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Acquired Heart Disease in Cats: HCM, DCM, and Adult-Onset Conditions

Oct 30 • 10 min read

Your cat has never had a health scare in her life. She's five, healthy-looking, eats well, and plays like always. Then, at a routine annual check-up, your vet pauses with the stethoscope on her chest. "I'm hearing something." No symptoms. No warning. Just a sound. This is exactly how most cat heart disease introduces itself, quietly, in an otherwise perfectly normal-looking cat

Acquired heart disease is heart disease that develops later in life, as opposed to congenital defects a cat is born with. It's remarkably common in cats, far more common than in dogs, and the most frequent form, hypertrophic cardiomyopathy (HCM), can be present for years without a single visible sign. Understanding the different types, and what makes each one different, helps you know what questions to ask and what to watch for.

Key Takeaways

Acquired heart disease develops later in a cat's life, unlike congenital defects, which are present from birth.
Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, caused by a thickening of the heart's main pumping chamber, and often has no symptoms until it's advanced.
Dilated cardiomyopathy (DCM) is now rare thanks to taurine being added to commercial cat food since 1987, but it can still occur in cats fed home-cooked, vegetarian, or dog food diets.
Other acquired conditions include restrictive cardiomyopathy, degenerative valve disease, high blood pressure, and rarer causes like infection or fluid around the heart.
Certain breeds, including Maine Coons, Ragdolls, Persians, and Sphynx cats, carry a higher genetic risk for HCM specifically.
Diagnosis relies heavily on echocardiography, since a heart murmur alone doesn't confirm or rule out heart disease, and about a third of HCM cats have no murmur at all.

What Is Acquired Heart Disease in Cats?

Acquired heart disease refers to heart conditions that develop over a cat's lifetime rather than being present at birth, which sets it apart from the congenital heart defects covered in one of our earlier guides. Most acquired heart disease in cats falls under cardiomyopathy, a general term for disease that primarily affects the heart muscle itself.

According to the Merck Veterinary Manual, cardiomyopathies in cats are classified into several types: hypertrophic, dilated, restrictive, arrhythmogenic right ventricular, and unclassified. Beyond cardiomyopathy, cats can also develop degenerative valve disease, infections of the heart lining, fluid buildup around the heart, and high blood pressure, all of which are covered further down.

Hypertrophic Cardiomyopathy (HCM): The Most Common Cat Heart Disease

Illustration comparing a normal cat heart to one affected by hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is, by a wide margin, the most frequently diagnosed heart disease in cats. It happens when the walls of the left ventricle, the heart's main pumping chamber, thicken and become stiff. As the chamber walls thicken, the space inside shrinks, the left atrium enlarges to compensate, and over time this can progress toward heart failure.

What Causes HCM

HCM is caused by an inherited genetic defect, and it runs in families within specific breeds. Cats known to carry a higher genetic risk include Persians, Sphynx, Norwegian Forest Cats, Bengals, Turkish Vans, Maine Coons, Ragdolls, and American and British Shorthairs. It can appear anywhere from 3 months to 17 years of age, though most cats are diagnosed in middle age. Males and females are affected equally often, but males tend to develop more severe disease at a younger age.

Signs of HCM

Here's the genuinely difficult part: many cats with HCM show no signs at all for a long time. When signs do appear, they can include:

Sudden difficulty breathing
Collapse
Weakness or paralysis of the hind limbs, caused by a blood clot lodging where the aorta divides near the hips, known as a saddle thrombus
Sudden death, in some cases, with no prior warning

A vet may hear a heart murmur or an extra "gallop" heart sound during a routine exam, but here's the catch: at least one in three cats with HCM has no murmur at all. This is exactly why a clean stethoscope check doesn't fully rule out HCM, particularly in a higher-risk breed.

Diagnosis and Treatment

X-rays and echocardiography (a heart ultrasound) help confirm HCM and determine how advanced it is. Treatment focuses on controlling signs of heart failure, supporting heart function, and reducing the risk of blood clots, using diuretics, oxygen therapy, calcium-channel blockers, beta-blockers, or ACE inhibitors depending on the individual case. Many mildly affected cats have a genuinely good long-term outlook, while cats who progress to congestive heart failure face a more guarded prognosis. For a deeper look at what heart failure specifically looks like and how it's staged, see our guide on congestive heart failure in cats.

Dilated Cardiomyopathy (DCM) and the Taurine Story

Dilated cardiomyopathy is a disease where the heart muscle progressively loses its ability to contract properly, causing the heart chambers to stretch and enlarge. DCM has a genuinely remarkable backstory: it used to be one of the most common causes of feline heart disease, until 1987, when researchers discovered that most cases were caused by a dietary deficiency of taurine, an amino acid cats cannot make in adequate amounts on their own. Once commercial cat food manufacturers began adding taurine to their formulas, the incidence of DCM in cats dropped dramatically. Today, most DCM cases are not taurine-related and reflect disease of unknown cause instead.

Why This Still Matters for Indian Cat Owners

Illustration showing the importance of a complete, taurine-adequate cat food diet.

Taurine-responsive DCM hasn't disappeared. Merck specifically notes that when it does occur today, it's almost always in cats fed noncommercial diets, including vegetarian diets, baby food, home-cooked meals, or dog food, none of which reliably contain adequate taurine for a cat's needs. This is a genuinely relevant point in Indian households, where vegetarian family diets are common and cats are sometimes fed dal, rice, roti, or milk-based meals rather than a complete, meat-based commercial cat food. If your cat's diet leans heavily on home-cooked or vegetarian food, it's worth a direct conversation with your vet about whether taurine supplementation or a diet switch makes sense, since this is one of the few forms of feline heart disease that's genuinely preventable through diet.

Signs and Outlook

Cats with heart failure from DCM often show extreme difficulty breathing, caused by fluid building up in the lungs or chest cavity, and this respiratory distress can progress rapidly. The outlook for non-taurine-responsive DCM is unfortunately grave: roughly half of affected cats die within two weeks of diagnosis. For taurine-responsive cases, the risk of death is still high in the short term, but cats who can be stabilised long enough for taurine supplementation to take effect, usually two to three weeks, have an excellent long-term outlook.

Other Cardiomyopathy Types

Infographic summarising the main types of acquired heart disease in cats.

Beyond HCM and DCM, a few less common forms round out the cardiomyopathy picture:

Type	Key Feature	Outlook
Restrictive cardiomyopathy (RCM)	Left ventricle becomes stiff without significant muscle thickening; cause unknown	Similar signs to HCM, but generally worse outlook, especially with heart failure
Arrhythmogenic right ventricular cardiomyopathy	Rare; fibrous and fatty tissue replaces normal right ventricle muscle	Generally poor long-term outlook
Unclassified cardiomyopathy	Clear abnormalities on echocardiography that don't fit neatly into other categories	Similar to HCM, but worse outlook in cats with heart failure

Two rarer causes worth knowing by name: atrial standstill, which destroys the muscle wall of the atrium and rarely responds well to treatment, and endocardial fibroelastosis, an inherited condition seen mostly in young Siamese and Burmese cats under six months old, which behaves similarly to DCM.

Degenerative Valve Disease in Cats

Unlike in dogs, where valve disease is extremely common, degenerative valve disease is uncommon in cats. It happens when heart valves, most often the mitral valve, thicken and stop closing properly, letting blood leak backward through the heart. Early on, there are typically no visible signs beyond a possible murmur. As the disease advances, affected cats may become unwilling to lie down normally or develop difficulty breathing. Treatment often isn't started until signs of heart failure appear, and usually involves diuretics and ACE inhibitors, with additional medication added as needed for arrhythmias. Cats can live for years with appropriate, staged treatment.

Other Adult-Onset Heart Conditions to Know

A few rarer conditions round out the picture of acquired feline heart disease:

Infective endocarditis is a rare bacterial infection of the heart valve lining. It can cause fever, weight loss, fatigue, and a murmur, and pieces of infected clot can travel to other organs. Treatment combines heart failure management with antibiotics to clear the underlying infection.

Pericardial disease occurs when fluid builds up around the heart (pericardial effusion), compressing it and interfering with its ability to pump, a condition called cardiac tamponade. This is uncommon in cats and is most often linked to congestive heart failure itself, though cancer and infection are other possible causes. It requires urgent treatment, often including a procedure to drain the fluid directly.

Systemic hypertension (high blood pressure) in cats is usually secondary to another disease, most commonly kidney disease or hyperthyroidism, rather than occurring on its own the way it often does in people. The most noticeable sign can be sudden blindness, since high blood pressure can damage the eyes. Vets typically only check blood pressure in cats who already have kidney disease, hyperthyroidism, or other risk factors, rather than as a routine screen for every healthy cat.

Signs That Should Prompt a Vet Visit

Because so many cats with acquired heart disease look completely normal for a long stretch of time, it's worth knowing the pattern of signs worth acting on:

Difficulty breathing or rapid breathing, especially at rest
Sudden weakness, collapse, or hind-leg paralysis
Reduced activity or reluctance to play
Loss of appetite
Fainting

My Cat Seems Perfectly Healthy. Why Would My Vet Suggest a Heart Check-Up Anyway?

This is one of the more counterintuitive things about feline heart disease: because HCM in particular can develop and progress silently for years, "seems fine" and "has no heart disease" are not the same thing, especially in a higher-risk breed like a Maine Coon or Ragdoll. A vet who hears a murmur, a gallop sound, or simply wants to screen a predisposed breed proactively isn't overreacting; they're catching exactly the kind of disease that tends to announce itself suddenly and seriously if it isn't caught early. If your vet suggests an echocardiogram for a seemingly healthy cat in a higher-risk breed, it's a reasonable and genuinely useful recommendation, not an unnecessary expense.

How Is Acquired Heart Disease Diagnosed?

Physical examination is the starting point, though as covered above, a normal exam doesn't fully rule out heart disease, particularly HCM.

Chest x-rays can show heart size and shape and reveal fluid buildup in or around the lungs, though they don't always give a definitive answer on their own.

Echocardiography (heart ultrasound) is the single most useful test for confirming most forms of acquired heart disease, since it lets a vet directly see the heart's structure, wall thickness, chamber size, and how well it's contracting.

Electrocardiography (ECG) detects arrhythmias, which can develop as heart disease progresses in several of the conditions covered here.

Sleeping respiratory rate monitoring is a genuinely useful, free tool your vet may ask you to use at home: counting your cat's breaths for a minute while she's fully asleep and not purring can flag early fluid buildup in the lungs, often before more obvious symptoms appear.

Treatment and Outlook

Treatment depends entirely on which condition your cat has and how advanced it is, but a few themes run across most of them: diuretics to manage fluid buildup, ACE inhibitors like benazepril to ease the heart's workload, and, for HCM specifically, medications to reduce the risk of dangerous blood clots. Some cats, particularly those with mild HCM caught early, live for years with a genuinely good quality of life. Others, especially cats diagnosed only after reaching congestive heart failure, face a more guarded outlook, which is exactly why routine wellness exams and breed-appropriate screening matter as much as they do.

Can Acquired Heart Disease Be Prevented?

Most forms can't be fully prevented, since conditions like HCM have a genetic basis that diet and lifestyle don't change. But a few genuinely useful steps exist:

Feed a complete, taurine-adequate commercial cat food. As covered above, this has already all but eliminated one entire form of feline heart disease and remains the single most preventable cause on this list.

Ask about screening if you have a higher-risk breed. Maine Coons, Ragdolls, Sphynx cats, Persians, Bengals, Turkish Vans, and British and American Shorthairs all carry elevated genetic risk for HCM specifically, and an earlier or more frequent echocardiogram may be worth discussing with your vet.

Don't skip annual wellness exams, and move to twice-yearly visits once your cat reaches senior age, since a murmur or gallop sound picked up early gives your vet far more room to plan ahead.

Manage underlying conditions like kidney disease and hyperthyroidism promptly, since untreated, these can drive secondary high blood pressure that stresses the heart over time.

FAQ

Can cats live a normal lifespan with acquired heart disease?
Many cats, especially those with mild disease caught early through routine screening, live for years with a good quality of life. Outlook varies significantly by the specific condition and how advanced it was at diagnosis, which is why early detection matters so much.

Is HCM in cats the same as heart disease in humans?
The name is shared with a human condition, but feline HCM is its own distinct disease with different genetics, breed patterns, and treatment approaches. It shouldn't be assumed to behave identically to the human version.

Can indoor-only cats develop acquired heart disease?
Yes. Most acquired heart disease in cats, HCM in particular, is driven by genetics rather than lifestyle or outdoor exposure, so being entirely indoors offers no protection. This is exactly why routine wellness exams matter for indoor cats too.

Does a heart murmur always mean my cat has heart disease?
No. Some murmurs are "innocent," particularly in young, rapidly growing kittens, and have no connection to structural heart disease. At the same time, roughly a third of cats with HCM have no murmur at all, so the presence or absence of a murmur alone isn't a reliable yes-or-no test either way.

How often should a Maine Coon or Ragdoll be screened for heart disease?
There's no single universal answer, since it depends on your individual cat's age, family history, and your vet's clinical judgement, but many vets recommend periodic echocardiograms starting in young adulthood for these higher-risk breeds. It's worth asking your vet directly what screening interval makes sense for your specific cat.