Heart health is an essential aspect of your pet’s overall well-being, and heart murmurs are one of the most commonly encountered cardiac conditions in veterinary medicine.
So, we’ve asked our vets to explain just what heart murmurs are, what causes them, and how to treat or manage heart murmurs, should they impact your dog or cat.
Let’s start at the beginning…
What is a Heart Murmur?
A heart murmur is an abnormal sound heard when a veterinarian listens to your pet’s heart using a stethoscope.
Instead of the usual ‘lub-dub’ heartbeat, a murmur produces a ‘whoosh’ sound caused by turbulent blood flow through the heart.
Murmurs are not diseases themselves but rather a sign of a potential underlying issue that may or may not require treatment. Some murmurs are considered to be innocent or physiological, meaning there is no underlying cardiac disease. Other murmurs are considered to be pathological, meaning there is an underlying disease process causing the abnormal sound.
Not all heart murmurs sound the same.
They are graded from I to VI based on the intensity of the ‘whooshing’ sound. They are also characterised by how long the ‘whoosh’ sound lasts throughout the heartbeat, and where on the chest the murmur is loudest.
What Causes a Heart Murmur?
- Congenital Heart Defects: These are conditions that encompass a range of structural abnormalities of the heart that have occurred during development in utero and are present at birth. Such conditions include patent ductus arteriosus, atrial septal defect, ventricular septal defect, Tetralogy of Fallot, subaortic stenosis and pulmonic stenosis.
- Valve Disorders: Problems with the heart valves within the heart. Valves are responsible for ensuring blood flows in a forward manner through the heart. Problems with these valves can result in leakage or backflow of blood between heart chambers.
- Cardiomyopathy: Diseases of the heart muscle, such as hypertrophic cardiomyopathy (i.e. thickening of the heart muscle) or dilated cardiomyopathy (stretching of the heart muscle) that reduce the ability of the heart to contract effectively.
- Infections or Inflammation: Conditions such as endocarditis or myocarditis can affect heart function.
- Anaemia: A low red blood cell count, resulting in thinner and more watery blood that creates more turbulence as it flows through the heart.
- Hypoproteinaemia: A low protein level in the bloodstream which, similar to anaemia, causes thinner blood and more turbulent flow.
- Hyperthyroidism: The overproduction of thyroid hormone causing increased heart rate and irregular heart rhythms that can result in the development of a heart murmur.
Diagnosing a Heart Murmur
The first step in the diagnosis of a heart murmur is for your veterinarian to detect the heart murmur when listening to your pet’s heart with a stethoscope. Once the murmur has been detected and characterised, the next step is to determine what exactly is causing that murmur with further diagnostic testing.
Though some murmurs can be benign, many are not and can indicate cardiac disease that will progress and worsen over time. It is for this reason that further diagnostic testing is of paramount importance so that the most appropriate plan can be made to treat the problem or delay the progression of the disease.
The following diagnostic tests may be recommended by your veterinarian:
- Echocardiography: Using ultrasound to examine all structures within the heart and assess the function of the valves and size of the heart chambers. The direction and velocity of blood flow can also be examined at this time. Ultrasound is the best and most accurate tool to diagnose the cause of a heart murmur and determine prognosis.
- Thoracic Radiographs: Taking x-rays of the chest to assess the size and shape of the heart and detect fluid in the lungs.
- Electrocardiogram (ECG): Used to detect arrhythmias or abnormal heart rhythms.
- Blood Tests: To check for systemic conditions like anemia or thyroid disease that could contribute to a murmur.
Managing and Treating Heart Murmurs
Treatment for a heart murmur depends on the underlying cause and its severity.
In many cases, especially with innocent or low-grade murmurs, no treatment is necessary; however, regular monitoring is recommended. If the murmur is linked to a significant cardiac issue, management options may include:
Medications: Drugs like diuretics to reduce the accumulation of fluid in the lungs or abdomen, ACE inhibitors to reduce blood pressure, pimobendan to increase the strength of cardiac contraction, and various others to control arrhythmias or blood flow through the circulation.
Surgery: In cases of congenital defects, corrective surgery might be recommended.
Regular Monitoring: Periodic check-ups and diagnostics to track progression and adjust treatment as needed.
Conclusion
We understand that the detection of a heart murmur in your pet can be concerning and overwhelming, but with prompt diagnosis and appropriate management, many pets live long, happy and healthy lives. Early diagnosis with imaging is crucial to either curing or delaying the progression of a disease. If you have any questions about your pet’s heart health, schedule an appointment with our veterinarians today. Or give our experienced vets a call – we’re happy to help.
