Home » Diseases » In dogs » Hypertrophic Cardiomyopathy (Heart Disease Due to Thickening of the Heart Muscle)

Hypertrophic Cardiomyopathy (Heart Disease Due to Thickening of the Heart Muscle) in Dogs

Occurrence: common
Location of disease: Chest

Author: Dr. med. vet. Gisa Löwe | Last modified: 17.02.2026

When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

If the condition worsens / symptoms persist, consult a veterinarian.

Definition

Hypertrophic Cardiomyopathy (HCM) is a heart disease in dogs characterized by a thickening of the heart muscle, especially of the left ventricleA ventricle is one of the two lower chambers of the heart that pump blood into the arteries. The right ventricle pumps blood to the lungs, while the left ventricle pumps blood throughout the body., which can impair the normal function of the heart.

The most important facts at a glance

Hypertrophic cardiomyopathy (HCM) in dogs is a heart disease in which the heart muscle is thickened, impairing the heart’s ability to pump blood efficiently. This thickening makes the heart chambers stiffer, making it harder for the heart to fill with blood during the relaxation phase. The causes of HCM are not fully understood, but genetic factors play a major role. Some dog breeds have an inherited predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases., while in other cases the cause is unknown. Symptoms include reduced exercise tolerance, DyspneaDyspnea, also known as shortness of breath, is the subjective feeling of breathlessness or difficulty breathing. It can be a symptom of a variety of conditions, including heart disease, lung disease, and anemia. (labored breathing), and Cough. DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made through clinical examination, cardiac ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow., and sometimes genetic testing. Treatment aims to relieve symptoms and improve quality of life, as a cure is not possible. Medications such as a beta blockerBeta blockers are a class of medications used to lower blood pressure, treat cardiac arrhythmia, and reduce the heart's workload. They work by reducing the effect of epinephrine on the heart. and diureticsDiuretics are medications that increase urine production in the kidneys to rid the body of excess salt and water. They are often used to treat high blood pressure, heart failure, and certain types of edema. may be used. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. varies depending on disease severity and response to treatment. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is limited, but responsible breeding practices and regular veterinary check-ups can help detect early signs. Research focuses on genetic studies and new treatment methods, including investigating nutrition and regenerative medicine.

Causes

HCM in dogs is a condition that impairs the heart’s ability to pump blood efficiently. The thickening of the heart muscle causes the ventricles to become stiffer, making it difficult for the heart to fill with blood during the diastolic phase, i.e., the relaxation phase of the heart muscle. This thickening can also affect the heart valves and the blood vessels that supply the heart itself.

The exact causes of HCM in dogs are not fully understood, but genetic factors are believed to play a major role. In some dog breeds, as in cats, there is an inherited predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases. to developing this condition. In other cases, the cause may be idiopathicIdiopathic refers to a condition or disease for which the cause is unknown. It is used when no clear external cause or underlying disease can be identified as an explanation for the symptoms., meaning it is unknown.

In addition to genetic factors, environmental factors and secondary diseases could contribute to the development of HCM. Some studies suggest that hormonal disorders, such as hyperthyroidism, may also be associated with heart muscle thickening. However, this is less common in dogs than in cats.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

Dogs with HCM can show a range of symptoms that are often subtle and hard to recognize. Common symptoms include DyspneaDyspnea, also known as shortness of breath, is the subjective feeling of breathlessness or difficulty breathing. It can be a symptom of a variety of conditions, including heart disease, lung disease, and anemia. (labored breathing), Cough, reduced exercise tolerance, or sudden weakness. These symptoms result from the heart’s reduced ability to pump blood efficiently, which can lead to fluid accumulation in the lungs or chest cavity.

In some cases, Cardiac arrhythmiaAn arrhythmia is a heart rhythm disorder in which the heart beats irregularly, either too fast (tachycardia), too slow (bradycardia), or with an irregular pattern. Arrhythmias can be harmless or a sign of serious heart problems. can occur, presenting as an irregular heartbeat. These can be serious and may lead to syncopeA syncope is a sudden, temporary loss of consciousness, usually due to a brief drop in blood pressure and reduced blood flow to the brain. Syncopes can be triggered by various factors, including stress or heart problems. (brief loss of consciousness).

Another possible, but less common, symptom is ascites—fluid buildup in the abdomen—which can be caused by congestion in the venous circulation. Some dogs also show signs of Restlessness or behavioral changes, which may indicate discomfort or Pain.

Diagnosis

Diagnosing hypertrophic cardiomyopathy in dogs requires a combination of clinical examination, imaging, and sometimes genetic testing. The vet will first take a thorough medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits. and examine the dog for symptoms that could indicate heart problems.

An important diagnostic tool is echocardiographyEchocardiography is an ultrasound examination of the heart that assesses the structure and function of the heart valves and chambers. It can provide information about heart size, pumping function, and the presence of heart disease. (cardiac ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow.), which provides a detailed view of the heart chambers and valves. EchocardiographyEchocardiography is an ultrasound examination of the heart that assesses the structure and function of the heart valves and chambers. It can provide information about heart size, pumping function, and the presence of heart disease. allows the vet to assess thickening of the heart muscle as well as heart function.

In addition, chest X-rays may be taken to detect signs of fluid buildup or changes in heart size. An ECG (electrocardiogram)An electrocardiogram is a recording of the electrical activity of the heart over time. It is used to diagnose cardiac arrhythmia, damage to the heart muscle, and other heart problems. can be used to identify Cardiac arrhythmiaAn arrhythmia is a heart rhythm disorder in which the heart beats irregularly, either too fast (tachycardia), too slow (bradycardia), or with an irregular pattern. Arrhythmias can be harmless or a sign of serious heart problems..

In some cases, a genetic test may be considered, especially if an inherited form of HCM is suspected. These tests can help identify genetic mutations associated with the disease.

Therapy

The treatment of HCM in dogs aims to alleviate the symptoms and improve the animal’s quality of life, as a cure for the disease is not possible. Medications can be used to support heart function and control symptoms.

A beta blockerBeta blockers are a class of medications used to lower blood pressure, treat cardiac arrhythmia, and reduce the heart's workload. They work by reducing the effect of epinephrine on the heart. or calcium channel blockerCalcium channel blockers are medications that slow the flow of calcium ions into heart muscle and blood vessel cells, leading to blood vessel dilation and a reduction in blood pressure. They are used in dogs and cats to treat high blood pressure and certain heart conditions. may be prescribed to lower heart rate and regulate blood pressure, which can reduce strain on the heart. DiureticsDiuretics are medications that increase urine production in the kidneys to rid the body of excess salt and water. They are often used to treat high blood pressure, heart failure, and certain types of edema. can help remove excess fluid from the body, reducing DyspneaDyspnea, also known as shortness of breath, is the subjective feeling of breathlessness or difficulty breathing. It can be a symptom of a variety of conditions, including heart disease, lung disease, and anemia. (labored breathing) and Swelling.

ACE inhibitorACE inhibitors are medications that inhibit angiotensin-converting enzyme, thereby lowering blood pressure. They also have a protective effect on the kidneys. They are used in dogs and cats to treat heart disease, high blood pressure, and certain kidney diseases. can also be useful to reduce strain on the heart and dilate blood vessels. In some cases, treatment for Cardiac arrhythmia may be necessary, which can be achieved with antiarrhythmicAntiarrhythmic medications are substances used to treat and provide prevention of irregular heartbeats. They work by stabilizing the electrical activity of the heart. medications.

It’s important that treatment is tailored to the individual dog, as responses to medication can vary. Regular check-ups with the vet are essential to monitor disease progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. and adjust therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. accordingly.

Prognosis and follow-up care

The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. for dogs with HCM varies greatly and depends on several factors, including the severity of the disease, response to treatment, and the presence of concurrent conditions. In some cases, the disease can remain stable for years, while in others it may progress quickly.

A dog with a mild form of HCM that responds well to treatment can have a relatively normal quality of life. However, in more severe forms of the disease—especially if complications such as Cardiac arrhythmiaAn arrhythmia is a heart rhythm disorder in which the heart beats irregularly, either too fast (tachycardia), too slow (bradycardia), or with an irregular pattern. Arrhythmias can be harmless or a sign of serious heart problems. or heart failure occur—the prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is less favorable.

It is important to always keep the animal’s quality of life in mind and work closely with the veterinarian to ensure the best possible care. In some cases, a serious deterioration of the disease may require a difficult decision about euthanasia to spare the animal unnecessary suffering.

Prevention

Because the exact cause of HCM in dogs is often unknown, specific preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. strategies are limited. In breeds predisposed to HCM, responsible breeding practices can help reduce the risk of passing on genetic predispositions. This includes genetic screening of breeding animals and excluding animals with known genetic mutations from breeding.

Regular veterinary check-ups are crucial to detect early signs of heart problems. A timely diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. can help slow disease progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. and improve the dog’s quality of life. Owners should watch for possible symptoms and consult a vet immediately if heart problems are suspected.

A balanced diet and regular exercise can also contribute to general heart health, although they cannot directly prevent the development of HCM. It is important to keep the dog fit and at a healthy weight to minimize the strain on the heart.

Outlook on current research

Hypertrophic cardiomyopathy (HCM) is a complex condition that occurs less often in dogs than in cats, but is no less significant. Current research focuses on better understanding the genetic basis of this disease in dogs. Genetic studies have shown that HCM often runs in families, meaning there is an inherited component. Researchers are working to identify specific genetic markers associated with the disease to enable earlier and more accurate diagnoses.

Another research focus is the development and improvement of diagnostic techniques. Early detection of HCM is crucial to slow disease progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. and improve the dog’s quality of life. Current studies are examining the effectiveness of advanced imaging methods such as echocardiographyEchocardiography is an ultrasound examination of the heart that assesses the structure and function of the heart valves and chambers. It can provide information about heart size, pumping function, and the presence of heart disease. and magnetic resonance imaging (MRI)Magnetic resonance imaging is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the inside of the body. It is used in veterinary medicine to diagnose diseases of the brain, spine, and other organs. for detailed assessment of heart structure and function.

Treatment options for HCM in dogs are also at the center of research. While current treatments aim to alleviate symptoms and slow the progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of the disease, scientists are investigating new drug approaches that could directly target the underlying causes of the disease. Clinical trials are testing the effectiveness of new drugs that may slow heart muscle growth or improve heart function.

In addition to drug treatment, the role of nutrition in the treatment of HCM is also being investigated. Some studies suggest that certain diets or supplements may affect the risk or progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of the disease. Researchers are evaluating the effects of omega-3 fatty acids and other heart-supporting nutrients on dogs with HCM to develop more precise nutritional guidelines.

A promising area of research is regenerative medicine. Scientists are investigating the possibility of using stem cells to repair or regenerate damaged heart tissue. Although this research is still in its early stages, it could offer new treatment approaches for dogs with HCM in the long term.

Finally, collaboration between research institutions and veterinarians plays an important role in combating HCM. By combining clinical practice and scientific research, new findings can be integrated more quickly into daily veterinary care, which could lead to better treatment outcomes for dogs with HCM.

The future of HCM research in dogs looks promising. With ongoing studies and advances in veterinary medicine, scientists hope to develop more effective diagnostic and treatment methods soon, significantly improving the lives of affected dogs.

Frequently asked questions (FAQs)

What is hypertrophic cardiomyopathy (HCM) in dogs?

Hypertrophic cardiomyopathy is a heart disease in which the heart muscle becomes thickened. This thickening makes it difficult for the heart to pump blood efficiently, which can lead to various health problems. -

What symptoms occur in dogs with HCM?

The most common symptoms include Dyspnea (labored breathing), Cough, weakness, reduced activity, fainting spells, and in some cases, sudden cardiac death. Some dogs may not show any symptoms until the disease is advanced. -

How is HCM diagnosed in dogs?

Diagnosis is usually made using a combination of physical examination, X-rays, echocardiogram, and sometimes an ECG (electrocardiogram). These tests help assess the structure and function of the heart. -

Is HCM curable in dogs?

HCM is currently not curable, but symptoms can be managed with medication and lifestyle changes. Early diagnosis and treatment can slow disease progression and improve the dog’s quality of life. -

Which dog breeds are most commonly affected by HCM?

While HCM is generally less common in dogs, some breeds such as the Doberman Pinscher, Boxer, and Cavalier King Charles Spaniel may be more susceptible to various forms of heart disease, including HCM. -

What treatment options are available for dogs with HCM?

Treatment may include medications to control heart rate and improve heart function. Diuretics may be used to reduce excess fluid in the body. In severe cases, surgical intervention may be necessary. -

Can dogs with HCM live a normal life?

With the right treatment and regular veterinary monitoring, many dogs with HCM can live a good life. It is important to follow the veterinarian's instructions and have regular check-ups. -

Are there ways to prevent HCM in dogs?

Since HCM is often genetic, there are no sure ways to prevent it. However, early detection in dogs that are at increased risk and regular veterinary monitoring can help detect and treat the disease early. -

Can a dog's diet affect HCM?

Although diet cannot cure HCM, there is evidence that a balanced diet with heart-supporting nutrients can positively influence the life of a dog with HCM. It is advisable to discuss the best dietary options with a veterinarian. -

How important is genetic research for understanding HCM in dogs?

Genetic research is crucial to better understand the causes of HCM and identify potential genetic markers. This could lead to improved diagnostic and treatment strategies in the future.