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The "Silent Killer": Symptoms of Heart Disease in Cats

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Like you, your feline friend has a heart with four chambers: two on the top called atria and two on the bottom called ventricles. Cardiomyopathy, making up two-thirds of all heart conditions diagnosed in cats, typically affects the left ventricle. This condition can lead to blood clots, congestive heart failure, and even sudden death.

Unfortunately, cats in the early stages of cardiomyopathy – and many other feline heart disorders – often do not present any symptoms. Further complicating matters, most cats mask pain very well. The more you learn about heart disease in cats now, the better you can care for your favorite kitty companion throughout their life.

Overview of Heart Disease in Cats

Feline heart disorders fall into two groups: congenital and acquired.

Congenital disorders are present at birth and include defects such as heart valve malformations and holes in the heart. These conditions are extremely rare. As the term implies, acquired disorders develop over a cat's lifespan.

Examples include high blood pressure, feline myocarditis (inflammation of the heart muscle), and feline aortic thromboembolism (FATE), which is the result of blood clots. By far, the most prevalent acquired feline heart disorder is cardiomyopathy.

From the Latin roots cardio ("heart"), myo ("muscle"), and pathy ("disease"), cardiomyopathy refers to any disease where the heart muscle itself is damaged. There are three main types:

  • Hypertrophic cardiomyopathy (HCM): Occurs when the ventricle tissue, typically the left, thickens to the point that it impairs relaxing, pumping, and filling functions.
  • Restrictive cardiomyopathy (RCM): Characterized by a buildup of scar tissue on the inner lining of the heart that reduces filling and pumping efficiency.
  • Dilated cardiomyopathy (DCM): Develops when the muscular walls become too thin, and the heart becomes enlarged, resulting in very weak pumping ability.

HCM is most common, and it often develops with no explanation other than a suspected hereditary link. Underlying causes could include thyroid disease, high blood pressure, and anemia. Certain breeds are predisposed to the condition, including Maine Coons, Persians, Ragdolls, and some American Shorthairs. Like all acquired heart diseases, HCM generally affects middle-aged and senior cats, but any time you observe symptoms in your cat regardless of age, seek veterinary care immediately.

What About Congestive Heart Failure in Cats?

Congestive heart failure can occur if your cat's heart isn't pumping enough blood to other parts of their body, causing fluid to back up in the lungs. In later stages, your cat will show obvious difficulty with breathing due to this excess fluid. If you notice your feline friend in any type of respiratory distress, it's essential that you seek veterinary care right away.

A wide range of medical conditions can develop into feline congestive heart failure, including thyroid disease, high blood pressure, heartworm disease, anemia, tumors, and birth defects. But the leading cause is HCM. In this instance, the ventricle walls become so thick that the heart's functions are severely compromised. This results in a buildup of fluid in the left atrium, which forces fluid back into the lungs.

gray cat resting on a magenta blanket

Vomiting, Depression, Loss of Appetite, and Other Symptoms

Just like with people, heart disease in cats can be the "silent killer." Too often, HCM and congestive heart failure are in the late stages by the time our feline friends finally start showing the clinical signs.

The two most significant symptoms of heart problems in cats are troubled breathing and difficulty walking, particularly weakness or paralysis of the hind legs. The respiratory distress is due to fluid buildup, of course. Watch for rapid, labored, or open-mouthed breathing.

The hind-leg weakness or paralysis is probably the result of a blood clot. With HCM and congestive heart failure, blood clots often form at the base of the aorta, cutting off the blood supply to the hind legs. If you notice either of these cat heart disease symptoms, seek emergency care for your furry loved one.

There are other, less obvious symptoms you can be on the lookout for, too. These symptoms on their own may not indicate any trouble with your kitty's ticker, but always let your veterinarian know if you observe:

  • Vomiting: Cats aren't able to cough the way dogs can, so their respiratory distress may come out through vomiting instead.
  • Depression: Is your kitty less affectionate than usual? Are they suddenly seeking private spaces rather than cuddle time? This could be more than just a mood swing. Thankfully though, there are many treatment options for cat depression.
  • Lethargy: Sure, cats love to nap, but if you notice your furry friend is less playful and way more tired than usual, take note – especially if they seem winded when you try to exercise them. If your cat faints, call your veterinarian right away.
  • Poor circulation: Check for cold extremities, bluish footpads or nail beds, and grayish gums or tongue. Poor circulation is a pretty clear sign of a heart issue that can often go undetected.
  • Loss of appetite: If you haven't changed your cat's food or routine, but their eating habits have varied, or if your cat stops eating altogether, then this could be a warning sign.
  • Change in weight: If your cat begins to gain or lose weight, at a noticeable rate, then this is often an indication that your kitty companion is dealing with a medical issue.
  • Swollen belly: A bloated or distended belly could mean fluid buildup. While abdominal fluid is more common with dogs, it's not unheard of in cats.
  • Restlessness: Restlessness may be a normal trait for your kitty. Just take note if you observe behavior that seems out of the ordinary.


Your veterinarian will probably begin by measuring your pal's blood pressure and taking blood and urine samples to check for anemia and thyroid problems. With heart disorders, you always want to rule out lesser conditions first. Also, since HCM and congestive heart failure are incurable, identifying any underlying contributors can help manage the disease.

Your veterinarian will also listen to your cat's heart with a stethoscope. Heart murmurs, abnormalities in heart rate, and cardiac rhythm disturbances can be early signs of more serious conditions. Your cat may also need special tests, such as a:

  • Radiograph: This is a chest X-ray. It can show changes in the overall size or shape of the heart and can also detect fluid buildup.
  • Electrocardiogram: This test looks at the electrical currents in the heart muscle and shows if there are any abnormalities in cardiac rhythm.
  • Echocardiogram: This procedure is an ultrasound of the heart. It shows how well the heart is functioning, as well as its internal dimensions and wall thickness.

Bengal cat sleeping on a yellow blanket

Treatment Options

With HCM and congestive heart failure, the right treatment plan can help prolong your cat's life and ensure that their time with you is as comfy as possible.

If your cat has severe congestive heart failure, they may need to be hospitalized, receive oxygen treatments, or have their excess fluid drained with a catheter. Once your cat is stable, or if their condition isn't as critical to begin with, your veterinarian will prescribe medications to address their symptoms.

Remember, HCM and congestive heart failure are progressive, so your pal's treatment plan may change over time. Common medications include:

  • Beta-blockers slow the heart rate and reduce the amount of oxygen the heart uses to help improve blood flow
  • Calcium-channel blockers are similar to beta-blockers but also reduce the strength of the heart's contractions to allow for more rest
  • Angiotensin-Converting-Enzyme (ACE) inhibitors help block certain hormones that are stimulated in cats with heart disease
  • Diuretics are used to help remove fluid in congestive heart failure cases
  • Anticoagulants help prevent blood clot formation but require close monitoring as hemorrhaging can occur

Can You Help Prevent Heart Disease in Your Cat?

The most important thing you can do to help protect your cat against heart disease is to schedule regular wellness visits. Most veterinarians want to see young and middle-aged cats annually, and senior cats may need more frequent check-ups if heart disease is a concern.

In terms of diet, amino acid deficiency can lead to HCM, so try giving your feline friend a human-grade, meat-based, low-sodium diet that skips the unnecessary grains and fillers often found in cat food. Regular exercise is important, too, and sometimes gets overlooked with cats.

Finally, try to keep your little buddy's life as stress-free as possible. Make sure your cat always has a quiet, relaxing retreat away from children and other pets, and shower them with extra affection and reassurance any time your regular routine changes.

An ASPCA® Pet Health Insurance plan can help you with eligible costs for covered conditions like surgery expenses for accidents and help provide peace of mind that your pet can receive the care they need. Check out our online resources to learn more about your insurance options and get a free quote today. The information presented in this article is for educational and informational purposes only and does not constitute or substitute for the advice of your veterinarian.

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