WSU Cougar Head Logo Washington State University
Veterinary Teaching Hospital

Heart disease in cats (Hypertrophic Cardiomyopathy)

Veterinary ECG

What is feline hypertrophic cardiomyopathy? 

Feline hypertrophic cardiomyopathy, the most common type of heart disease in cats, causes the heart muscle to thicken and decreases the heart’s efficiency. Some cats show no sign of illness, especially early in the disease, which can lead to congestive heart failure.

What causes feline hypertrophic cardiomyopathy?

The cause of feline hypertrophic cardiomyopathy is unknown, although certain breeds of cats appear to be predisposed. Middle-aged male cats may be more commonly affected.

What are the signs of feline hypertrophic cardiomyopathy?

Signs of feline hypertrophic cardiomyopathy can vary from no symptoms to lethargy and rapid or labored breathing. Other signs can include sudden weakness, collapsing episodes, and sudden death due to disturbances in heart rhythm.

In some cases, signs of left-sided congestive heart failure, including fluid accumulation in the lung, may occur. These signs include lethargy, decreased activity level, rapid and/or labored breathing, and possibly open mouth breathing with excitement or exercise. Sometimes left and right-sided congestive heart failure develops with fluid accumulation inside the chest or abdominal cavity, causing greater respiratory effort and abdominal distention.

Once fluid accumulations have occurred, clinical heart failure is present, and aggressive medical therapy should be sought.

In some cats with a very large heart chamber, a blood clot may form and if it enters the circulation may cause weakness or paralysis (usually of the rear legs).

How is feline hypertrophic cardiomyopathy diagnosed?

A physical examination by a veterinarian may reveal a heart murmur, abnormal heart and lung sounds, or irregularities in heart rhythm that can lead to a suspected diagnosis of the disease. Chest X-rays, electrocardiograms, and echocardiograms are often used to confirm a diagnosis and determine severity.

A routine physical exam and one or more of these tests may be recommended every six months to one year to look for any progression of disease in cats without clinical signs.

How is feline hypertrophic cardiomyopathy treated?

Treatments for feline hypertrophic cardiomyopathy vary depending on the severity of the disease in the patient.

Asymptomatic cats may not need medical therapy, but routine reevaluations will often be recommended. Other cats will need medications to slow the heart rate and promote relaxation of the pumping chambers (ventricles). If arrhythmias or congestive heart failure signs are present, additional medications may be required.

Since this disease can be progressive, medications and dosage may change with time. Therapy is always tailored to the needs of the individual patient.

What should I do if my cat has or is showing symptoms of feline hypertrophic cardiomyopathy?

If your animal is showing symptoms of feline hypertrophic cardiomyopathy, contact your veterinarian or the WSU Veterinary Teaching Hospital at 509-335-0711. If your cat has already been diagnosed with the disease, our cardiology team can help to create the best treatment plan for your pet.


This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.