As a pet owner, hearing your veterinarian mention a heart murmur in your cat’s examination can be concerning. Cat heart murmurs are relatively common and are often detected during routine checkups. However, it’s important to understand what a heart murmur is, what might cause it, and when you should be concerned about your cat’s health.
What is a Heart Murmur?
A heart murmur is an abnormal sound heard during a heartbeat, often described as a whooshing or swishing sound. This sound occurs when blood flows through the heart or blood vessels in an unusual way. Murmurs are graded on a scale from 1 to 6, with higher grades indicating a louder or more significant murmur.
A heart murmur doesn’t always indicate a serious problem. In many cases, cats with mild murmurs live normal, healthy lives. However, it can also be a sign of an underlying heart condition that requires attention.
Causes of Cat Heart Murmurs
Heart murmurs in cats can be caused by a variety of factors. They may arise from structural abnormalities in the heart or could be a result of another condition affecting blood flow.
1. Congenital Heart Conditions
Some kittens are born with heart defects that can cause murmurs. Conditions like ventricular septal defects (VSD) or patent ductus arteriosus (PDA), where blood flow is abnormal due to a hole in the heart or a vessel that doesn’t close properly, can lead to murmurs. These congenital issues are relatively rare but are often identified early in life.
2. Heart Disease
The most common cause of heart murmurs in adult cats is heart disease. One of the most frequent types of heart disease in cats is hypertrophic cardiomyopathy (HCM), which is the thickening of the heart walls. HCM can result in turbulent blood flow, leading to a murmur. Cats with HCM may show signs of heart failure, including lethargy, difficulty breathing, and fainting.
Endocarditis (infection of the heart valves) and valvular disease (damage to the heart valves) can also lead to murmurs.
3. Hyperthyroidism
Hyperthyroidism is another common condition in older cats that can contribute to the development of a heart murmur. It causes an increase in metabolism and can lead to an elevated heart rate, which may result in a murmur.
4. Anemia
Severe anemia, where the cat has a low red blood cell count, can lead to a murmur due to reduced blood viscosity. This can cause abnormal blood flow and, in turn, a murmur.
5. High Blood Pressure (Hypertension)
High blood pressure, often associated with kidney disease or hyperthyroidism, can cause changes in the heart and blood vessels, leading to a murmur.
6. Physiologic Regurgitation (Innocent Murmur)
In some cases, heart murmurs can be caused by physiologic regurgitation, a benign and normal condition where a small amount of blood flows backward through a heart valve. This regurgitation happens because of slight imperfections in the heart valve closure but does not result in any significant health problems. Physiologic murmurs, or innocent murmurs, are most commonly observed in young cats, especially kittens under 6 months of age, as their hearts are still maturing. Some murmurs in young cats may resolve as they grow and their cardiovascular system matures.. Even in healthy adult cats, mild murmurs may be detected, and these are typically harmless.
Physiologic murmurs are typically Grade 1 or 2 and are usually not associated with any other symptoms. Unlike pathologic murmurs, they do not lead to heart failure, difficulty breathing, or other clinical signs.
When to Worry: Symptoms to Watch For
While a murmur itself doesn’t always indicate a severe problem, it’s crucial to monitor your cat’s overall health. If your cat exhibits any of the following signs, it’s essential to consult your veterinarian:
- Lethargy or Fatigue: If your cat seems more tired than usual, it may indicate a problem with their heart.
- Difficulty Breathing: Cats with heart issues may struggle to breathe or show signs of labored breathing.
- Fainting or Collapsing: Fainting episodes or sudden collapse may indicate a more severe underlying heart condition.
- Coughing: A persistent cough, especially if it’s wet or harsh, may be a sign of heart failure or fluid buildup in the lungs.
- Loss of Appetite: If your cat suddenly loses interest in food or shows significant weight loss, this could be linked to heart or other systemic problems.
In addition to these symptoms, if the murmur is associated with other abnormal findings during a veterinary exam (such as a heart rate that is too fast or too slow), further investigation is needed.
Diagnosing and Treating Heart Murmurs
If a heart murmur is detected, your veterinarian may recommend diagnostic tests to determine the cause. These may include:
- Echocardiogram (Ultrasound of the Heart): This test uses sound waves to create detailed images of the heart and can help identify structural abnormalities, such as heart disease or congenital defects.
- X-rays: X-rays can help assess the size and shape of the heart and detect fluid buildup in the lungs, a sign of heart failure.
- Electrocardiogram (ECG): This test measures the electrical activity of the heart to identify any arrhythmias.
- Blood Tests: Blood work can help assess kidney function, thyroid levels, and other systemic issues that may contribute to a murmur.
Treatment depends on the underlying cause of the murmur. If the murmur is linked to heart disease such as HCM, treatment may include medications to manage heart failure, reduce fluid buildup, and regulate blood pressure. In cases of hyperthyroidism or anemia, treating the underlying condition may help resolve or reduce the murmur.
Conclusion
While a heart murmur in your cat can be alarming, it’s not always a sign of a serious condition. Many cats with murmurs go on to live normal, healthy lives. Physiologic murmurs, in particular, are common in kittens and adult cats, often without any negative health impact. However, it’s important to work with your veterinarian to understand the cause and take any necessary steps to manage your cat’s health. Regular checkups and diagnostic tests can help catch heart issues early, giving your cat the best chance for a long, happy life.
Sources:
- “Hypertrophic Cardiomyopathy in Cats,” American Veterinary Medical Association (AVMA). Link
- “Heart Murmurs in Cats,” Cornell University College of Veterinary Medicine. Link
- “Feline Hyperthyroidism,” American Animal Hospital Association (AAHA). Link
