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Heart Disease

Cardiomyopathy is an alteration in the function of the heart muscle. It can occur for several reasons in cats and can take several forms. When the muscle is sufficiently affected that it cannot function properly, heart failure occurs.

Hypertrophic cardiomyopathy, a common form of heart disease in cats, may be caused by a number of factors, including hyperthyroidism, toxins, infections and genetic influences. With this disorder, the heart muscle loses elasticity and becomes thicker, making it hard for the heart to function properly. At the present time, there is not a clear understanding of the mechanism of the disease.


  • Open-mouth breathing; rapid, shallow panting
  • Vomiting
  • Diarrhea
  • Collapse
  • Pale (bluish or white) mucous membranes
  • Inability to use the rear legs
  • Heart murmur

Risk Factors

Cats of any age (3 months to geriatric), breed or sex are susceptible to developing heart disease, though some cats appear to be at higher risk. Heart disease is diagnosed most often in young male cats (1 to 4 years old). There is also a higher incidence within some cat breeds, including Persians, Ragdolls, American Shorthairs and Maine Coons, where a hereditary basis for the disease has been found.


Physical examination is often sufficient for a presumptive diagnosis of cardiomyopathy, but many cats don’t exhibit symptoms early in the disease process. Heart disease is best confirmed with ultrasonagraphy, but X-rays and electrocardiograms can also be helpful. Many affected cats have heart murmurs that are audible on exam, but murmurs can also occur without heart disease. A serious complication of cardiomyopathy is the development of potentially fatal blood clots.


If heart disease is diagnosed early, long-term management is possible through the use of medications.

Aspirin may be used to reduce the possibility of blood clots. Because of the strong possibility of aspirin poisoning in cats, it is extremely important that this be administered under a veterinarian's supervision and at the prescribed dosages. Aspirin therapy has not been as effective as originally hoped, however. Diltiazem is also commonly used to treat feline heart disease, but it doesn’t work in all cats. A number of other drugs, often the same drugs used in humans, are being researched, including atenolol and other beta blockers and N-acetylcysteine, an antioxidant. One group of medications known as ACE (angiotensin-converting enzyme) inhibitors (captopril, enalapril) are often beneficial in the long-term management of heart failure in cats.

Diuretics are also helpful in many cats, especially when heart failure develops. Other medications to control heart rhythm or to try to increase the muscle strength may be used.


Although there is no cure for heart disease, symptoms can often be controlled successfully with proper treatment. With early diagnosis and treatment, most cats will have a good prognosis.

Current Research

Click here to find out about Morris Animal Foundation–funded research into feline heart disease.

Morris Animal Foundation (MAF) urges pet owners not to implement any suggestions on animal health treatments without prior consultation with a licensed veterinarian. If your pet is experiencing health issues, contact your veterinarian. MAF does not endorse any of the medical treatments described in these articles. The Foundation funds research to enhance medical options available to veterinary professionals and their patients.