Home » Diseases » In dogs » Hemangiosarcoma of the Heart (Heart Cancer)

Hemangiosarcoma of the Heart (Heart Cancer) in Dogs

Occurrence: very rare
Location of disease: Chest

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

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Urgent see a veterinarian within 24 hours

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

Definition

A cardiac hemangiosarcoma in dogs is a malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. that originates from the blood vessels and typically affects the heart, especially the right 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).. It is an aggressive type of cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. that often leads to sudden health complications.

The most important facts at a glance

Hemangiosarcomas are aggressive tumors in dogs that arise from the cells lining blood vessels. They frequently occur in the heart, but also in organs such as the spleen and liver. These tumors tend to bleed, which can be life-threatening, especially in the heart. The exact causes are unclear, but genetic factors and certain dog breeds such as the German Shepherd, Golden Retriever, and Labrador Retriever are more frequently affected. Possible risk factors include environmental factors and chemical exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats., although concrete evidence is lacking.

Symptoms include respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, 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., weakness, and loss of appetite. Diagnostic methods include physical examinations, 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., and blood tests. In some cases, biopsies are necessary. Treatment depends on the progress of the disease and can include surgical removal, chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells., or palliativePalliative refers to treatments that aim to alleviate the symptoms of a disease without curing the disease itself. Palliative care focuses on improving the quality of life of patients with incurable diseases. 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.. Despite treatment, 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 often poor, with survival times of a few weeks to months.

PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is difficult because the causes are not fully understood. However, regular veterinary examinations and a healthy lifestyle can be helpful. Research focuses on genetic and molecular mechanisms, new treatment methods, and earlier 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. possibilities. Targeted therapies and immunotherapies are being investigated. Personalized treatment approaches and international research collaborations could lead to better outcomes in the future.

Causes

Hemangiosarcomas are tumors that arise from the cells lining blood vessels, known as endothelial cells. These tumors are highly vascularized, meaning they contain many blood vessels, and therefore they tend to bleed easily. The tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. can occur both in the heart itself and in other organs such as the spleen or liver. However, the heart is a particularly vulnerable area, as the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. can lead to life-threatening bleeding there.

The exact causes for the development of hemangiosarcomas are not fully understood. It is believed that genetic factors play a role, as certain dog breeds such as the German Shepherd, Golden Retriever, and Labrador Retriever are more frequently affected. This suggests that there could be a hereditary 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. for this type of tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions..

Environmental factors and exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to certain chemicals or radiation may also increase the risk, although concrete evidence is still lacking. Research in this field is ongoing, and therefore much remains to be learned about the exact causes.

Symptoms

Very common symptoms:

Common symptoms:

The symptoms of a cardiac hemangiosarcoma are often non-specific and can appear suddenly. One of the most common symptoms is sudden weakness or collapse, caused by bleeding from the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. into the pericardiumThe pericardium is the sac around the heart, a double-walled membrane that surrounds the heart, protecting it from infection and facilitating its movement within the thorax / chest. Inflammatory conditions of the pericardium can lead to diseases such as pericarditis.. This condition can lead to a pericardialPericardial refers to anything related to the pericardium, the sac that surrounds and protects the heart. Pericardial diseases can affect heart function and often require specialized veterinary care. effusion, which impairs the heartbeat.

Other symptoms can include respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress, pale mucous membranes, an increased pulse, or rapid breathing. In some cases, sudden death can also occur without prior signs, making this disease particularly insidious.

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 a cardiac hemangiosarcoma often begins with a thorough physical examination and the dog’s 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.. The veterinarian may look for signs of heart problems, such as heart murmurs or an irregular heartbeat.

Imaging procedures such as X-rays and 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. examinations of the heart (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.) are crucial to confirm the presence of a tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions.. These procedures can help determine the size and location of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. and check whether a pericardialPericardial refers to anything related to the pericardium, the sac that surrounds and protects the heart. Pericardial diseases can affect heart function and often require specialized veterinary care. effusion is present.

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. can also be performed to assess the dog’s general health and identify signs of anemia or other changes in the blood count. In some cases, a fine-needle aspirationFine-needle aspiration is a minimally invasive diagnostic technique that uses a thin needle to extract cells or fluid from a tumor, lesion, or organ. This sample is then examined microscopically to make a diagnosis. of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. or a surgical biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions. may be required to make a definitive 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..

Therapy

Treatment of a cardiac hemangiosarcoma depends on the stage and spread of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions.. In many cases, the disease is already far advanced when it is diagnosed, which makes treatment difficult.

Surgical removal of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. may be an option if the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. is detected at an early stage and has not spread far. However, this operation can be risky as it involves the heart. ChemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. is frequently used to slow the growth of cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. cells and improve the dog’s quality of life. Various chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. drugs such as doxorubicin are often used to treat these tumors.

Additionally, palliativePalliative refers to treatments that aim to alleviate the symptoms of a disease without curing the disease itself. Palliative care focuses on improving the quality of life of patients with incurable diseases. 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 be used to alleviate symptoms and improve the dog’s quality of life. This includes pain management and the treatment of accompanying conditions such as pericardialPericardial refers to anything related to the pericardium, the sac that surrounds and protects the heart. Pericardial diseases can affect heart function and often require specialized veterinary care. effusion.

Prognosis and follow-up care

The prognosis for dogs with a cardiac hemangiosarcoma is generally poor. Due to the aggressive nature of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. and the frequently late 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., survival times are usually short. Without treatment, dogs survive on average only a few weeks to months after 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..

Even with aggressive treatment, including surgery and chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells., the average survival time is often only six to eight months. However, 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 vary depending on the individual case, and there are reports of dogs that have survived longer.

Prevention

There are no specific measures for the preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of hemangiosarcomas, as the exact causes are not yet fully understood. However, a healthy lifestyle and regular veterinary check-ups can help monitor the dog’s overall health and detect potential problems early.

For breeds that are genetically predisposed, it may be useful to consider genetic counseling to assess the risk. Research in this area could lead to better preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. strategies in the future, but currently such options are limited.

Regular veterinary examinations are crucial, especially for older dogs or those belonging to susceptible breeds. Early detection can help improve treatment options and extend the dog’s quality of life.

Outlook on current research

Cardiac hemangiosarcoma, also known as heart cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. in dogs, is an aggressive and unfortunately often fatal cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas.. Current research focuses on better understanding the genetic and molecular mechanisms that lead to the development and spread of these tumors. Scientists are particularly investigating the genetic changes and molecular signatures that occur in affected dogs to identify specific biomarkers that could be used for earlier 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..

Another important area of research concerns the development and testing of new treatment methods. While surgical removal of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. and chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. are currently the main treatment options, intensive work is being done on the development of targeted therapies. These therapies aim to exploit specific molecular vulnerabilities of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. to stop or slow cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. growth. Some studies are also investigating the possibility of using immunotherapies, where the dog’s immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. is stimulated to fight cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. cells more effectively.

In clinical practice, the role of personalized treatment approaches is also increasingly recognized. By analyzing the genetic profile of a tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions., individually adapted 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. strategies can be developed that are better tailored to the specific characteristics of each dog’s tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions.. InitialInitial means beginning or at the start. In medicine, it can refer to the first symptoms of a disease or the first phase of a treatment process. results suggest that these approaches have the potential to extend survival times and improve the quality of life of affected animals.

Additionally, there are promising approaches to improving diagnostics, including the development of non-invasive imaging procedures and blood tests that could enable earlier detection of hemangiosarcomas. Research in this field is particularly important because the disease is often only diagnosed at an advanced stage when treatment options are limited.

International research collaborations and the involvement of dog owners in clinical trials are crucial to achieving progress in the development of new diagnostic and treatment methods. Through the collaboration of veterinarians, researchers, and industry, innovative approaches can be transferred more quickly into clinical practice, which could ultimately lead to better treatment outcomes for affected dogs.

Frequently asked questions (FAQs)

What is a hemangiosarcoma?

A hemangiosarcoma is a malignant tumor that arises from the cells of the blood vessels. In dogs, it frequently occurs in the heart, spleen, or skin and is known for its aggressive growth and tendency to metastasize.

What symptoms does a dog with cardiac hemangiosarcoma show?

Symptoms can vary, but common signs include weakness, collapse, respiratory distress, pale mucous membranes, and reduced exercise tolerance. In some cases, sudden and severe symptoms can occur if the tumor bleeds.

How is a hemangiosarcoma diagnosed?

Diagnosis usually involves a combination of clinical examinations, blood tests, imaging procedures such as ultrasound or X-ray, and sometimes a biopsy of the tumor if this can be done safely.

What treatment options are there?

Treatment often includes surgical removal of the tumor, if possible, followed by chemotherapy. Treatment aims to slow tumor growth and maintain quality of life, although the prognosis is usually guarded.

What is the prognosis for dogs with cardiac hemangiosarcoma?

The prognosis is generally unfavorable, as these tumors are aggressive and are often only discovered at an advanced stage. The average survival time after diagnosis is often only a few months.

Can certain dog breeds be affected more often?

Yes, certain breeds such as German Shepherds, Golden Retrievers, and Labradors are more susceptible to developing hemangiosarcomas. The reasons for this are still the subject of research.

Are there preventive measures against hemangiosarcomas?

Currently, there are no specific measures for the prevention of hemangiosarcomas. However, a healthy lifestyle and regular veterinary examinations can help maintain the dog's overall health and detect other diseases early.

What role does genetics play?

Genetics plays a significant role in the predisposition to hemangiosarcomas. Researchers are trying to identify genetic markers that increase the risk in order to potentially develop earlier diagnosis and prevention strategies.

Are alternative therapies effective?

Some owners consider alternative or complementary therapies, such as herbal treatments or dietary adjustments. However, these should always be done in consultation with a veterinarian, as there is little scientific evidence for their effectiveness.

How can I help my dog with this diagnosis?

Supporting a dog with hemangiosarcoma includes providing a stress-free environment, following veterinary treatment plans, and working closely with veterinarians to ensure the best possible quality of life for the animal.