February is American Heart Month—a time set aside to raise awareness of heart disease and how people can prevent it. But did you know that people aren’t the only ones affected by heart conditions? Our feline friends are also at risk and, without the proper diagnosis and treatment, their lives can be drastically shortened by this silent killer. How do we promote healthy feline hearts?
Today, we'll cover everything you need to know about hypertrophic cardiomyopathy, a frequently diagnosed heart condition in cats.
What is hypertrophic cardiomyopathy in cats?
Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, characterized by an abnormal thickening of the heart muscle, specifically the left ventricle. This thickening makes it harder for the heart to pump blood efficiently, potentially leading to heart failure, blood clots, or sudden death.
HCM can be mild and asymptomatic in some cats or severe and life-threatening in others. Unlike in humans, where high blood pressure or other underlying conditions often cause heart muscle thickening, feline HCM is often genetic.
Likelihood of HCM in cats
HCM is the most frequently diagnosed heart condition in cats, affecting an estimated 10-15% of cats.
However, its true prevalence may be higher since many cats with mild cases remain undiagnosed. HCM can develop in cats of any age but is most often detected in middle-aged to senior cats.
Because HCM often progresses slowly and can remain asymptomatic for years, many cases go unnoticed until the disease reaches an advanced stage or leads to complications such as congestive heart failure or blood clots.
Cat breeds predisposed to HCM
While any cat can develop HCM, certain breeds are more genetically predisposed to the condition, including:
- Maine Coon – The Maine Coon is one of the most well-known breeds affected by HCM; the condition is even informally referred to as “Maine Coon heart disease.” A specific gene mutation (MYBPC3) has been linked to the disease in this breed.
- Ragdoll – Like the Maine Coon, Ragdoll cats have a genetic mutation associated with HCM.
- British Shorthair – Studies suggest British Shorthair cats are more prone to developing HCM compared to the general cat population.
- Sphynx – Though not as commonly associated with HCM as other breeds, there is evidence that Sphynx cats may have a higher risk.
- Persian, Chartreux, and Norwegian Forest cats – These breeds have also been reported to develop HCM at higher rates than mixed breed cats.
Although genetics play a significant role, HCM can also develop in Domestic Shorthair and Domestic Longhair cats with no known family history of the disease.
Hypertrophic cardiomyopathy symptoms in cats
HCM can be a silent disease for years before symptoms appear. When symptoms do develop, they can vary depending on disease severity and complications. Often, signs aren’t noticed until heart failure has occurred.
Some common signs of HCM progressing to heart failure include:
- Labored or open-mouth breathing (dyspnea) – Caused by congestive heart failure when the heart struggles to pump blood effectively.
- Increased respiratory rate – One of the earliest signs, often due to fluid buildup in the lungs.
- Lethargy and weakness – Affected cats may become less active and tire easily.
- Loss of appetite – Cats may eat less due to discomfort or fluid accumulation.
- Heart murmur or gallop rhythm – Often detected during routine veterinary exams. However, it’s not always present in cats with HCM.
- Sudden collapse or hind leg paralysis – This can occur if a blood clot (aortic thromboembolism) forms and blocks blood flow to the legs, a severe, life-threatening, and painful complication.
Because cats are experts at masking illness, many cases of HCM go unnoticed until the disease is advanced or a medical emergency arises.
Diagnosis of HCM
HCM is diagnosed using a combination of clinical signs, physical exams, and specialized tests:
- Physical examination – A veterinarian may detect a heart murmur, irregular heart rhythm, or abnormal lung sounds during a routine checkup.
- Echocardiogram (ultrasound of the heart) – The gold standard for diagnosing HCM, an echocardiogram assesses heart muscle thickness and function. This is often done at a veterinary specialty center.
- X-rays (radiographs) – Can sometimes show heart enlargement or fluid buildup in the lungs.
- Electrocardiogram (ECG) – Evaluates heart rhythm and electrical activity, though it's less commonly used for HCM diagnosis.
- Blood tests (proBNP test) – A biomarker test that helps assess heart stress and function.
- Genetic testing – Available for some breeds, particularly Maine Coons and Ragdolls, to identify mutations linked to HCM.
Hypertrophic cardiomyopathy in cats treatment
There is no cure for HCM, but treatment focuses on managing symptoms, reducing complications, and improving quality of life. Treatment may include:
- Beta-blockers – Slow heart rate and reduce heart muscle strain.
- Calcium channel blockers – Help relax the heart muscle and improve function.
- ACE inhibitors – Lower blood pressure and reduce heart workload.
- Diuretics – Remove excess fluid in cases of congestive heart failure.
- Anticoagulants – Reduce the risk of blood clots.
- Nutritional support (taurine supplementation) – While not a treatment for HCM, ensuring adequate taurine intake is vital for overall heart health.
Cats with mild HCM may not require immediate treatment but should be monitored closely with regular veterinary checkups.
HCM prognosis
The prognosis for cats with HCM varies widely based on disease severity, age at diagnosis, and the presence of complications.
Many cats with mild HCM live normal lifespans with proper monitoring, while others with severe disease may experience heart failure, blood clots, or sudden death.
Cats diagnosed early and managed appropriately can live for several years, but those with advanced disease or complications often have a shortened lifespan. Regular veterinary follow-ups and medication adjustments are crucial to maintaining stability and quality of life.
Preventing hypertrophic cardiomyopathy in cats
Since HCM is primarily genetic, prevention focuses on responsible breeding practices:
- Genetic testing – Breeders of at-risk breeds should screen cats for known HCM-associated mutations.
- Screening programs – Regular echocardiograms for breeding cats can help identify affected individuals before they pass on the condition.
- Avoid breeding affected cats – Even if symptoms are mild, breeding cats with HCM increases the risk of passing the disease to offspring.
For cat owners, early detection through regular veterinary checkups is the best way to manage and slow disease progression.
Other types of cardiomyopathy in cats
While HCM is the most common form of feline heart disease, other types of cardiomyopathy exist:
- Dilated cardiomyopathy (DCM) – A condition where the heart muscle becomes thin and weak, leading to poor heart function. Once common due to taurine deficiency, DCM is now rare with modern cat diets.
- Restrictive cardiomyopathy (RCM) – The heart muscle becomes stiff and less elastic, impairing blood flow. This condition can resemble HCM but has a different underlying cause.
Final thoughts
Hypertrophic cardiomyopathy is a serious but sometimes manageable heart condition in cats. With early detection, careful monitoring, and appropriate treatment, some cats with HCM can continue to live comfortable lives. Understanding the signs, risk factors, and management options is key to providing the best possible care for our cat companions.
A previous version of this article was written by Kristen Levine Pet Living.
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