Heart disease in cats encompasses any abnormality in the structure or function of a cat’s heart. Unfortunately, it’s often silent until advanced stages; many cats show no obvious symptoms of heart trouble until a crisis occurs. By the time signs like breathing difficulty or collapse appear, significant heart damage may already be present. This makes understanding feline heart disease and catching subtle clues early especially important for cat owners.
In this comprehensive blog, we’ll explain what heart disease means (versus heart failure), the common types of heart conditions in cats, signs to watch for, how veterinarians diagnose these issues, treatment options, tips for caring for a cat with heart disease, prevention strategies, and frequently asked questions by pet parents.
What Is Heart Disease in Cats?
Heart disease in cats refers to any structural or functional abnormality of the heart. This could involve problems with the heart muscle (cardiomyopathy), the valves, the heart’s electrical conduction system, or blood vessels connected to the heart. A cat can have heart disease without any outward symptoms if the heart is still compensating well. Over time, however, heart disease can progress and begin to impair the heart’s ability to pump blood effectively.
Heart Disease vs. Heart Failure
It’s important to distinguish heart disease from heart failure.
- Heart disease means there is a problem with the heart (like a thickened muscle or leaky valve), but the cat may still show no symptoms.
- Heart failure happens when the disease has progressed so much that the heart can no longer pump blood properly, leading to poor circulation and fluid build-up, often in or around the lungs.
Not all cats with heart disease develop heart failure, but once heart failure occurs, the condition is considered severe.
Congenital vs. Acquired Heart Disease
Heart disease in cats can be congenital (present from birth) or acquired (develops later in life.
- Congenital heart disease is caused by structural defects a kitten is born with, such as malformed valves or small holes between heart chambers. These are relatively rare and can range from severe (leading to early heart failure) to mild defects that a cat can live with fairly normally.
- Acquired heart disease is much more common and usually appears in adult or senior cats. It often affects the heart muscle (cardiomyopathies) and may be caused by genetics, aging, or other conditions such as hyperthyroidism, high blood pressure, anemia, or past nutritional deficiencies. In short, congenital disease is present from birth, while acquired disease develops over time.
Common Heart Conditions in Cats
When we talk about feline heart disease, we’re usually referring to a few common heart conditions. Below are the major types seen in cats:
Hypertrophic Cardiomyopathy (HCM)
The most prevalent cardiac condition in cats is HCM. The main pumping chamber (left ventricle) becomes abnormally thick, so it can’t relax and fill properly. This reduces pumping efficiency and can lead to fluid buildup in or around the lungs and, in some cats, blood clots. HCM is often genetic and seen more in breeds like Maine Coon, Ragdoll, Sphynx, British Shorthair, and Persian, but it can occur in any cat. Many cats show no signs for years and are diagnosed by echocardiogram.
Dilated Cardiomyopathy (DCM)
In DCM, the heart chambers become enlarged, and the muscle walls thin and weak. The heart can’t contract effectively, so blood doesn’t move forward well, and fluid may back up into the lungs. True DCM is now rare because commercial diets contain enough taurine, but it can still be seen in cats on unbalanced or unusual diets. If taurine deficiency is the cause and is corrected early, heart function may improve.
Restrictive Cardiomyopathy (RCM)
With RCM, the heart muscle becomes stiff and can’t relax and fill normally, even if it isn’t very thick or enlarged. The upper chambers (atria) often become enlarged, and affected cats are at risk of heart failure and blood clots, similar to HCM. RCM is usually seen in older cats, and treatment focuses on managing fluid and reducing clot risk.
Other Heart Conditions
- Valve disease: Some older cats develop leaky valves, which can eventually lead to heart enlargement and heart failure.
- Congenital defects: Kittens may be born with defects such as holes between chambers or a persistent vessel (PDA). In some cases, early surgery or catheter procedures can be curative.
- Heartworm disease: Less common in cats than dogs, but even a few worms can cause serious heart and lung issues. Prevention is key in heartworm areas.
- Arrhythmias and secondary changes: Thyroid disease, high blood pressure, infections, or toxins can cause abnormal rhythms or changes in the heart muscle. Treating the underlying condition often helps the heart.
Signs and Symptoms of Heart Disease in Cats
Cats are very good at hiding illness, so heart disease is often advanced by the time clear signs appear. Watching for changes in your cat’s normal behaviour is key.
Early, Subtle Signs
These can look like “just getting older”:
- Less play and activity
- Sleeping more or seeming “lazy”
- Hiding or being less social
- Slightly faster breathing at rest or after play
- Brief open-mouth breathing after exertion (never normal in cats)
- Mild decrease in appetite or occasional vomiting
Any ongoing change from your cat’s usual routine is worth mentioning to your vet, even if it seems small.
More Obvious / Advanced Signs
As heart disease progresses or turns into heart failure, signs become clearer:
- Rapid or laboured breathing at rest (over ~30 breaths per minute)
- Open-mouth breathing or panting is an emergency
- New coughing or wheezing
- Marked lethargy and weakness, reluctance to jump
- Sudden collapse or fainting
- Poor appetite and weight loss
- Swollen belly from fluid buildup
- Very poor exercise tolerance, tiring after minimal activity
If your cat is breathing fast at rest or breathing with an open mouth, seek veterinary care immediately.
Blood Clots (Saddle Thrombus)
A serious complication of heart disease is a blood clot that travels from the heart and lodges where the aorta splits to the back legs (saddle thrombus).
Typical signs include:
- Sudden inability to use one or both back legs
- Intense pain and crying
- Cold, pale back paws
- Rapid or distressed breathing
This is a true emergency. Even with treatment, the prognosis can be guarded, so managing heart disease early and using clot prevention when recommended is very important.
How Heart Disease in Cats Is Diagnosed
If heart disease is suspected (or picked up during a routine check-up), your veterinarian will start with a physical exam, then recommend tests as needed.
Physical Examination
Your vet will:
- Listen to the heart and lungs for murmurs, extra sounds, or abnormal rhythms
- Feel the pulse and check gum colour and refill time
- Assess breathing rate and effort.
- Check for fluid in the abdomen, weight loss, or an enlarged thyroid
Important: some cats with serious heart disease have no murmur, and some healthy cats can have “innocent” murmurs, so the exam is just the first clue.
Key Diagnostic Tests
- Echocardiogram (heart ultrasound): Gold standard. Shows heart muscle thickness, chamber size, and valve function, and helps distinguish HCM, DCM, and other diseases.
- Chest X-rays: Assess heart size and look for fluid in or around the lungs, helping distinguish heart failure from primary lung disease.
- Electrocardiogram (ECG): Used when an arrhythmia is suspected to analyze the heart’s electrical activity.
- Blood pressure measurement: Detects high blood pressure, which can cause or worsen heart disease.
- Blood tests: Check organ function, screen for anemia or kidney disease, measure thyroid levels (T4), and sometimes use cardiac biomarkers like NT-proBNP to support a diagnosis.
In most cases, the process is your vet notices something abnormal on the exam, then runs blood tests and checks blood pressure, followed by an echocardiogram (and X-rays or an ECG if needed). Based on these results, they can determine what type of heart disease your cat has, how severe it is, and which treatment plan is best.
Heart Disease in Cats: Treatment Options
Treatment depends on the type of heart disease and how advanced it is. In most cases, the goal is to manage the condition rather than cure it:
- help the heart work more efficiently
- prevent fluid build-up (heart failure)
- reduce the risk of blood clots
- treat any underlying cause
Medications
Most cats with heart disease will be on one or more daily medications, such as:
- Heart drugs (e.g., beta-blockers, calcium channel blockers, ACE inhibitors, and pimobendan) to help the heart relax or pump more effectively and reduce its workload.
- Diuretics (like furosemide) are used to remove excess fluid from the lungs or chest in congestive heart failure.
- Blood pressure medicines (e.g., amlodipine) if hypertension is present.
- Anti-arrhythmic drugs to control abnormal heart rhythms.
- Blood thinners (like clopidogrel) to help reduce the risk of blood clots in high-risk cats.
These medications don’t cure cardiomyopathy, but they can improve quality of life and extend survival. It’s very important not to change or stop heart medications without your vet’s advice.
Oxygen and Emergency Care
In a crisis (for example, open-mouth breathing or severe difficulty breathing), cats need immediate emergency care, which may include:
- Oxygen therapy
- Injectable diuretics to pull fluid off the lungs quickly
- Thoracocentesis (draining fluid from the chest) if there is a large amount around the lungs
- Sedation and other emergency drugs to stabilize breathing and support blood pressure
The aim is to stabilize the cat, then switch to oral medications once they’re out of danger.
Treating Underlying Conditions
If heart disease is caused or worsened by another problem, treating that issue can greatly help the heart; for example:
- Hyperthyroidism: Treating an overactive thyroid can reverse or improve heart changes.
- High blood pressure: Controlling it reduces strain on the heart.
- Anemia or taurine deficiency: Correcting these can improve heart function (and in taurine-deficiency DCM, sometimes fully).
Whenever an underlying cause is found, fixing it is a key part of treatment.
When Procedures or Surgery Are Used
Most acquired heart diseases in cats (like HCM or DCM) cannot be fixed with surgery. However, some congenital problems and complications may benefit from procedures, such as:
- PDA closure (surgery or catheter-based) in affected kittens
- Balloon procedures for certain narrowed valves (rare in cats)
- Pacemakers for severe rhythm problems (very rare)
- Thoracocentesis/pericardiocentesis to drain fluid around the lungs or heart
For most cats, though, long-term medical management guided by your vet or a cardiologist is the mainstay of care.
Can Heart Disease in Cats Be Prevented?
You cannot change a cat’s genetics, but you can reduce risks and catch problems earlier.
Screening At-Risk Breeds
If you have a breed prone to HCM (e.g., Maine Coon, Ragdoll, British Shorthair, Persian, Sphynx):
- Ask breeders about heart screening and genetic testing on breeding cats.
- Talk to your vet about a baseline echocardiogram in young adulthood, then periodic rechecks if recommended.
- Cats with confirmed HCM should not be bred when possible.
For most cats, regular vet exams (including listening to the heart) remain the main screening tool.
General Health Maintenance
Good general care also supports heart health:
- Regular vet visits: Annual exams (and every 6 months for seniors) help detect murmurs, high blood pressure, hyperthyroidism, and other problems early.
- Healthy weight and diet: Keep your cat lean and feed a balanced, reputable diet that includes adequate taurine. Avoid unbalanced homemade or fad diets unless designed by a veterinary nutritionist.
- Monitor thyroid and blood pressure in seniors: Early treatment of hyperthyroidism or hypertension can prevent or reduce heart damage.
- Heartworm prevention: Use monthly prevention if you live in or travel to a heartworm area, even for indoor cats.
- Avoid toxins/infections: Keep dangerous human medications, toxic plants, and other hazards out of reach, and keep up with general preventive care.
You can’t prevent every case of heart disease, but good routine care and early screening give your cat the best odds.
FAQs About Heart Disease in Cats
- How long can a cat live with heart disease?
It varies widely. Cats with mild, early HCM can live many years, sometimes a normal lifespan. Cats that have already gone into heart failure or had blood clots have a more guarded outlook, often measured in months to a few years, depending on response to treatment and complications. Your vet or cardiologist can give a more specific estimate based on your cat’s tests. - Can heart disease be cured, or only managed?
Most chronic heart diseases like HCM and RCM are managed, not cured. Medications and lifestyle changes aim to slow progression and control symptoms. Some heart problems can improve or resolve if the cause is treated (for example, heart changes from hyperthyroidism or taurine-deficiency DCM, or a congenital PDA that is surgically corrected). - Are some breeds more likely to develop heart problems?
Yes. Breeds like Maine Coon, Ragdoll, Persian, British Shorthair, Chartreux, Sphynx, and some others have higher rates of HCM. Males are affected more often. However, any cat, including domestic shorthairs, can develop heart disease, especially with age or other illnesses. - Is a heart murmur always serious?
Not always. A murmur simply means turbulent blood flow. Some cats have innocent murmurs with no structural heart disease. Others have murmurs due to real problems like HCM or valve disease. The only way to know is with further testing (often an echocardiogram). A murmur is a reason to investigate, not an automatic crisis. - Can a cat have heart disease with no symptoms?
Yes, very often. Many cats with significant heart disease show no outward signs until advanced stages, heart failure, or a blood clot. That’s why routine exams and targeted screening in high-risk cats are so important. - When is heart disease an emergency?
Seek immediate emergency care if you notice:- Rapid, laboured, or open-mouth breathing
- Resting breathing consistently over ~40 breaths per minute
- Sudden collapse or fainting
- Sudden inability to use one or both back legs, especially with crying in pain and cold hind paws
- Extreme lethargy, pale or blue gums, or obvious distress
