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Osteosarcoma in Dogs: Understanding the Diagnosis

When a dog begins limping, slowing down on walks, or avoiding putting weight on one of its legs, it is quite common for us to think about common causes such as arthritis or even a minor injury or arthritis. However, if lameness is persistent or unexplained, especially when pain or swelling is also present, the pet deserves veterinary attention.

Unfortunately, one of the possible causes can be osteosarcoma. It is an aggressive form of bone cancer and the most common malignant bone tumor diagnosed in dogs. It can cause pain at the affected site and tends to spread, or metastasize, to other areas of the body.

Thus, recognizing changes in your pet’s normal movement and comfort does not mean assuming the worst, as many orthopedic conditions can cause similar symptoms. Instead, it is important to know what is normal or not to help you recognize when a change persists long enough that further investigation is needed.

What Is Osteosarcoma in Dogs?

Canine osteosarcoma is a malignant tumor arising from the cells that form the bones. This cancer produces abnormal bone tissue and at the same time progressively damages the normal bone, which can make the affected area painful and structurally weaker.

It can develop in different bones, but in dogs it frequently affects the limbs, particularly the long bones, which is called appendicular osteosarcoma. Osteosarcoma can also occur in other locations, including the skull, jaw, ribs, pelvis, vertebrae, etc.
Osteosarcoma is considered aggressive for two important reasons. First, the primary tumor can cause substantial local bone destruction, pain, and sometimes a pathologic fracture, meaning the weakened bone breaks with relatively little trauma. Second, osteosarcoma has a high metastatic potential.

The lungs are one of the most common sites of metastasis. Importantly, a dog may already have microscopic metastatic disease even when chest imaging does not reveal visible tumors. This is one reason treatment often involves both local control of the primary tumor and systemic treatment aimed at metastatic disease.

Osteosarcoma accounts for the majority of primary malignant bone tumors diagnosed in dogs.

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Causes of Osteosarcoma in Dogs

There is no single known cause of osteosarcoma in dogs; a combination of genetic, biological, and physical factors may play a role.

Research has shown that large and giant-breed dogs such as Rottweilers, Great Danes, Irish Wolfhounds, Greyhounds, Golden Retrievers, and German Shepherds have a substantially greater risk of developing osteosarcoma than smaller dogs. Research has also identified breed-related differences, suggesting that genetics contribute to susceptibility.

Age also may play a role, as osteosarcoma is more commonly diagnosed in middle-aged and older dogs, although young dogs can also develop the disease.

Other potential conditions have been investigated, such as body condition (obesity), previous orthopedic disease, sex, and neuter status.

What Are the First Signs of Osteosarcoma in Dogs?

You may notice:

Limping that can be persistent or progressive
Reluctance to put weight on one limb
Pain in the affected area
Noticeable or firm swelling over a bone
Loss of interest in walking, running, jumping, playing
Difficulty climbing stairs or getting up
Changes in the gait or posture
In more severe cases, the dog can have intense pain that is associated with a fracture

How Is Osteosarcoma in Dogs Diagnosed?

The diagnosis generally includes a detailed medical history and physical examination by your veterinarian that will check the overall health, painful area, and might assess gait, the joint movements, swelling, muscle mass, etc.

X-rays may show characteristic changes in the affected bone that are related to osteosarcoma. Additional imaging may be recommended, such as a CT scan.

Your vet may also recommend collecting cells or tissue from the affected area for a bone biopsy that will allow the tissue to be examined by a veterinary pathologist and can provide a definitive diagnosis.

Additional testing may also be performed to determine if there is evidence of cancer spread or metastases. This process is called staging and can include imaging of the chest, bloodwork, and other diagnostic tests as needed.

Treatment Options for Osteosarcoma in Dogs

Treatment of osteosarcoma in dogs will depend on the affected location, stage of disease, overall health, mobility, and individual needs. For the affected limb, amputation is usually done to remove the primary tumor and also to control pain. Many dogs can adapt well to three-legged mobility. Unfortunately, osteosarcoma has a high risk of metastasis. Thus, chemotherapy is usually performed after surgery to try to address microscopic metastatic disease. Other options may include radiation therapy and palliative approaches when surgery is not recommended. A veterinary oncologist is the best person to help determine which options are the most appropriate based on each individual dog’s needs.

Osteosarcoma in Dogs: Prognosis & Quality of Life

The prognosis varies between dogs and depends on many factors such as the tumor location, whether there is metastasis, treatment, and the dog’s overall health.

Quality of life is also very important because this type of cancer can be painful. Therefore, pain management, keeping the dog comfortable, appetite, activity levels, and interaction with family should be regularly assessed.

Supportive Care for Dogs With Osteosarcoma

Alongside veterinary cancer treatment, supportive care may help maintain comfort and overall wellness; this can include appropriate nutrition and hydration, healthy body condition, comfortable bedding and non-slip flooring, ramps or mobility assistance, pain management, monitoring appetite, etc.

For families interested in an integrative approach, the NHV Osteosarcoma Super Kit may be incorporated as complementary support alongside veterinary care.

The kit includes NHV Natures Immuno, which contains medicinal mushroom extracts that help support and modulate normal immune function. It is an important part of supporting the body during serious illness such as osteosarcoma.

NHV ES-Clear provides herbal support for immune health and the body’s natural elimination processes, which can be particularly valuable when supporting overall wellness during cancer care.

NHV Yucca helps support a normal inflammatory response, appetite, digestion, and comfort, which may be especially helpful for pets experiencing discomfort or reduced appetite.

Together, these formulas provide broader supportive care for immune function, comfort, appetite, and overall quality of life while a dog undergoes veterinarian-directed treatment for osteosarcoma. The supplements are intended to support overall wellness based on the supportive properties of their herbal ingredients. However, they should not be considered a replacement for veterinary cancer treatment.

Concluding Thoughts

Osteosarcoma can be an aggressive cancer, and when it is diagnosed, treatment and supportive care should be individualized to take into consideration both cancer management and quality of life.

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