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Endocardiosis (Degenerative Changes of Heart Valves) in Dogs

Occurrence: common
Location of illness: Chest

Author: Dr. med. vet. Gisa Löwe | Last modified: 06.11.2025

Endocardiosis, also known as degenerative mitral valve disease, is a common heart disease in dogs characterized by progressiveProgressive describes a condition or disease that worsens over time. This term is often used to characterize the course of an illness that causes increasingly severe symptoms or damage. degenerative changes in the heart valves, especially the mitral valve.

The most important facts at a glance

Endocardiosis is a common heart disease in dogs that primarily affects the mitral valve. This valve normally prevents the backflow of blood in the heart. In endocardiosis, the valve thickens and deforms, leading to incomplete closure and backflow. The exact causes are not fully known, but genetic factors, age, and hormonal influences play a role. Certain breeds, such as Cavalier King Charles Spaniels, are particularly susceptible. The disease usually develops over years and can be accelerated by mechanical stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. and possibly metabolicMetabolic refers to metabolism, i.e. the entirety of chemical processes that take place in a living organism to enable life processes. Metabolic disorders can cause a variety of Diseases in Dogs and cats. disorders.

Symptoms include heart murmurs, increased respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. rate, and cough. In severe cases, ascitesAscites refers to the accumulation of free fluid in the abdominal cavity, which can lead to visible abdominal distension. It can be caused by various diseases, including liver disease, cancer, or heart failure. and respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress may occur. 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 examinations, 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 possibly blood tests. A cure is not possible, but medications such as 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. and ACE inhibitors can relieve symptoms and slow 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.. Surgical interventions are rare because they are complex and costly.

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 the severity of the disease and response to treatment. Early detection and 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. can prolong the dog’s life. Regular veterinary check-ups and a healthy lifestyle are important for preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring.. Research focuses on genetic studies and new treatment approaches to improve the quality of life of affected dogs.

Causes

Endocardiosis primarily affects the mitral valve, which lies between the left atriumThe atrium (plural: atria) is one of the two upper chambers in the heart that receive blood from the body (right atrium) or from the lungs (left atrium). and 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.. This valve plays a crucial role in the circulatory system by preventing the backflow of blood into the left atriumThe atrium (plural: atria) is one of the two upper chambers in the heart that receive blood from the body (right atrium) or from the lungs (left atrium). during contraction 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.. In endocardiosis, the valves thicken and become deformed, leading to incomplete closure and thus backflow of blood.

The exact causes of endocardiosis are not yet fully understood, but genetic factors play a significant role. Certain breeds, such as Cavalier King Charles Spaniels, are particularly susceptible. In addition, hormonal influences and aging processes also appear to contribute to the development of the disease.

Endocardiosis usually develops over years. As the dog ages, the risk of the heart valves showing degenerative changes increases. These changes can be accelerated by mechanical stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. on the valves. It is suspected that metabolicMetabolic refers to metabolism, i.e. the entirety of chemical processes that take place in a living organism to enable life processes. Metabolic disorders can cause a variety of Diseases in Dogs and cats. disorders and inflammatory processes may also play a role.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

An early sign of endocardiosis is often a heart murmur that the veterinarian can detect during a routine examination. This murmur is caused by the turbulent blood flow caused by the incompletely closing mitral valve.

As the disease progresses, symptoms such as cough, respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, and reduced exercise tolerance may occur. These symptoms result from the accumulation of fluid in the lungs, a condition known as pulmonaryPulmonary refers to the lungs or the respiratory system. Pulmonary diseases in dogs and cats include conditions such as Pneumonia, asthma, and pulmonary hypertension. edemaAn edema is a buildup of fluid in the body’s tissues, leading to Swelling. Edema can be localized or generalized and is often a sign of an underlying condition.. Affected dogs often show an increased respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. rate and need to take more frequent breaks when walking.

In advanced stages, 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. and an enlarged 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. may occur. Dogs with severe endocardiosis may also show signs of heart failure, such as loss of appetite, weight loss, and weakness.

Diagnosis

The 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. of endocardiosis is primarily based on clinical examination and recording of symptoms. A heart murmur detected during auscultationAuscultation is an examination method in which the doctor uses a stethoscope to listen to the sounds in the body, especially in the heart, lungs, and intestines, in order to obtain information about the state of health. is an important indicationIndication refers to a valid reason or rationale for using a specific treatment, medication, or medical procedure. It is based on the diagnosis and the patient's clinical condition.. Further diagnostic measures are necessary to confirm the 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. and assess the severity of the disease.

An electrocardiogramSee ECG. (ECG) can be used to assess 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.. Chest X-rays help to detect enlargement of the heart or fluid accumulation in the lungs. 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., an 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. examination of the heart, is particularly valuable for assessing the structure and function of the heart valves in detail.

In some cases, a blood testA blood test is a laboratory procedure in which blood is drawn and analyzed to obtain information about the body's health. It can include various parameters such as blood sugar, blood count, liver and kidney values. may be performed to assess heart function and detect other underlying conditions. This comprehensive diagnostic approach enables an accurate assessment of the disease and the necessary treatment measures.

Therapy

The treatment of endocardiosis aims to alleviate the 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. There is currently no cure for the disease, but various medications can help support heart function and improve the dog’s quality of life.

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. are often the first choice to remove excess fluid from the body and thus reduce the strain on the heart. ACE inhibitors are also widely used because they dilate blood vessels and lower blood pressure, thereby relieving the heart.

In advanced cases, additional medications such as Digoxin or Pimobendan may be used to increase cardiac contractility and improve cardiac output. Regular adjustment of the medication is necessary to meet the changing needs of the patient.

In rare cases, surgery may be considered, especially in young dogs with severe valve disease. However, such procedures are less common in dogs due to the complexity and cost.

Prognosis and follow-up care

The prognosis for dogs with endocardiosis varies greatly and depends on the severity of the disease and the response to treatment. Many dogs can lead a relatively normal life for years with the right treatment. Regular monitoring and adjustment of 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. are crucial to avoid complications and maintain quality of life.

In the early stages of the disease, 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. can be quite good, especially if the disease is detected and treated early. In advanced endocardiosis, especially if there are signs of heart failure, 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 more guarded. Nevertheless, many dogs can remain relatively stable for extended periods with careful medical care.

Prevention

Specific preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of endocardiosis is not currently possible because the exact causes are not fully understood. Nevertheless, there are measures that can reduce the risk of developing or progressing the disease.

Regular veterinary check-ups are crucial to detect early signs of endocardiosis. A balanced diet and a healthy weight can support the health of the cardiovascular system. In breeds that are susceptible to the disease, genetic counseling can be considered to minimize the risk in breeding.

It is also important to watch for signs of respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress or reduced exercise tolerance and to see a veterinarian immediately if heart problems are suspected. Early 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. and treatment are crucial to maintaining the dog’s quality of life.

Outlook on current research

Endocardiosis, also known as myxomatous mitral valve disease, is one of the most common heart diseases in older dogs, especially small breeds. Research in this area is focused on better understanding the exact causes and mechanisms of this degenerative change in the heart valves. Scientists are investigating genetic predispositions that may lead to an increased risk, with some studies suggesting that certain breeds such as Cavalier King Charles Spaniels are particularly susceptible.

A significant portion of current research focuses on the development of new drug treatment approaches. The goal is to 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 and improve the quality of life of affected dogs. Researchers are investigating the effectiveness of ACE inhibitors, 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., and beta-blockers in the treatment of endocardiosis. In doing so, they are trying to determine the optimal combination and dosage of these drugs in order to achieve the best possible results.

Another exciting aspect of research is the investigation of the role of environmental factors and nutrition in the development of endocardiosis. Some studies suggest that a balanced diet and regular exercise may have a preventive effect, although further research is needed to confirm this theory. Avoiding overweight is often recommended as a preventive measure to reduce the strain on the heart.

The use of advanced imaging technology, such as 3D 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., is another important area of research. These technologies allow for a more detailed examination of the heart valves and can help to make more accurate diagnoses and monitor the effectiveness of treatments. The development of such technologies could revolutionize the way endocardiosis is diagnosed and treated.

Genomic studies aimed at deciphering the genetic basis of endocardiosis have also gained importance. This research could make it possible to identify genetic markers that could contribute to early detection of the disease. In the long term, this could lead to the development of targeted therapies tailored to the specific genetic profiles of affected dogs.

A promising field of research is regenerative medicine. It is being investigated whether stem cells or regenerative therapies can be used to repair or regenerate damaged heart valves. Although this type of treatment is still in the experimental stage, the results to date are promising and could open up new avenues for treating endocardiosis in the future.

In summary, research on endocardiosis in dogs is a dynamic and rapidly evolving field. It encompasses a variety of approaches, from geneticsGenetics is the science of genes, heredity, and the variation of organisms. It studies how genetic information is passed from generation to generation and how it influences the development, appearance, and behavior of living things. to pharmacology to imaging and regenerative medicine. These multidisciplinary efforts aim to gain a more comprehensive understanding of the disease and develop innovative treatment strategies that could significantly improve the lives of dogs with endocardiosis.

Frequently asked questions (FAQs)

What is endocardiosis in dogs? Endocardiosis, also known as myxomatous mitral valve disease, is a degenerative disease of the heart valves that mainly affects older dogs, especially small breeds. The valves that regulate blood flow become thicker and irregular, which can lead to decreased heart function.
What symptoms can occur in a dog with endocardiosis? The most common symptoms include cough, respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, reduced exercise tolerance, lethargy, and in severe cases, fainting spells. Some dogs also show loss of appetite and weight loss.
How is endocardiosis diagnosed? 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 usually made through a combination of a physical examination, listening to the heart with a stethoscopeA stethoscope is a medical instrument used for auscultation, or listening to body sounds, such as heartbeats and lung sounds. It is a fundamental tool in medical diagnostics., and imaging procedures such as X-rays, 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., or 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. to assess the condition of the heart valves.
Is endocardiosis curable? Unfortunately, endocardiosis is not curable. Treatment aims 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. This can be achieved through medication, dietary adjustments, and regular veterinary check-ups.
Can certain breeds be particularly susceptible to endocardiosis? Yes, certain breeds, especially small dogs such as Cavalier King Charles Spaniels, Dachshunds, and Poodles, are genetically more prone to developing this disease. However, it can also occur in larger breeds.
What treatments are available for dogs with endocardiosis? Treatment usually involves medications that help reduce the heart’s workload and control symptoms. These include ACE inhibitors, 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., and beta-blockers. Regular monitoring by the veterinarian is also important.
How can I help my dog with endocardiosis lead a good life? A balanced diet, regular gentle exercise, and strict adherence to the medication prescribed by the veterinarian are crucial. It is also important to minimize stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. for the dog and perform regular veterinary check-ups.
Are there preventive measures against endocardiosis? While the genetic 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. cannot be changed, a healthy weight and a balanced diet can help reduce the risk. Regular veterinary check-ups are also important to detect the disease early.
How does endocardiosis affect a dog’s quality of life? Quality of life can be affected, especially in advanced stages of the disease. However, with the right care and treatment, many dogs can lead a relatively normal life. Monitoring and adjustment of treatment by the veterinarian is crucial.
Can endocardiosis lead to other health problems? Yes, if left untreated, endocardiosis can lead to serious complications such as heart failure. It is therefore important to detect and treat the disease early to avoid 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 maintain the dog’s quality of life.