Hypertrophic Cardiomyopathy in Cats - Symptoms, Causes, Diagnosis and Treatment

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Doctor veterinarian at clinic.
Doctor Veterinarian At Clinic.

While everything often looks alright on the outside, your cat may have something going on internally. Hypertrophic cardiomyopathy is one of those silent diseases that cats are unfortunately very prone to developing. Some breeds of cats are more likely to develop this disease than others, but it is still something all cat owners should be aware of. Knowing what signs to look for can help this problem from going undetected.

What Is It?

Hypertrophic cardiomyopathy, often abbreviated as HCM, is a condition of the heart that causes the walls, specifically the left ventricle, to thicken. This makes it harder for the heart to work properly. The heart is a muscle with chambers inside of it that pump blood. If the walls of the heart become too thick, then it won't be able to properly pump blood. The left ventricle is one of four heart chambers, but it specifically takes primary responsible for pumping blood through the body. If it can't do its job, the rest of the body does not get proper blood flow.

Blood can also back up and clots can form if the heart isn't working properly. In HCM, the heart tries to beat faster to compensate for the lack of proper blood flow. In doing so, it depletes the body of oxygen, which then kills heart cells. When the cells die, the heart function decreases even more and abnormal heartbeats occur. Congestive heart failure is also a common occurrence in cats who have HCM, partially due to the backup of blood.

calico cat lying on white comforter
calico cat lying on white comforter


Because HCM happens internally, it often comes as a surprise to cat owners. Heart issues may not be obvious until a cat is having problems, so it is important to know what to watch for.

A good physical examination will include auscultation, where your doctor will listen to your cat's heart with a stethoscope. Your vet will be searching for normal heart rhythm, a murmur, or an arrhythmia. If an arrhythmia or murmur is heard, it may be an indication of heart disease such as hypertrophic cardiomyopathy. An X-ray and an ultrasound of the heart, called an echocardiogram, may be recommended to further assess your cat's heart. These tests won't fix a heart problem, but they can give your veterinarian a diagnosis and therefore a potential treatment plan.

Labored breathing is usually identifiable by observing your cat taking quick breaths. A cat struggling to breathe may also have audible wheezes, its abdomen rising and falling instead of the chest, an open mouth or heavy panting, and pale or blue gums. If your cat isn't able to move oxygen through its lungs, it will have difficulties breathing and may be weak or collapse.

white and black cat on rock
white and black cat on rock

Sudden hind limb paralysis is a scary symptom that can also be a result of HCM. If a clot travels out of the heart and blocks blood flow to the hind limbs, your cat will appear to be paralyzed. This can happen quite suddenly, and due to the lack of blood flow, the leg will feel cold to the touch. Sudden death can also occur due to clots, but this is rare.


  • Labored breathing
  • Open-mouth breathing
  • Pale or blue gums
  • Collapse
  • Weakness
  • Irregular heartbeat
  • Hind limb paralysis
  • Sudden death


Certain breeds of cats are more likely to develop hypertrophic cardiomyopathy than others. Maine Coons, Ragdolls, Persians, Sphynx, Chartreux, and British Shorthair breeds have shown to have a suspected genetic predisposition to HCM and are therefore more prone to developing it. It is unknown why these breeds are more likely to get HCM than others. But, if you have one of these cats, it is especially important to closely monitor your cat's heart health so you can catch HCM early.

Other breeds of cats can also develop hypertrophic cardiomyopathy, but the reason why is still unknown. Some dietary components and obesity may play a role in heart disease in cats, but there is no definitive link between hypertrophic cardiomyopathy and a specific cause.

black tabby cat lying on white surface
black tabby cat lying on white surface
brown tabby cat in close up photography
brown tabby cat in close up photography


Since hypertrophic cardiomyopathy cannot be cured, the goal of treatment is to keep the heart rate normal, prevent blood clots from forming inside your cat, and make it easy for your cat to breathe. While this is more of a management plan than a treatment plan, it's the best option until a cure or further research has been done.

  • Nutrition: Taurine and L-carnitine are amino acids that are often recommended as supplements for cats with heart disease. These ingredients are often added to pet food and are also produced naturally within a cat's body. Research has shown that they may be beneficial in supporting a healthy heart but they are not treatments of hypertrophic cardiomyopathy specifically, just overall heart health. Omega-3 fatty acids and special diets formulated for cats with heart disease may also be beneficial in supporting cats with hypertrophic cardiomyopathy.
  • Medications: There are several drugs that might be prescribed to help manage the symptoms of HCM. Some medications may be injected, applied topically, or administered in pill form. Different drugs will help make breathing easier, assist the heart's function, stabilize blood pressure, and address other potential symptoms of HCM.
  • Activity level: Your veterinarian may recommend keeping your cat's activity level low in order to decrease the amount of work its heart has to do.


Since there is no known definitive cause, there is not a concrete way to know if you are preventing hypertrophic cardiomyopathy. Providing proper nutrition to support the heart and ensuring your cat gets an annual veterinarian examination will help keep your cat healthy and hopefully decrease the likelihood of diseases, including hypertrophic cardiomyopathy.


If hypertrophic cardiomyopathy is suspected, your cat will most likely have blood work, X-rays, blood pressure testing, and an echocardiogram performed to fully assess the health of your cat. Based on the findings of those tests, your veterinarian will recommend a treatment plan to help diminish the symptoms or delay the progression of the disease.