By Courtney Prue | March 21, 2025

Heart Murmur In Cats: Causes, Symptoms, And Treatments

What is a Heart Murmur in cats?

A heart murmur is an abnormal sound heard when listening to a cat’s heart with a stethoscope. Normally, a cat’s heart produces two distinct sounds, described as “lub” and “dub.” A heart murmur in cats is an extra sound that can be heard between the two sounds, creating a “shooshing” or “whooshing” sound. This sound indicates turbulent blood flow through the heart. This turbulence can be created by any change to the normal smooth movement of blood through the heart. This includes narrowing, expansion, obstructions, other structural changes and changes to the consistency of the blood.

A heart murmur’s grade, ranging from 1 to 6, describes the loudness of the murmur. A grade 1 heart murmur in cats is soft, while a grade 6 heart murmur is loud and palpable. In cats, the grade of the murmur does not always provide information about the severity of the heart disease.

Are there different types of heart murmurs in cats?

A heart murmur in cats can either be temporary and innocent or can be due to a ‘cardiomyopathy’ which refers to any disease that affects the heart muscle.

Temporary, innocent murmurs do not impact a cat’s health and the murmur usually goes away when the underlying reason has been addressed or changed. This includes when they are:

• Kittens, up to 6 months of age
  Stressed or anxious
  Anaemic or have low protein in the blood
  Pregnant
  Feverish
  Have hyperthyroidism (Note: long-term uncontrolled hyperthyroidism can cause irreversible damage to the heart)

All of these things cause the heart to work harder, causing increased turbulence and therefore a murmur. Some of these conditions can impact the health of the cat, but the murmur itself is not necessarily a concern.

What is the most common heart disease in cats?

Cardiomyopathies (heart disease) are irreversible and can progress in severity over time, with the potential to greatly impact a cat’s health. Types of heart disease include:

• Hypertrophic Cardiomyopathy (HCM): HCM is the most common form of heart disease in cats, accounting for 80-90% of all cases. It is characterised by the thickening of the heart muscles, making it difficult for the heart to pump blood effectively.
• Dilated Cardiomyopathy (DCM): DCM is characterised by the weakening of the heart muscles, which leads to the heart becoming enlarged and less able to pump blood effectively.
• Other rare types include Restrictive Cardiomyopathy (RCM), Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and Mitral Valve Disease (MVD)

What causes heart disease in cats?

• Genetics: Some breeds of cats, such as Maine Coons and Ragdolls, are more prone to developing heart disease.
• Age: As cats get older, their risk of developing heart disease increases.
• Diet: Poor nutrition can contribute to the development of heart disease.
• Underlying health conditions: Diseases such as hyperthyroidism, hypertension, and kidney disease can increase the risk of heart disease.

What are the signs of heart disease in cats?

• Lethargy or weakness
• Decreased exercise tolerance
• Difficulty breathing
• Rapid breathing or panting
• Loss of appetite
• Weight loss
• Coughing or gagging

Can my cat have a heart attack?

It is important to know the symptoms that indicate a medical emergency in cats with heart disease, as prompt veterinary attention can be life-saving. Here are some symptoms to watch out for:

• Difficulty breathing: This can manifest as panting, open-mouthed breathing, or rapid breathing. If your cat is struggling to breathe, it is a medical emergency.
• Bluish or pale gums: This can be a sign of poor oxygenation and should be evaluated by a veterinarian immediately.
• Weakness or collapse: This may indicate poor blood flow to vital organs and requires immediate veterinary attention.
• Sudden onset of paralysis: This can be a sign of a blood clot, which can be a life-threatening complication of heart disease.
• Loss of consciousness: This can occur suddenly and may be a sign of cardiac arrest, which requires immediate cardiopulmonary resuscitation (CPR).

If you observe any of these symptoms, seeking immediate veterinary attention is important. Time is critical in emergency situations, and a delay in treatment can have serious consequences for your cat’s health. Don’t hesitate to call your veterinarian, or an emergency veterinary clinic for guidance on how to proceed.

What are the side effects of heart disease in cats?

Heart disease can have significant impacts on other parts of the body. Such impacts include:

• Congestive heart failure: This occurs when the heart is unable to pump blood effectively, leading to a backup of fluid in the lungs and other organs. Symptoms may include coughing, difficulty breathing, and lethargy.
• Blood clots: Heart disease can cause the formation of blood clots in the heart, which can travel to other parts of the body and cause serious damage. This is known as thromboembolism and can cause sudden pain and paralysis in the hind legs.
• Arrhythmias: Heart disease can cause abnormal heart rhythms, or arrhythmias, which can be life-threatening if left untreated.
• High blood pressure (hypertension): The body can compensate for an inefficient heart by increasing the blood pressure, which can cause secondary damage to other organs

How is heart disease diagnosed in cats?

Diagnosing and monitoring heart disease in cats typically involves:

• Physical exam. Your vet might recommend a recheck in 1-3 months to see if the murmur is still present, or if it was temporary.
• Blood tests, including testing for the thyroid hormone
• Imaging tests such as X-rays, echocardiography (heart ultrasound), or electrocardiography (ECG or electrical activity monitoring)

These tests will determine how severe the heart disease is, what type is occurring, how it is progressing and help direct treatment efforts.

Can heart disease in cats be treated?

The treatment options for cats with heart disease depend on the severity of the condition and are aimed at reducing the risk or impact of the most common complications. Treatment options include:

• Medications: There are several different types of medications that can be used to treat heart disease in cats, including:
  • Diuretics to help remove excess fluid from the body
  • ACE inhibitors to help dilate blood vessels and reduce blood pressure
  • Beta-blockers to slow the heart rate and reduce the workload on the heart
  • Antiplatelets or anti-coagulants to reduce the risk of clot formation
• Special diet: Some cats with heart disease may benefit from a special diet that is low in sodium and high in certain nutrients, such as taurine and L-carnitine.
• Oxygen therapy: In cases where the cat is having difficulty breathing, oxygen therapy may be necessary to provide additional support.
• Surgery: In some cases, surgery may be necessary to correct certain types of heart disease, such as a congenital defect.

The medical management and monitoring of heart disease can be confusing and overwhelming. Get in touch with our team today for a personalised discussion.

How do I manage my cat’s heart disease at home?

Here are some tips to help you optimise your cat’s care at home:

• Monitor your cat’s breathing: This includes the effort used, as well as the rate. An important factor to monitor is their resting respiratory rate. While deeply asleep, count the number of breaths taken in 1 minute (or in 15 seconds and then multiply by 4). The rate should be between 10-20. If it is over 30 breaths per minute, ring the vet ASAP as this indicates possible congestive heart failure.
• Create a comfortable living space: Ensure your cat’s living space is warm, quiet, and comfortable. Provide soft bedding, and ensure the area is clean and free of drafts.
• Manage stress: Stress can worsen your cat’s heart disease. Try to minimise stress by keeping their routine consistent, minimising loud noises, and providing a calm environment.
• Regular check-ups: Your vet will monitor your cat’s condition and make changes to their treatment plan as necessary.

An at-home veterinary assessment can also be helpful to identify any other areas of improvement that can help your beloved cat stay comfortable for as long as possible.

How long can my cat live with heart disease?

The prognosis for cats with heart disease varies depending on the type and severity of the condition, as well as the cat’s overall health and response to treatment. Some cats may be able to live for several years with appropriate treatment and care, while others may experience a more rapid decline in health.

End-of-life care tips

If your cat’s heart disease has progressed to a point where treatment is no longer effective or its symptoms are too severe, it’s important to consider end-of-life care options, including possibly putting your cat to sleep (euthanasia). This can be an overwhelming and distressing thing to even think about. Rest Your Paws is here to support you and provide compassionate care for your beloved pet throughout their journey.

Here are some end-of-life care tips for cats with heart disease:

• Keep them hydrated and well-nourished with some delicious food.
• Spend quality time with them, making the most of every moment, such as with a bucket list.
• Offer a calm and peaceful environment, free from stressors that can exacerbate symptoms.
• Administer medications as prescribed for pain management and symptom relief. Your veterinarian may increase doses of medications such as diuretics to reduce fluid accumulation.
• Provide a warm and comfortable space for your cat to rest and sleep, with easy access to food, water, and a litter box.
• Monitor your cat’s breathing, heart rate, and overall condition, and seek veterinary attention if necessary.
• Evaluate their quality of life regularly, or reach out to a palliative care vet to help you with this.
• Consult our End of Life Care Pack to get prepared to put your cat to sleep.
• Track good days and bad days on our Quality of Life Assessment Calendar.

Heart disease in cats is a serious and complex condition that requires attentive care and management. With appropriate treatment and end-of-life care options, many cats can live for several years with a good quality of life. By understanding the causes, symptoms, diagnosis, treatment, and end-of-life care options for heart disease in cats, pet owners can make informed decisions and provide the best possible care for their furry companions. Rest Your Paws is committed to supporting pet owners throughout every step of their pet’s health journey and hopes that this resource has provided valuable insights and tips to help pet owners care for their cats with heart disease. Please do not hesitate to reach out to us if you have any questions or concerns – we are here to help.

Rest Your Paws

We offer in-home pet euthanasia for dogs, cats and other pets. Say goodbye with peace and dignity to your beloved pet. Professional and experienced end-of-life support.