Home » Diseases » In dogs » Synovial sarcoma (joint cancer)

Synovial sarcoma (joint cancer) in Dogs

Occurrence: very rare
Location of disease: Legs

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

SynovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. is a rare and aggressive form of joint 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 the connective tissue in the joints of dogs. These tumors typically develop near joints and can lead to significant pain and mobility restrictions.

The most important facts at a glance

Synovial sarcomas are aggressive soft tissue sarcomas in dogs that originate in the tissues lining the joint capsules. The exact cause is unknown, but genetic factors and chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. joint inflammation could play a role. Affected dogs often show symptoms such as lameness, swelling in the joints, and pain. 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. requires a thorough examination, often with X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions. and imaging procedures like CT or MRI, as well as 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. to confirm the 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. 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.. Treatment is multidisciplinary and usually includes 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., 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., and possibly 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.. Pain management is crucial to improve the dogs’ quality of life.

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 synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. varies but is often guarded to poor, as these tumors can grow and spread aggressively. Early detection and complete removal offer the best chance for a longer survival time. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is difficult since the causes are not fully understood, but regular veterinary check-ups, a balanced diet, and avoiding joint injuries can be helpful. Research in this field investigates genetic and molecular foundations and develops new therapies, including immunotherapy and improved surgical techniques. Advances in imaging and new drugs to inhibit 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. growth are also promising areas of research.

Causes

Synovial sarcomas are soft tissue sarcomas that originate in the synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. tissue lining the joint capsules. These tumors are known for their invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. growth into surrounding soft tissues and bones, making them particularly destructiveDestruction means "demolition." In medicine, it refers to the destruction of cells, tissues, organs, or body parts. The growth of malignant Tumors is also usually accompanied by destruction of the surrounding tissue..

The exact causes of synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in dogs are largely unknown. However, it is suspected that genetic factors could play a role. Certain breeds such as Dobermans and German Shepherds seem to be affected more frequently, suggesting a possible 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..

Another factor being considered is chronic inflammatory conditions or traumas in the joints, which can increase the risk of developing 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. tumors. This constant irritation could promote cell growth and division, leading to 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. changes.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

Fever

Symptoms of synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in dogs can start subtly and increase in intensity over time. The most common sign is lameness, which may be episodic at first but gradually develops into constant lameness. This lameness is often associated with pain, especially during movement or pressure on the affected joint.

Additionally, swelling around the affected joint may be observed. This swelling can be firm or soft and may increase in size over time. Dogs with synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. may also show general signs of malaise, such as decreased appetite, weight loss, and a reduced activity level.

In advanced stages, movement of the affected joint can be severely restricted, and the dog may show signs of muscle atrophyMuscle atrophy is the loss of muscle mass that can be caused by inactivity, malnutrition, or certain diseases. In dogs and cats, muscle atrophy can occur due to chronic diseases, aging, or after prolonged immobilization. as the muscles around the affected joint begin to waste away due to lack of use.

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 synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. typically begins with a thorough clinical examination and a detailed 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. taken by the veterinarian. X-rays are often used as the first diagnostic step to detect changes in the bone around the affected joint, although soft tissue sarcomas are not always visible on X-rays.

Advanced imaging procedures such as 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., computed tomography (CT)Computed tomography (CT) is an imaging technique that uses X-rays and computer technology to create cross-sectional images of the body. It enables a detailed view of bones, organs, and other structures and is used for the diagnosis of injuries, diseases, and for planning medical interventions., or 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. may be required to assess the 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. and its relationship to surrounding structures in more detail. These procedures can help determine the size and exact 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..

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 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. or a biopsy 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 perform a histopathologicalHistopathological refers to the microscopic examination of tissue samples for the diagnosis of diseases. This technique is used to identify the specific characteristics of diseases at the cellular level in dogs and cats. examination. This examination allows for confirmation of the 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. 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 determination of the specific type of sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment..

Therapy

Treating synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas usually requires a multidisciplinary approach. 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. is often the preferred treatment option, especially 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. For tumors that have invaded the bone, amputationAn amputation is the surgical removal of a body part, usually a limb or part of a limb. In veterinary medicine, amputation is performed to relieve Pain or prevent the spread of diseases, such as cancer. of the affected limb may be necessary to ensure complete removal.

In addition to surgical removal, 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. can be used to kill remaining cancer cells and reduce the risk of relapse. In some cases, 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 also considered, especially 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. cannot be completely removed or if metastasis is suspected.

Pain management is an essential part 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. to improve the affected dog’s quality of life. Painkillers and anti-inflammatory medications can help relieve pain and improve mobility.

Prognosis and follow-up care

The prognosis for dogs with synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. depends on several factors, including 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., the presence of metastasesA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body., and the response to treatment. In general, 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 guarded to poor, as synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas tend to grow aggressively and spread to other parts of the body.

Dogs where 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 early and completely removed have the best 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.. The average survival time 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. can range from several months to a year or longer, depending on the effectiveness of the treatment and the dog’s overall health.

Prevention

Since the exact causes of synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas are not fully understood, there are no specific preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. measures that can reliably prevent the development of these tumors. Nevertheless, some general strategies can help reduce the risk.

Regular veterinary check-ups are crucial for detecting early signs of health problems. Dog owners should watch for changes in their pets’ gait or mobility and consult a veterinarian quickly if abnormalities occur.

A balanced diet and regular exercise can help strengthen a dog’s overall health and 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., which could potentially reduce the risk of developing 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. tumors. In addition, injuries and chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. joint inflammation should be avoided or treated quickly to prevent long-term damage.

Outlook on current research

Research into synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in dogs is a constantly evolving field focusing on understanding biological mechanisms and developing new treatment strategies. SynovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas are a rare form of cancer originating from the soft tissues in and around the joints. This 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. can be aggressive and requires early detection and treatment to improve the well-being of the affected animal.

Current research projects are investigating the genetic and molecular basis of synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in dogs. Scientists use advanced techniques such as genomic analysis to identify specific genetic mutations associated with the development and 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 these tumors. These findings could help develop targeted therapies that specifically address the molecular characteristics 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..

Another area of research is the development of immunotherapeutic approaches. These methods aim to strengthen 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 more effectively. Studies on immunotherapy in dogs are promising and could play an important role in treating synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in the future.

In addition to immunotherapy, research is also being conducted to improve surgical techniques. Since 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. is often the primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. treatment option, researchers are working to develop minimally invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. techniques that shorten recovery time and improve the dogs’ quality of life. Advances in imaging technology allow for more precise surgeries and better assessment 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. size and spread.

Another exciting area is the research into drugs specifically targeting synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas. Clinical trials with new drugs aimed at inhibiting 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. growth and preventing metastasisA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body. are underway. These studies could open up new treatment options and improve survival rates for dogs with synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas.

In summary, research into synovialSynovial refers to the synovial fluid or the tissue that lines joint capsules. Synovial fluid acts as a lubricant for joints and reduces friction during movement. sarcomas in dogs is a dynamic and promising field. Through continuous studies and innovations, scientists hope to significantly improve 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 management of this disease.

Frequently asked questions (FAQs)

What is a synovial sarcoma in dogs?

A synovial sarcoma is a rare type of cancer that originates from the soft tissues in and around a dog's joints. It is an aggressive tumor that can grow quickly and spread to other parts of the body. -

What symptoms occur in a dog with synovial sarcoma?

Symptoms can include lameness, swelling, and pain in the affected joint. In some cases, there may also be a visible lump or enlargement of the joint. General signs such as weight loss and decreased appetite can also occur. -

How is a synovial sarcoma diagnosed in dogs?

Diagnosis is usually made through a combination of clinical examination, imaging procedures such as X-ray or MRI, and a biopsy of the affected tissue. The biopsy allows for the examination of cells under a microscope to identify the tumor. -

What treatment options are available for dogs with synovial sarcoma?

Treatment can include surgical removal of the tumor, chemotherapy, and/or radiation therapy. The choice of treatment depends on the size and stage of the tumor as well as the dog's overall health. -

What is the prognosis for a dog with synovial sarcoma?

The prognosis depends on various factors, including the tumor stage and treatment options. Early detection and aggressive treatment can improve survival chances, but in many cases, the prognosis is guarded to serious. -

Can synovial sarcomas be prevented in dogs?

There are no specific prevention measures for synovial sarcomas. However, a healthy lifestyle and regular veterinary check-ups can help maintain your dog's overall health and detect potential health problems early. -

Which breeds are more susceptible to synovial sarcomas?

Synovial sarcomas can occur in dogs of any breed, but larger breeds seem to have a higher risk. Examples include German Shepherds, Labrador Retrievers, and Rottweilers. -

Are synovial sarcomas painful for dogs?

Yes, synovial sarcomas can be very painful for dogs, especially if the tumor affects the joint. Pain management is an essential part of treatment to ensure the well-being of the affected dog. -

Are there alternative therapies for synovial sarcomas in dogs?

Some pet owners explore alternative therapies such as acupuncture, homeopathy, or herbal remedies to improve their dog's quality of life. However, these should always be done in consultation with an experienced veterinarian, as they cannot replace conventional treatments. -

How can I help my dog with synovial sarcoma?

In addition to veterinary treatment, you can help your dog by providing a comfortable environment, managing their pain, and ensuring a balanced diet. Regular veterinary check-ups are important to monitor your dog's progress and overall well-being.