Hypertrophic Cardiomyopathy (HCM) in Cats: What You Need to Know

Hypertrophic Cardiomyopathy (HCM) in Cats: What You Need to Know

Hypertrophic Cardiomyopathy (HCM) is the most common heart disease in cats, affecting their heart muscle and leading to severe complications. But why does it occur, which cats are at risk, and how can it be diagnosed? Let’s explore everything cat owners need to know about HCM in cats to ensure their feline friends receive proper care.

What Is Hypertrophic Cardiomyopathy?

Cardiomyopathy refers to any disease of the heart muscle. Among the various types of heart disease in cats, hypertrophic cardiomyopathy (HCM) is the most prevalent. As the name suggests, it involves abnormal thickening of the left ventricle, which is responsible for pumping blood throughout the body. If no underlying cause—such as high blood pressure or hyperthyroidism—is identified, then the condition is classified as primary HCM.

What Causes Hypertrophic Cardiomyopathy in Cats?

The exact cause of HCM in cats remains unclear, but genetic factors play a significant role. Certain purebred cats have a higher risk of developing hypertrophic cardiomyopathy due to genetic mutations. Breeds most susceptible to feline HCM include:

• Maine Coon
• Ragdoll
• British Shorthair
• American Shorthair
• Sphynx
• Persian (Exotic Shorthair)

Any purebred cat has a potential risk of developing hereditary HCM due to its genetic background.

Which Cats Are More Prone to HCM?

HCM in cats can occur at any age, with clinical signs appearing anywhere between 6 months to 16 years old. However, the average age of diagnosis is between 5.5 and 6.5 years.

Research has shown that male cats are significantly more likely to develop hypertrophic cardiomyopathy than females, with middle-aged male cats being the most affected group.

Symptoms of Hypertrophic Cardiomyopathy in Cats

One of the biggest challenges with HCM in cats is that many affected cats show no symptoms until the disease has reached an advanced stage. That’s why routine echocardiography (heart ultrasound) is crucial for early detection.

As the condition progresses, some clinical symptoms may become noticeable, including:

• Rapid breathing or shortness of breath (even when at rest)
• Difficulty breathing
• Sudden limb paralysis
• Lethargy or weakness
• Collapse or fainting episodes

These symptoms are typically linked to heart failure, fluid buildup in the lungs (pulmonary edema), pleural effusion, or arterial thromboembolism, which can be life-threatening. In some cases, sudden death in cats may be the first and only sign of HCM.

How Is Hypertrophic Cardiomyopathy Diagnosed?

If a veterinarian detects a heart murmur in cats or any other abnormal findings during a physical exam, they will recommend further diagnostic tests to confirm HCM in cats and rule out other potential causes.

1. Blood Tests

Blood tests assess thyroid function, kidney health, and overall condition to rule out secondary causes such as hyperthyroidism.

2. Chest X-rays

X-rays help evaluate heart size, lung conditions, and any signs of fluid buildup.

3. Blood Pressure Measurement

High blood pressure (hypertension) can contribute to heart disease in cats, so measuring arterial blood pressure is essential.

4. Electrocardiogram (ECG)

An ECG for cats measures heart electrical activity and detects abnormal heart rhythms caused by HCM.

5. Echocardiography (Heart Ultrasound) – The Gold Standard

A heart ultrasound for cats provides detailed imaging of the heart’s chambers, valves, muscle walls, and blood flow. Veterinary cardiologists use this test to make a definitive HCM diagnosis.

Key ultrasound findings in hypertrophic cardiomyopathy include:

• Thickened heart muscle (left ventricle, interventricular septum, or papillary muscles)
• Decreased left ventricular cavity size
• Mitral valve regurgitation
• Left atrial enlargement, sometimes with thrombus formation (blood clots)

If the thickened muscle is obstructing blood flow from the left ventricle, it is classified as obstructive hypertrophic cardiomyopathy (HOCM). This condition increases the risk of heart failure and blood clots in cats.

Conclusion

Hypertrophic cardiomyopathy in cats is an irreversible, genetically driven heart disease with no proven prevention methods. The best way to protect your feline companion is through early detection, routine heart screenings, and proactive management.

Regular veterinary checkups and heart ultrasounds are the most effective tools in preventing HCM-related complications and extending your cat’s lifespan. If you own a purebred cat or a breed predisposed to HCM, consider scheduling a heart checkup as early as possible.

📌 Stay informed and protect your cat’s heart health!

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