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Lymphoma, Lymphosarcoma (Tumors of the Lymphatic System) in Dogs

Occurrence: common
Location of illness: General/Whole body

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

A lymphoma, also known as lymphosarcoma, 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. 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. of the lymphatic system in dogs. It mainly affects the lymph nodes but can also affect other organs such as the spleen, liver, and bone marrow.

The most important facts at a glance

Lymphomas are Tumors of the lymphatic system in dogs that are caused by uncontrolled proliferation of lymphocytesLymphocytes are a group of white blood cells crucial for the body's adaptive immune response. There are different types, including B cells, T cells, and natural killer cells, each with specific functions in the immune system.. These 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. cells can accumulate in the lymph nodes and form Tumors or spread throughout the body. The exact causes are often unknown, but genetic factors, environmental factors, and viralViral refers to viruses and their effects on the organism. Viral infections in dogs and cats can range from harmless colds to severe, life-threatening diseases. infections can play a role. Certain dog breeds, such as Golden Retrievers and Boxers, are particularly susceptible to lymphomas. Symptoms can include enlarged, firm lymph nodes, loss of appetite, and weakness. Physical examinations, biopsies, and imaging procedures are used for 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.. The most common treatment is 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., which slows 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. 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. depends on the type of lymphoma and the 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. response; many dogs can achieve an extended quality of life through treatment. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is difficult, but a healthy lifestyle and protectionProtection refers to safeguarding against diseases or harm. In veterinary medicine, this can include protecting animals through vaccinations, the use of parasite control products, or providing a safe environment. from environmental toxins can reduce the risk. Research is focusing on genetic predispositions, improved diagnostic methods, and new therapeutic approaches to improve the survival rates and quality of life of affected dogs.

Causes

The lymphatic system is an integral part of the 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., consisting of a network of lymphatic vessels, lymph nodes, and lymphatic organs such as the spleen and tonsils. It plays a crucial role in fighting infections and removing waste products from the body. LymphocytesLymphocytes are a group of white blood cells crucial for the body's adaptive immune response. There are different types, including B cells, T cells, and natural killer cells, each with specific functions in the immune system., a type of white blood cell, are the main players in this system.

Lymphomas arise when there is an uncontrolled proliferation of lymphocytesLymphocytes are a group of white blood cells crucial for the body's adaptive immune response. There are different types, including B cells, T cells, and natural killer cells, each with specific functions in the immune system.. These 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. cells can accumulate in the lymph nodes and form Tumors or migrate to other parts of the body. The exact cause of this uncontrolled cell division is often unknown, but genetic factors, environmental factors, and viralViral refers to viruses and their effects on the organism. Viral infections in dogs and cats can range from harmless colds to severe, life-threatening diseases. infections are considered possible triggers.

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. plays a significant role in certain dog breeds, as some breeds such as Golden Retrievers, Boxers, and German Shepherds have a higher susceptibility to lymphomas. Environmental factors such as 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 pesticidesPesticides are chemical or biological substances used to control pests, including insects, weeds, and fungi. In dogs and cats, exposure to certain pesticides can be harmful to health and lead to signs of poisoning. can also increase the risk. In addition, there is evidence that infections with certain viruses can increase the risk of developing lymphomas.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

Weight Loss

The symptoms of lymphoma can vary depending on the organ affected and 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. A common sign is painless Swelling of the lymph nodes, often in the neck, groin, or behind the knees. These Swellings are often the first sign that alerts the owner.

Other symptoms may include general weakness, loss of appetite, weight loss, and increased Lethargy. If internal organs such as the spleen or liver are affected, dogs may show signs of AbdominalThe term “abdominal” refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. pain, Vomiting, or DiarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems.. If the bone marrow is involved, anemia or other blood count changes may occur, which can lead to pale mucous membranes, increased susceptibility to infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., or Bleeding.

In advanced stages of the disease, 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 if the lymph nodes in the chest area are enlarged and pressing on the tracheaThe trachea, or windpipe, is a tubular organ that carries air from the upper respiratory tract to the bronchi in the lungs. It consists of ring-shaped pieces of cartilage that ensure it remains open. or lungs.

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 lymphoma usually begins with a thorough physical examination, during which the veterinarian examines the lymph nodes for Swelling. However, 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. usually requires further investigation.

A fine needle aspiration or 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. of the enlarged lymph nodes is often performed to obtain cells for microscopic examination. These samples allow a pathologist to confirm the presence of malignant lymphocytesLymphocytes are a group of white blood cells crucial for the body's adaptive immune response. There are different types, including B cells, T cells, and natural killer cells, each with specific functions in the immune system..

Additional tests may include blood tests to assess the dog’s general health and detect possible changes in blood formation. Imaging procedures such as X-rays or 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. can be used to assess the spread of the disease to other organs. In some cases, a bone marrow biopsy may also be required to check for bone marrow involvement.

Therapy

The treatment of lymphomas in dogs can vary, depending on the type and stage of the disease, as well as the general health of the dog. The most common form 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. is 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., which aims to destroy the cancerous cells or slow their growth.

There are 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. protocols that can be used, with the CHOP protocol (cyclophosphamide, doxorubicin, vincristine, and prednisone) being one of the most frequently used. This treatment can be given over several months and requires regular check-ups. Side effects such as Vomiting, DiarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems., or a temporary weakening of the 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. may occur but are usually well controlled.

In some cases, radiation therapyRadiation therapy is the use of radiation, most often to treat cancer. It can be used to kill cancer cells or slow their growth without significantly damaging surrounding healthy tissue. may be considered, especially if only a limited area is affected. Surgical removal of Tumors is less common, as lymphomas are often systemic and not limited to one area.

Prognosis and follow-up care

The prognosis for dogs with lymphoma depends on various factors, including the type of lymphoma, the stage of the disease at 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 the dog’s response to 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.. In general, many dogs with lymphoma who are treated appropriately can experience a significant extension and improvement in their quality of life.

With 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., remission can be achieved in many cases, which means that the disease is temporarily under control and no clinical signs are present. The duration of remission can vary greatly, with some dogs remaining in remission for several months to several years.

Unfortunately, lymphoma is still considered incurable in most cases, and the disease may eventually return. Life extension and quality of life depend heavily on aggressive treatment and the individual response of the dog.

Prevention

Since the exact causes of lymphomas are often not clear, there are no specific preventive measures that can guarantee that a dog will not develop lymphoma. However, some general measures can be taken to minimize the risk.

A healthy lifestyle, including a balanced diet and regular exercise, can strengthen the 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. and contribute to general health. Minimizing 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 environmental toxins, such as pesticidesPesticides are chemical or biological substances used to control pests, including insects, weeds, and fungi. In dogs and cats, exposure to certain pesticides can be harmful to health and lead to signs of poisoning. and tobacco smoke, can also be helpful.

Regular veterinary check-ups are crucial to detect early signs of the disease and enable timely treatment. For owners of breeds that are genetically more susceptible to lymphomas, it is particularly important to be vigilant for possible symptoms and seek veterinary advice immediately if changes are noticed.

Outlook on current research

Research into lymphomas and lymphosarcomas in dogs is constantly evolving, as these cancers are one of the most common 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. diseases in dogs. Scientists are focusing on better understanding the causes and mechanisms of the disease in order to develop more effective treatments and possibly preventive measures. A significant area of research is 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.. Researchers are investigating which genetic factors make certain dog breeds more susceptible to lymphomas in order to develop targeted breeding strategies that could reduce the risk.

Another focus is on improving diagnostics. The development of advanced imaging techniques and molecular tests could enable veterinarians to detect lymphomas earlier and more accurately. This is crucial, as 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. is often associated with a better prognosis. Some studies are investigating the use of liquid biopsies, in which circulating 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. cells in the blood are searched for to enable non-invasive 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..

There are also exciting advances in 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.. Research is focusing on personalized medicine approaches, in which treatment is tailored to the specific genetic makeup of a 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.. The goal is to develop therapies that specifically attack 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 while sparing healthy cells. This could lead to better tolerability and effectiveness of the treatment. Immunotherapies, which stimulate 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. 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, are also being intensively researched.

Another area in which promising results are being achieved is the development of new chemotherapeutic agents and the optimization of existing protocols. Researchers are testing combinations of drugs to prevent the development of resistanceResistance refers to the ability of microorganisms to withstand the effects of antibiotics, antifungals, or other antimicrobial drugs. Resistance can also refer to the body's ability to be insensitive to diseases or toxins. and increase effectiveness. Alternative therapies, such as herbal remedies and nutritional approaches, are also being investigated to provide supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. treatment options.

In addition, the quality of life of dogs during treatment is increasingly being focused on. Studies are analyzing how side effects 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. can be reduced and what measures can help to improve the well-being of the animals. The role of 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. care is also being increasingly investigated to ensure that dogs in the advanced stages of the disease can live as pain-free and comfortable as possible.

Overall, current research shows promising approaches to improving 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., treatment and ultimately 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. of dogs with lymphomas. Interdisciplinary collaboration between geneticists, oncologists, veterinarians and other specialists is crucial to further advance progress in this area. It is generally expected that these efforts will significantly improve the survival rates and quality of life of dogs with lymphomas in the near future.

Frequently asked questions (FAQs)

What is lymphoma in dogs? A lymphoma is a 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 affects a dog’s lymphatic system, which includes lymph nodes, spleen, liver, and other organs. It is one of the most common cancers in dogs and can occur in various forms.
What symptoms do dogs with lymphomas show? The most common symptoms include swollen lymph nodes, weight loss, loss of appetite, Lethargy, and Vomiting. Symptoms may vary depending on the organ affected.
How is lymphoma diagnosed in dogs? 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 physical examination, blood tests, imaging procedures, and a 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. of the affected lymph nodes or organs.
Can lymphomas be cured in dogs? A complete cure is rare, but many dogs can be put into remission with 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. and other treatments, meaning the disease is under control and the dog has a good quality of life.
What treatment options are available for lymphomas in dogs? The most common treatment is 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., which is often combined with other medications. In some cases, radiation therapyRadiation therapy is the use of radiation, most often to treat cancer. It can be used to kill cancer cells or slow their growth without significantly damaging surrounding healthy tissue. or surgery may also be considered.
How long can dogs with lymphoma live? Life expectancy depends on many factors, including the form of lymphoma, the stage of the disease, and the response to treatment. With appropriate 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., dogs can often live for months to years.
Are there risk factors for lymphomas in dogs? Certain breeds such as Boxers, Bullmastiffs, and Golden Retrievers are at higher risk. Environmental factors and genetic predispositions can also play a role.
Can diet affect the risk of lymphomas in dogs? While a balanced diet is important for general health, there are no specific dietary measures that significantly reduce the risk of lymphomas. However, good nutrition can improve the quality of life of affected dogs.
Are lymphomas painful in dogs? Lymphomas themselves are often not painful, but they can cause symptoms that cause discomfort or Pain, especially if organs are affected. Appropriate treatment can help relieve these symptoms.
Can a dog with lymphoma live a normal life? With the right treatment, many dogs can live a relatively normal life, especially if the disease is in remission. However, regular veterinary check-ups and adapted care are important to maintain quality of life.