What Does an Enlarged Heart Mean for Cats?

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An enlarged heart in cats is a common sign of heart disease.  There are several types of heart disease that can occur in cats and the different diseases can cause special structural changes in the heart. Below we will review the signs of an enlarged heart in cats, causes of an enlarged heart, tips for diagnosis of the underlying heart disease, and what you can do at home.

Signs of an Enlarged Heart in Cats

Signs of heart disease can vary depending on the severity of the disease. In early stages of heart disease, cats can appear normal. Some cats will have very subtle symptoms that may progress over time. Signs of heart disease in cats may include:

  • Noisy, difficult, open-mouthed breathing
  • Increased respiratory rate and/or increased respiratory effort (using abdominal muscles to breath)
  • Posture of help breathing such as squatting or lying with chest down, head extended and elbows pointed outward and back
  • Anorexia or lack of appetite
  • Weight loss
  • Lethargy
  • Sleeping more
  • Decreased social interactions with the family or other cats
  • Sudden inability to use one or more limbs and crying
  • Coughing (rare in cats, common in dogs)
  • Fainting
  • Your vet may auscultate a murmur- learn more about Murmurs in Cats. This is a very good article written by a veterinary cardiologist.

Some pet owners may attribute the subtle changes associated with heart disease in cats to changes to age in older cat or maturity in younger cats. As the heart disease progresses, there may be progressive weight loss, trouble breathing which can cause an increased breathing (respiratory) rate or increased effort. If you believe your cat has an enlarged heart or is having any difficulty breathing or is in pain, please see your veterinarian immediately.

Heart disease can be a cause of sudden and unexpected death.   Learn more about Sudden Cat Death: Understanding Why it Happens.

Causes of Enlarged Hearts in Cats

There are several causes of an enlarged heart in cats. They may include:

  • Hypertrophic cardiomyopathy (HCM) is common heart condition in cats characterized by a thickening of the main pumping chamber of the heart (the left ventricle) and not attributed to other medical conditions (such as high blood pressure). It can, in severe cases, cause heart failure when fluid accumulates in the lungs. Blood clots can form in the heart and travel to distant blood vessels obstructing blood flow to one or more limbs (especially the back legs). This is called a thromboembolism and can cause severe pain while having the inability or difficulty using one or more legs. HCM can be mild to life-threatening. Learn more about Hypertrophic cardiomyopathy (HCM) in Cats.
  • Dilated cardiomyopathy (DCM) in cats is a heart disease characterized by dilation or enlargement of the heart chambers and markedly reduced contraction. The heart muscle is often very thin and the ability of the heart to pump is diminished. An analogy of a normal functioning ventricle would be opening and closing your fist/hand completely. Using this analogy, the ventricle of a cat with dilated cardiomyopathy will only have a fraction of that full movement such as only the fingers moving slightly toward your palm but no full squeeze.  Some cats will have only one part of the heart involved or advanced case can cause all four heart chambers to be abnormally affected. Learn more about Dilated Cardiomyopathy (DCM) in Cats.
  • Another heart disease that may affect cats is Chronic Valvular Heart Disease.  Valvular heart disease (VHD) is a condition characterized by degeneration and thickening of the heart valves. Valvular heart disease is more common in dogs but can also occur in cats. The abnormal values can cause an enlarged cat heart and can eventually lead to heart failure. Accumulation of fluid in the lungs (pulmonary edema) or the abdomen (ascites) may occur.
  • Feline heartworm disease is caused by a parasite, Dirofilaria immitis, that is transmitted by mosquitoes.  Heartworm disease is less common in cats than dogs but can occur. Heartworm disease can cause an enlarged heart in cats. It can be diagnosed by blood tests and advanced testing such as an echocardiogram (Echo). Learn more about Heartworm Symptoms in Cats. This article has information about feline heartworm disease.
  • Congenital heart disease is a term used to describe abnormalities in the heart that develops before birth. There are many different types of defects that can affect different parts of the heart. These diseases can cause an enlarged heart in cats. The best way to diagnose congenital heart disease in cats is with an Echocardiogram performed by a board-certified veterinary cardiologist.

How Enlarged Hearts in Cats are Diagnosed

An enlarged heart in cats can be diagnosed by the following methods:

  • Chest X-rays – Also known as thoracic radiographs or X-rays of the chest, a chest X-ray can identify heart enlargement and fluid accumulations in or around the lungs. Chest X-rays can also be useful in excluding a number of other diseases.
  • Echocardiogram – Also known as an ultrasound examination of the heart or an “echo”, is the most sensitive diagnostic test that can determine not only if the heart is enlarged but also which part of the heart is abnormal and the severity of the disease. The echocardiogram can also determine if the underlying cause of the enlargement is from hypertrophic cardiomyopathy, alveolar heart disease, dilated cardiomyopathy and heart deformities (congenital heart disease).  In summary, the echocardiogram can establish the diagnosis of the enlarged heart and provide useful information about and heart muscle function. This test often requires referral to a specialist such as a veterinary cardiologist. The experience of a specialist can be vital to determining the underlying cause for the enlargement to provide the best information to guide treatment and understand the prognosis.

Homecare: What You Need to Do at Home

Please see your veterinarian for all routine physical examinations and follow-up testing.  If your cat is diagnosed with an enlarged heart, it is critical to follow your veterinarian’s recommendations for additional testing such as the ones listed above. Chest x-rays and an echocardiogram can be important to determine the underlying cause for the enlarged heart which will help determine the best treatment options and help you understand the prognosis.  Referral to a board-certified veterinary cardiologist is often the best option to optimize your cats care.

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