What is feline cardiomyopathy?

Cats with cardiomyopathy have disease of the muscle in the pumping chambers of the heart (ventricles). As a result, the ventricles become stiff and unable to fill properly and pump blood to the body and lungs. Cardiomyopathy can affect young and old cats of any breeds.

• Hypertrophic cardiomyopathy (HCM) is the most common form of feline cardiomyopathy, and is characterized by thickening of the ventricles.
• Restrictive cardiomyopathy (RCM) is the second most common form of feline cardiomyopathy, and is characterized by excessive build-up of scar tissue (fibrosis) on the inner lining of the ventricles.
• Unclassified cardiomyopathy (UCM) is feline cardiomyopathy that doesn’t specifically fall into either of the other two categories, but results in similar heart muscle dysfunction.

How does cardiomyopathy affect my cat and what treatments are available?

In the early stages of heart disease, cats show no symptoms. Prognosis is variable in this stage, and many cats live years without significant progression of disease. Some cats will have a heart murmur, extra heart sound (gallop), or irregular heart rhythm detected when listening to their chests with a stethoscope, but other cats have no outward signs of heart disease unless it becomes severe. Diagnosis of feline cardiomyopathy requires an ultrasound (echocardiogram) by a cardiologist. Treatment may be beneficial for some cats in the early stages of disease, while in others serial rechecks will be recommended.

If the disease becomes severe, the back-up of blood may result in fluid accumulation within or around the lungs and cause trouble breathing, loss of appetite, and decreased energy level. This fluid accumulation is congestive heart failure (CHF). There is no cure for heart failure, but medications are used to control the symptoms. On average, cats with CHF due to cardiomyopathy have good quality of life for 6-12 months.

Cats with heart disease may also be at risk for forming blood clots. These clots can cause strokes leading to weakness or trouble moving the back legs. Medications are often prescribed to try to prevent clots. Cats with cardiomyopathy may also be predisposed to irregular heart rhythms that result in fainting or, if severe, sudden death.

What should I monitor at home?

It is important to become familiar with your pet’s normal sleeping respiratory rate. Often, the first indication of development of heart failure is an increase in the breathing rate when sleeping, and early detection of heart failure can help avoid a hospital stay. Your pet’s respiratory rate should be less than 40 breaths per minute when sleeping. However, any consistent or progressive elevation from your pet’s baseline rate should be cause to alert a veterinarian. There are several free iPhone applications (ex. Cardalis) which can help keep track of respiratory rates.