Heart Murmurs in Cats: Types, Symptoms, Causes and Treatment

A heart murmur is an unusual sound that can be heard with a stethoscope when listening to a cat’s heartbeat.

Murmurs are commonly described as a whooshing sound and are a result of unstable blood flow in the heart.

Read on learn more about the types, causes, symptoms and the treatment options available as advised by pet experts.

Types of Heart Murmurs in Cats

According to PetMD, heart murmurs are graded by their intensity on a scale of 1 – 6.

  • Grade I: barely audible
  • Grade II: soft, but can be easily heard with a stethoscope
  • Grade III: moderately loud
  • Grade IV: loud; light palpation can be felt when touching the cat’s chest
  • Grade V: very loud and can be heard with stethoscope barely touching the chest
  • Grade VI: so loud that it’s audible even without using a stethoscope; palpitations can be felt through the chest

The grade of the murmur doesn’t represent the severity of your cat’s condition. It’s simply a way to describe its loudness and shouldn’t be a cause for alarm.

Causes of Heart Murmurs in Cats

Grey cat lying on a tube

Benign Causes of Heart Murmurs

These causes will result in innocent heart murmurs which are harmless, and generally don’t require any medical intervention.

Innocent heart murmurs are relatively common among young kittens and tend to stop when the cats are 4 – 5 months old. Older cats may also have these heart murmurs because of stress, which causes their heart rate to increase.

Extracardiac Conditions

These are conditions that occur outside the heart, and they can include

  • Anaemia (low levels of red blood cells)
  • High blood pressure
  • Hyperthyroidism (an excess of thyroid hormone)
  • Hypoproteinaemia (low levels of protein in the blood)
  • Fever
  • Obesity

Structural Heart Diseases

Cats suffering from structural heart diseases have some sort of abnormality that disturbs the regular flow of blood, resulting in heart murmurs. These issues can include a leaky heart valve or a hole in your cat’s heart.

Additionally, these diseases can be congenital – this means that your cat is born with a heart defect. It can also be developed later in your cat’s life.

Symptoms of Heart Murmurs in Cats

Grey cat lying inside a basket

There are no physical symptoms of heart murmurs since they can only be heard using a stethoscope.

However, there’s a possibility that your pet’s suffering from an underlying heart problem if it has the symptoms listed below.

  • Loss of appetite
  • Unexplained weight loss
  • Difficulty in breathing
  • Lethargy
  • Noisy breathing
  • Stunted growth in kittens

How Are Heart Murmurs in Cats Diagnosed?

In most cases, heart murmurs are detected when your veterinarian listens to your cat’s heart with a stethoscope.

What Happens if Your Cat Has Been Diagnosed with a Heart Murmur?

Person scratching a cat's chin

If a heart murmur is detected during the check-up, a series of questions regarding your cat’s health will be asked. These questions allow your vet to better understand your pet and will help with deciding on the next steps to take.

If Your Cat Displays No Signs of a Health Problem

Your vet may suggest a periodic examination to reassess the heart murmur if your cat is generally healthy and shows no signs of a health problem.

Similarly, as this condition is common among younger cats, your vet may opt to re-examine your pet if it’s still a kitten.

If Your Cat Displays Signs of a Health Problem

If there are signs of a heart condition, further diagnostic testing is required to identify the root cause of the issue.

Some examples of these tests include:

 Chest radiographs

A chest radiograph is an x-ray of the heart that allows the vet to detect if there are any physical abnormalities in your cat’s heart.


An echocardiogram is the test of choice for cats with suspected heart disease. It’s an ultrasound scan of the heart to evaluate your cat’s heart function, identify abnormalities or the presence of existing heart conditions.

 Blood tests

The relevant blood tests can check for health problems like anaemia that can cause or aggravate your cat’s condition.

How to Treat Heart Murmur in Cats?

Cat eating at home

According to  Austin Benoit of Bone & Yarn, the types of treatment option offered will vary based on the cause of the murmur. If the heart murmur is found to be harmless, no treatment is necessary.

However, it’s advised that you keep a close eye on your cat’s health to ensure that no other issues arise.

Further action needs to be taken if the heart murmur is caused by an underlying health issue. This is especially important if it’s affecting the function of your cat’s heart.

Depending on the severity of your pet’s condition, your vet may recommend surgery or medication. Your cat may also be put on a special diet or other forms of specialised care.

Caring for a Cat with Heart Murmur

Most conditions associated with a heart murmur can be treated. The most important thing to do is to diagnose these conditions in their early stages and begin addressing them as soon as possible.

When caring for a cat with a heart murmur, you’re encouraged to send her for routine check-ups.

This allows you to monitor how well she’s responding to treatment and ensure her condition hasn’t changed or gotten worse.


  • Madeleine Seah


    As an avid home baker, Madeleine spends a significant portion of her free time scouring the internet for recipes for next her baking project. When she’s not hands deep in kneading some form of dough, you can find her making music with a bunch of like-minded musicians at her alma mater’s alumni band.


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