Heart disease is increasingly common in cats probably because their average life expectancy has increased due to improved veterinary care. Some heart defects may be present from birth but only show symptoms as the cat gets older. The most common heart disease which develops later in life is hypertrophic cardiomyopathy.

What is cardiomyopathy?

The cat's heart, like that of humans, is a muscular pump with four separate chambers - the right side sends blood to the lungs where it picks up oxygen and the left side receives blood from the lungs and pumps it around the rest of the body. In hypertrophic cardiomyopathy, the heart muscle becomes abnormally thick which prevents the heart from working properly and reduces the amount of blood flowing through it. Another form of the disease is caused by stretching of the heart muscle. This is often seen in cats whose diet has insufficient amounts of a chemical called taurine. However, this disease is much less common now because pet food manufacturers add extra taurine to their products.

What causes the hypertrophic cardiomyopathy?

Older cats with diseases of the thyroid gland or kidneys may develop it. However, it can also occur in otherwise healthy animals and the exact cause is often unknown. It is more common in certain breeds eg Persians, which suggests that it may be inherited in some cases.

What are the signs of heart disease?

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Cats are usually good at concealing ill health and there may be no evidence of any problems until the condition is very advanced. Many of the effects of heart disease are similar to those which occur naturally as your cat gets older - poor appetite, low energy with reduced activity and longer rest periods. Your cat's tongue may turn bluish red as a result of oxygen starvation. Panting, weight loss, restlessness, coughing, fainting and swelling of parts of the body because of water retention may also be seen.

What are the long-term consequences of heart disease?

Heart disease causes increased blood pressure (hypertension) which may cause blood vessels to burst. If the blood vessels in the eye are affected your cat may go blind. Blood clots may form and these can escape into the circulation and block major arteries. If the clot blocks the vessel taking blood to the hind legs it may cause sudden paralysis. This condition is very painful and cats may be found outside, unable to walk and very distressed - the signs are frequently misinterpreted as being the result of a traffic accident. If your cat is found like this it needs emergency veterinary treatment.

What tests are carried out to confirm heart disease?

When listening with a stethoscope your vet can hear changes in the heart sounds, a 'heart murmur'. X-rays will often show that the heart is enlarged or abnormally shaped. Ultrasound scans allow measurements to be made of the heart muscle to see if it is too thick or has become stretched. An electrocardiogram (ECG) records the electrical activity that causes the heart muscle to beat and in cardiomyopathy the heart may have an abnormal or irregular beat.

How is heart disease treated?

If the disease is diagnosed early enough long term medication and other measures can slow the disease down but will not stop it. Possible treatments are:

• Changes to your cat's lifestyle to eliminate stress.
• Drugs to improve the strength of the heartbeat while others help get rid of the excessive fluid that can accumulate in your cat's chest and interfere with its breathing.
• Aspirin may be prescribed (as in human heart disease patients) to stop the formation of blood clots. This drug can be dangerous in cats and the dose has to be carefully controlled. A single dose of aspirin may last as long as three days in your cat (not three hours as in people). NEVER give medication to your cat unless it has been prescribed by your vet.
• Treating (underlying thyroid gland disease, if present) can actually repair the damage to the heart muscle.
• Reduced salt diet to water retention. Special diets for cats with heart disease can be supplied by your vet.

How long will my cat live?

It is difficult to predict how long your cat will live if it has heart disease or how good its quality of life will be. A lot depends on how far the disease has progressed. On average it is likely that your cat will survive for about six months after diagnosis but the time may vary between a few weeks and several years.

Related Factsheets:
Hyperthyroidism - disease and treatment
Samples - how they help your vet
X-rays and ultrasound

If you want any other information on health issues concerning your cat please contact your veterinary surgeon who will be happy to advise you.