Get To Know Your Pet – All About Cardiomyopathy in Cats

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What is Cardiomyopathy in Cats?

Cardiomyopathy in cats, what is it? What are the causes and treatment options? Today we are going to answer these questions and more as we delve into this potentially fatal condition.

cardiomyopathy in cats

Cardiomyopathy is a disease of a cat’s heart muscle. The heart acts like a giant pump in the body, helping to move blood around to vital organs providing nutrients, oxygens and removing waste and carbon dioxide. The heart is made up of a special type of muscle called cardiac muscle (myocardium), which is triggered to contract by electrical impulses created inside the muscle!

When the heart muscle becomes diseased, it will change in shape and size. These changes can initially be beneficial but become more severe as the changes continue and can eventually cause further problems leading to a condition called congestive heart failure, whereby blood becomes backed up, much like a traffic jam, and fluid is forced out into the body cavities.

Any disease which affects cardiac muscle will cause problems with the pumping of blood and can be life-threatening. The good news is, with modern medicine, there are great options to help diagnose and treat cardiomyopathy, and we explain this below.

There are three types of primary cardiomyopathy in cats, as discussed below: 

  1. Hypertrophic
  2. Restrictive, and 
  3. Dilated

Cardiomyopathies primarily affect adult cats, and although all cats are susceptible, a genetic predisposition for the disease has been shown in Maine Coons, Ragdolls, and some American Shorthair breeds. 

How do Vets Diagnose Feline Cardiomyopathy?

There are many different ways a veterinarian can suspect and diagnose cardiomyopathy, and these are listed below.


In discussion with an owner, a veterinarian might suspect cardiomyopathy. History involving signs of difficulty breathing, open mouth breathing, reduced exercise, lethargy,  cat coughing, and an increased breathing rate at rest can all occur in cats with cardiomyopathy.

Clinical Examination

When a veterinarian examines a cat with cardiomyopathy, some common findings include a rapid or irregular heartbeat, a cat heart murmur, increased respiratory rate, increased respiratory sounds, abnormal feeling pulses, and fluid in the abdomen (abdominal ballottement). 

A cat with little to no feeling in its hindlimbs could also have heart disease-causing Feline Aortic Thromboembolism. This is discussed in more detail below.


Radiographs can show changes in heart shape, such as bulges or general enlargement. There can also be signs in the abdomen or chest showing fluid build-up from heart failure. Ultrasounds can also be performed on the heart (echocardiogram), showing changes to the muscle, valves, and the abnormal flow of blood through the heart’s chambers.

Blood test

A blood test called ProBNP can be performed, which can show damage to the heart muscles and give an indication of heart disease.

Electrocardiogram (ECG)

ECGs show the heart’s electrical activity by connecting metal clips to different parts of the cat’s body and measuring the changes in electrical signals traveling across the body. Changes to the normal expected pattern can help with diagnosing disease of the heart.

Other tests

Other tests can help diagnose cardiomyopathy; these include blood pressure measurement, examination of the retina in the eye, and other blood tests for specific diseases that can secondarily affect the heart (e.g., hyperthyroidism, kidney disease).

The Causes of Cardiomyopathy in Cats

There are many different types of cardiomyopathy in cats. Still, one thing they have in common is that the heart muscle will respond in one of three ways, it will either become hypertrophic, restrictive or dilated.

Causes of heart disease can be separated into primary and secondary cardiomyopathy. Primary cardiomyopathy means that the condition is due to a root cause of illness in the heart. In contrast, the secondary disease is where cardiomyopathy is a sequela to a primary illness elsewhere in the body, e.g., in the thyroid gland.

Examples of causes from both primary and second cardiomyopathy follow below:

Primary causes

  • Genetic heart conditions. The breed Maine Coone is genetically linked to developing hypertrophic cardiomyopathy (HCM). A genetic mutation has been shown to be linked to the development of HCM in Maine Coone, which can be tested for.
  • Deficiency of taurine in the diet. Historically cat foods didn’t have taurine (an essential amino acid), which led to cases of dilated cardiomyopathy (DCM). Nowadays, all good quality cat foods have taurine added to prevent this disease.
  • Infiltrative disease. Cancer such as lymphoma can invade the cardiac muscle and cause disease.
  • Toxins. Some toxins can cause heart disease when ingested. For example, a drug called Digoxin which can be used for treatment can quickly become toxic if too much is given and can damage the heart muscle.
  • Idiopathic heart disease. These are a group of conditions where the exact cause is never found.

Secondary causes

  • Hyperthyroidism is a disease where the thyroid gland in the neck overproduces thyroid hormone. This increase in thyroid hormone has many different effects on the body, including the heart. Hyperthyroidism makes the heart beat much faster than usual, leading to hypertrophy of the muscle, leading to disease.
  • Kidney failure can cause an increase in blood pressure which can put an increased load on the heart leading to hypertrophy of the cardiac muscle. 

Available Treatment Options to Combat Feline Cardiomyopathy

The treatment of cardiomyopathy depends on the cause. In some cases where an underlying cause is found and treated, the heart disease may improve or even be reversed. Hyperthyroidism can frequently be treated, and if caught early enough, there can be a complete resolution of the cardiomyopathy. 

Where no cause is found, or the treatment is difficult or non-responsive, then treatment involves managing signs of disease.

The exact treatment varies, but some examples of medicines include:

  1. Diuretics are used when a cat is in congestive heart failure to help remove excess fluid which builds up in the abdomen or the chest.
  2. Beta-blockers help to reduce heart rate if it is too rapid.
  3. Calcium-channel blockers help with heart muscle relaxation to ensure effective filling and pumping of blood in the heart.
  4. Aspirin can be helpful in some instances with the prevention of blood clots. However, it is essential to note this medication should only be prescribed by a veterinarian as it can be toxic in high doses.
  5. Angiotensin-converting enzyme (ACE) inhibitors help with cardiomyopathy leading to congestive heart failures.
  6. Drugs to lower blood pressure are useful when there is hypertension, e.g., with some cats in kidney failure.

Prognosis varies depending on the disease, how well the condition is treated, and any other diseases a cat might be dealing with. For example, an otherwise healthy cat with hyperthyroidism diagnosed and treated early would likely have a much better prognosis than a Maine Coon with genetic hypertrophic cardiomyopathy that doesn’t get diagnosed until late in the disease process and doesn’t get appropriate treatment.

Feline Aortic Thromboembolism (FATE) any cat with cardiomyopathy can develop a blood clot caused by abnormal blood flow through the heart. When this blood clot travels through the blood, we call this a thromboembolism. This thromboembolism can become lodged in the bifurcation of the aorta and cause a sudden onset of paralysis in the hind legs, which can be very serious and life-threatening.

Should a Cat with Feline Cardiomyopathy be Fed a Special Diet?

There are some important considerations to make in cats with heart disease, and one of those is diet. Any cat with heart disease should be checked to ensure it is being fed a diet with taurine added. If a cat is eating a vegan diet or dog food, it may be missing out on this vital amino acid, and this should be corrected immediately.

There are no specific cardiac diets available for our feline friends like there are for our canine companions. Instead, there are just general guidelines to be considered:

  1. Ensure adequate calories to maintain a good condition in your cat. Cardiac cachexia (weight loss caused by heart disease) can become quite severe, so a high-quality diet with adequate protein levels is essential.
  2. Omega-3 fatty acids have been shown to be beneficial for heart disease and can be supplemented in your cat’s diet. See some examples linked here:
  1. Sodium can be harmful to heart disease and should be reduced. Speak to your veterinarian for specific advice on current recommendations on the amounts of sodium your cat should be ingesting. Still, in general, you can look for treats low in sodium such as this.

Feline Cardiomyopathy can be a severe disease, but there have been incredible advances in understanding and treating this disease in recent years. More and more information becomes available every day. 

If your cat is diagnosed with any kind of heart disease, make sure to follow your veterinarian’s advice closely and ask them questions to clarify anything that you might be confused about. 

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For over 12 years, Sharmaine's had the privilege of working at game lodges, where she immersed herself in the world of wildlife. Hand-rearing both domestic and exotic animals has been a rewarding aspect of her career. This hands-on experience has given her invaluable insights into the unique needs and care requirements of various species.