pet's murmur. It also helps us to assess the severity of heart disease, what the best treatments will be, and your pet’s prognosis. We use it to monitor your pet’s response to treatment.
Echo is a completely non-invasive and safe test, and most pets do not need any sedation for it.
Your vet may also recommend radiography of the chest (chest x-ray). This is useful to assess the lungs, the blood vessels in the chest, and the overall size and position of the heart. Radiography can help determine whether your pet is in congestive heart failure or not. Mild sedation may be necessary for this test; your vet can advise.
After the cause and severity 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.
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.
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