Heart Disease in Cats
Heart disease in cats is often subtle at first, and many cats hide signs of illness until the condition is advanced. Early detection matters, especially if you notice changes in breathing, energy, appetite, or mobility.
Contact a veterinarian promptly if you suspect heart disease
Heart disease in cats can range from silent to life-threatening. Seek urgent veterinary care if your cat has rapid or labored breathing, open-mouth breathing, collapse, sudden hind-leg weakness or paralysis, severe pain, or blue/pale gums. Cats often hide illness well, so even mild changes in breathing or activity deserve attention.
Symptoms to Watch For
Rapid or labored breathing
An increased resting breathing rate, extra effort to breathe, or open-mouth breathing can be a sign of fluid in or around the lungs.
Lethargy or hiding
Cats with heart disease may sleep more, seem less interactive, or hide more than usual.
Poor appetite or weight loss
A reduced appetite and gradual weight loss can happen as heart disease progresses.
Sudden hind-leg pain or paralysis
A blood clot can lodge near the back legs and cause sudden pain, weakness, or paralysis. This is an emergency.
Collapse or weakness
Fainting, sudden collapse, or marked weakness can occur with serious heart rhythm problems or poor circulation.
Exercise intolerance
Cats may not 'exercise' like dogs, so the clue is often subtle: less jumping, less play, or getting tired more easily.
What Causes Heart Disease
In cats, heart disease most often involves the heart muscle itself, called cardiomyopathy. The most common form is hypertrophic cardiomyopathy (HCM), where the muscular wall of the left ventricle becomes abnormally thick. Other heart problems can include restrictive or unclassified cardiomyopathy, arrhythmias, valve disease, congenital defects present from birth, and less commonly heartworm-associated disease. Some cats develop secondary heart changes related to other conditions such as hyperthyroidism or high blood pressure. In many cases, the underlying cause is not fully known, but genetics appears to play an important role.
- Breed predispositions are reported in Maine Coon, Ragdoll, Sphynx, British Shorthair, American Shorthair, Bengal, Chartreux, Norwegian Forest, Siberian, and Persian cats.
- Middle-aged and older cats are more often diagnosed, though congenital defects can be seen in kittens.
- Hyperthyroidism and systemic hypertension can cause or worsen heart changes and should be ruled out.
- Cats on nutritionally imbalanced diets may rarely develop taurine-responsive dilated cardiomyopathy.
- Obvious symptoms may be absent early, so routine veterinary exams are important.
How It's Diagnosed
Diagnosis usually starts with a physical exam, history, and listening for a murmur, gallop rhythm, or abnormal heart rate, but some affected cats have no obvious findings on exam. Your veterinarian may recommend chest X-rays to look for heart enlargement or fluid in or around the lungs, blood pressure measurement, bloodwork to check for diseases like hyperthyroidism, and sometimes a cardiac biomarker such as NT-proBNP to help identify cats that need more testing. The gold-standard test for most feline cardiomyopathies is an echocardiogram, which is an ultrasound of the heart. An ECG may also be used if an arrhythmia is suspected.
- Physical exam findings can be subtle or absent, especially early in the disease.
- Echocardiography is the definitive test for diagnosing and classifying most feline cardiomyopathies.
- Chest X-rays help assess congestive heart failure and fluid buildup.
- Blood pressure and thyroid testing are important because hypertension and hyperthyroidism can mimic or worsen heart disease.
- Cats may be referred to a veterinary cardiologist for advanced imaging and treatment planning.
Treatment Options
Treatment depends on the type of heart disease, whether your cat has symptoms, and whether complications such as congestive heart failure, arrhythmias, or blood clots are present. There is no single cure for most feline cardiomyopathies, but many cats can be managed for months to years with a tailored plan. Treatment may include medications to slow the heart rate or improve relaxation of the heart, drugs to reduce fluid buildup if heart failure is present, medications intended to reduce the risk of clot formation in selected cats, management of underlying diseases such as hyperthyroidism or high blood pressure, and regular rechecks. Activity is usually self-limited in cats, so home monitoring often focuses more on breathing rate, appetite, comfort, and behavior than on formal exercise restriction.
- Cats with breathing difficulty may need emergency stabilization and oxygen support.
- If fluid has built up around the lungs, veterinary drainage may sometimes be needed.
- Treatment plans vary widely by diagnosis, stage, and complication risk.
- Follow-up imaging and monitoring help adjust care over time.
- Never start or stop heart medications without veterinary guidance.
Living with Heart Disease
Frequently Asked Questions
What is the most common heart disease in cats?
Can a cat have heart disease without obvious symptoms?
What symptoms mean my cat needs emergency care right away?
How do veterinarians diagnose heart disease in cats?
Can heart disease in cats be cured?
Are some cat breeds more likely to develop heart disease?
Disclaimer: The information provided in this article is for educational purposes only and does not constitute veterinary medical advice. Reading this content does not establish a veterinarian-client-patient relationship. Every pet is different — always consult a licensed veterinarian before making decisions about your pet's health, diet, or care. If you'd like personalized guidance, you can talk to one of our vets. If your pet is experiencing a medical emergency, contact your local emergency animal hospital immediately.