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MCV FAQ: "I've learnt my cat has a heart murmur - what does this mean?"

Updated: Jun 16

Heart murmurs in cats, often discovered during routine veterinary check-ups, can be a sign of underlying heart conditions that require attention. This blog post delves into the nature of heart murmurs, their causes, their diagnosis, and the implications for our beloved feline companions.


What is a Heart Murmur?

A heart murmur is an unusual sound heard during or between heartbeats. It tends to be a whooshing noise we can detect using a stethoscope. Murmurs arise from turbulent blood flow within the heart or the large vessels exiting the heart, differing from the normal "lub-dub" sounds of a healthy heartbeat. According to a study published in the Journal of Feline Medicine and Surgery, heart murmurs are detected in approximately 16-21% of asymptomatic cats presented for routine examinations (1).



a tabby cat being examined
Litenting to the heart with a stethoscope is an important component of a through health check

The Causes: From Innocuous to Serious

Heart murmurs in cats can stem from various causes, ranging from benign to serious health issues.

Some common causes include:

- Structural heart disease: Conditions like hypertrophic cardiomyopathy, the most common form of heart disease in cats, can lead to murmurs. Studies indicate that HCM affects approximately 10-15% of the general cat population, particularly in certain breeds such as the Maine Coon, Ragdoll, Sphynx and British Shorthair (2).

High blood flow conditions: Anemia or hyperthyroidism can increase blood flow through the heart, resulting in murmurs.

- Valve dysfunctions: Abnormalities in the heart valves can disrupt normal blood flow, causing murmurs.

- Congenital issues: Some cats are born with heart defects that result in murmurs.

It's important to note that not all murmurs indicate heart disease.


In some cases, murmurs can be transient or occur in situations of stress, and they may not necessarily signal a serious condition.



A black and white cat undergoing echocardiography
Echocardiography is a specialised ultrasound technique that requires precision and training

Determining the Cause of Heart Murmurs in Cats

Discovering a heart murmur typically leads to further investigations to determine its cause.

Diagnostic steps may include:

- Echocardiogram (Echo): An ultrasound of the heart, providing detailed images of the heart's structure and function.

- Chest X-rays: To evaluate the shape and size of the heart and the state of the lungs.

- Electrocardiogram (ECG): To assess the heart's electrical activity.

- Blood and urine tests can help identify underlying conditions that might contribute to the murmur, such as hyperthyroidism or kidney disease.


Below is an example of a heart ultrasound technique called "colour-flow" Doppler demonstrating a leak in one of the heart valves.




Treatment and Management

The approach to treating heart murmurs in cats depends on the underlying cause. If a specific heart condition is identified, treatment might include medications to improve heart function, manage symptoms, or address the primary disease causing the murmur.


In cases where the murmur is linked to a non-cardiac issue, such as hyperthyroidism, treating the underlying condition can often reduce or eliminate the murmur.


For benign or physiological murmurs, no treatment may be necessary, but regular monitoring and check-ups are essential to ensure that no underlying conditions develop.



A tabby cat taking a tablet
Many cats with heart disease will benefit from medication to prevent the formation of blood clots in the heart and to keep signs of congestive heart failure at bay.

Conclusion

Learning that your cat has a heart murmur can be concerning. Still, modern veterinary medicine offers effective management for many related conditions, helping your feline friend maintain a good quality of life.


The key to handling heart murmurs in cats is regular vet check-ups, early detection, and appropriate care.



References:

  1. Paige CF, Abbott JA, Elvinger F, Pyle RL. Prevalence of murmurs and heart disease in healthy cats with murmurs. J Feline Med Surg. 2009.

  2. Meurs KM. Hypertrophic Cardiomyopathy: Inherited Cardiac Disease in Cats. Compend Contin Educ Vet. 2010.

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