Heart diseases in cats

The American Veterinary Medical Association suggests that one in 10 cats across the globe is either born with or develops some form of heart disease in their lifetime. There are a number of different types of heart disease in felines, but all of them present with some kind of abnormal structure or function of the heart’s chambers, valves or surrounding muscle.

Types of heart disease

Cats can develop different types of heart conditions. Each one depends on the cat’s genetics, possible trauma to the heart muscle, or some other kind of influence that causes the cat’s heart health to deteriorate. Cats can have congenital or acquired heart disease.

Congenital heart disease

When a kitten is born with a heart problem, it is called ‘congenital’ and may very well be the result of its parents’ genetics. The heart problem can be in the form of a defective heart valve or a weakness or hole in the ventricle wall that separates the right side from the left side of the heart. Both types of malformations can negatively affect the way blood is pumped by the heart muscle and into the body, which can have a negative impact on health and cause some of the symptoms we’ll look at below.

Congenital problems are built-in and cannot simply be ‘medicated’ away; they may need lifelong treatment and sometimes result early death. Fortunately congenital heart disease is much rarer than acquired heart disease.

Acquired heart disease

Acquired – or adult onset – heart disease occurs in older cats and can be caused by wear-and-tear, injury or infection. The most common type of acquired heart disease is hypertrophic cardiomyopathy. This name directly translates to the thickening (hypertrophy) of the heart (cardio) muscle (myo), which causes the disease (pathy).

Less common acquired types of heart disease include:

  • Restrictive cardiomyopathy – when scar tissue builds up around the heart’s lining and reduces its ability to fill up and pump out the blood;


  • Dilated cardiomyopathy – when the walls of the heart become thin and the heart enlarges, severely disabling its ability to pump

Hypertrophic cardiomyopathy

This is the most common type of acquired heart disease in cats, and even though it’s not congenital, it is thought there may be a hereditary link. This means that certain cats may be genetically predisposed to developing hypertrophic cardiomyopathy (HCM) – either with age, or because of other triggers. The cat breeds that are more likely to develop HCM include Maine coons, ragdolls and American shorthairs. Rest assured, this doesn’t mean that they will; just that they have a higher chance of HCM than other breeds.

What are the symptoms of heart disease in cats?

When cats feel sick, they are very good at hiding their symptoms until the illness is quite severe or they go into hiding – a behaviour from their ancestors’ days in the wild, to protect themselves from predators. However, because of the way the heart functions and the other internal organs that depend on it for their own function, cats with heart disease may show the following symptoms:

  • rapid breathing – fast and shallow

  • laboured breathing – noisy or otherwise heavy

  • shortness of breath

  • fatigue

  • difficulty exercising

  • lack of appetite

  • weight loss

  • fainting/collapsing

  • abdominal swelling

  • coughing

  • sudden paralysis in the hind legs, accompanied by pain (caused by blood clots)

  • kittens may have stunted growth

These symptoms can also show in varying degrees, based on how sick the cat may be. When taken to the vet, the vet may detect a heart murmur and an elevated heartbeat (not the result of stress or discomfort, but as a baseline). If these symptoms are too far progressed, the cat may already be in a state of congestive heart failure, which is when the heart’s function is too poorly and there is fluid build-up around the lungs. The blood clots in the arteries near the hind legs can cause a thromboembolism or ‘saddle thrombus’, which is very painful and paralysing, and only about 40% of cats with this condition will have a good prognosis.

How are heart diseases diagnosed?

If a cat is showing any of the above symptoms, they may not necessarily be a sign of hypertrophic cardiomyopathy, but they are distressing enough that the vet should take a look. If the vet suspects HCM, they will perform a cardiac examination. This involves an external physical exam, usually done with a stethoscope to listen for any sounds in the heart and lungs that may be out of the ordinary. A non-invasive ultrasound will also give the vet a good inside view of the cat’s heart and lungs – indicating any abnormalities in the blood vessels, heart chamber, valves and the heart muscle.

The vet will then take the cat’s blood pressure and also do a bloodwork analysis to get an idea of the cat’s general health (sometimes heart disease can be a symptom of hyperthyroidism, so if thyroid hormones in the blood are elevated, this is likely the case). X-rays reveal the heart’s size and position in the chest and show the condition of the lungs, while an electrocardiogram (ECG) can show whether the cat has a heart murmur or any abnormal beat, using the electrical activity of the heart.

Can heart disease be treated?

While there is no cure for HCM, and the damage it does to the physical structures of the heart is not reversible, if it is diagnosed early enough the vet may help to manage the symptoms, slow the progression of the disease and to lower the risk of the cardiomyopathy developing into congestive heart failure. Depending on the severity of the symptoms and the progression of the disease, the vet may prescribe medications that will relax the heart muscle, decrease the heart rate and take some pressure off the cat’s heart. They may also prescribe anti-clotting medication to reduce the risk of the cat developing blood clots or a thromboembolism.

Since these medications do make critical changes to the way the cat’s heart functions, it is crucial that cat owners follow the vet’s recommendations on when and how to administer the dosages. Cat owners may need to learn how to monitor their purry friends’ vital signs (like pulse, breathing, etc.), but since each case is different and may be more or less severe, it is best to follow the vet’s advice on each individual case.

What is the prognosis of cats with heart disease?

If the heart disease is caught early enough, the correct monitoring is performed and/or the correct medications are given, the cat may have a good prognosis and go on to live a fairly normal life. Some cats with a slight heart murmur do not show any symptoms for years; some have symptoms that show up immediately and progress rapidly, so that by the time they are diagnosed, their prognosis is poor.

If the heart disease has progressed to congestive heart failure, these patients can live anywhere from another six to 18 months.

Can heart disease be prevented?

As with many disease prevention protocols, the best way to limit the progression of a disease is through early detection or screening. Cat owners should take their cats in for an annual check-up and not wait for any distressing symptoms before they let the vet see their feline friend.

Feeding the cat a good, high-protein diet can reduce the risk of heart disease; balancing healthy diet with enough exercise and keeping the cat’s stress levels down also goes a long way to ensuring optimal heart health.

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