Heart Disease Caused by Scarring of the Heart Muscles in Cats


PetMD Editorial

Published Mar. 23, 2009

Restrictive Cardiomyopathy in Cats

A cat's heart is composed of four chambers: the top two chambers are the left and right atria and the bottom two chambers are the left and right ventricles. The valves of the heart are located between the left atrium and the left ventricle (the mitral valve), between the right atrium and the right ventricle (the tricuspid valve), from the left ventricle to the aorta (the main artery of the body, the valve of which is the aortic valve), and between the right ventricle to the main pulmonary artery (the pulmonary, or lung valve).


Cardiomyopathy is the medical term for disease of the heart muscle. Restrictive cardiomyopathy is a disease in which the muscle is stiff and does not expand, such that blood cannot fill the ventricles normally. Restrictive cardiomyopathy in cats is characterized by abnormal filling of the chambers of the heart (known as diastolic dysfunction), severe atrial enlargement, normal left ventricular wall thickness and variable abnormal pumping of the heart (known as systolic dysfunction). Scar tissue of the heart muscle layer may be present. Other heart-muscle disorders, including inflammatory or immune-mediated diseases, may also be present.


Symptoms and Types


  • Lethargy
  • Poor appetite and weight loss
  • Fainting
  • Impaired movement or paralysis
  • Some cats are asymptomatic
  • Difficult breathing
  • Fast breathing
  • Open mouth breathing
  • Pale mucous membranes
  • Abdominal distention




  • Unknown
  • Suspected:
    • Inflammation of the heart muscle
    • Inflammation of the heart muscle and inner lining of the heart
    • Parasites in the heart
    • Thickening of the heart muscle with a heart attack
    • Diffuse small vessel disease and other causes of inadequate oxygen to the heart




Your veterinarian will conduct a complete physical exam with a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis to rule out other causes of disease. will need to give a thorough history of your cat's health, onset of symptoms, and possible incidents that might have precipitated this condition.


Your veterinarian will also order an electrocardiogram to evaluate the electrical conductivity of the heart’s beat for abnormalities. X-rays and an echocardiogram are essential in assessing heart disease and its consequences. X-rays of the lungs should also be taken to check for fluid accumulation.






If your cat is mildly symptomatic or asymptomatic it can be treated on an outpatient basis. Patients with acute, severe congestive heart failure should be hospitalized for emergency care, and patients with severe breathing difficulty will receive oxygen. Low-sodium fluids may be administered cautiously if dehydration occurs, and a heating pad may be necessary for hypothermic patients. Any life-threatening fluid in the chest cavity will need to be reduced. At home, you will need to maintain a low-stress environment to decrease anxiety for your cat. An enclosed space, such as a room, or if necessary, cage rest, will be best for your cat during its recovery. Keeping activity to a minimum is essential for healing. Protecting your cat from active children, guests, and other pets will help in its recovery as well. If your cat is having trouble eating, hand feeding should be employed. Ask your veterinarian for guidance when choosing which foods will best during the recovery period. If your cat refuses to eat, you may need to have nutrition given intravenously.


Living and Management


Your veterinarian will schedule follow-up appointments as necessary to assess your cat’s response to treatment and to assess resolution of swelling and fluid retention. Bloodwork, x-rays and an electrocardiogram should be repeated at each visit. Contact your veterinarian immediately if your cat shows signs of trouble breathing, exercise intolerance or weakness.

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