Osteosarcoma in dogs is a common condition of bone cancer, and it’s a condition that pet owners should be aware of. This aggressive cancer affects the long bones in the legs, but it can also occur in other bones in the body, especially for larger dog breeds.

This aggressive type of bone cancer originates in the osteoblasts, the cells primarily responsible for bone formation and remodeling. Osteosarcoma in dogs rapidly destroys healthy bone tissue while spreading to nearby areas, often creating significant pain and mobility issues. 

Canine cancer is a very serious condition. Here, you’ll get to know everything there is about osteosarcoma in dogs so you can give your dog the care it needs when the signs show up.

What are the Causes of Osteosarcoma in Dogs?

Typically, osteosarcoma is caused by the genetics, size, and age of a dog. While osteosarcoma can happen in any dog breed, some breeds are more likely to be at risk of the disease. Smaller dog breeds are less likely to be affected, while larger ones will be more commonly affected.

• Rottweilers

• Great Danes

• Irish Wolfhounds

• Saint Bernards

• Golden Retrievers

• Labrador Retrievers

• German Shepherds

When it comes to age, osteosarcoma typically affects dogs in their middle or senior years, with most cases diagnosed between 6 and 8 years of age. However, large and giant breeds often show signs earlier, sometimes as young as 2 or 3 years old. 

In addition to these factors, Dogs with a history of bone fractures or injuries may have a slightly higher risk of developing osteosarcoma at the site of the injury. Chronic inflammation, irritation, or improperly healed fractures can create situations where cancerous growth can happen.

While less established, some studies suggest that exposure to environmental carcinogens, such as radiation, chemicals, or certain toxins, could contribute to the development of osteosarcoma. For example, dogs that have undergone radiation therapy for other conditions might have an increased risk of bone cancer in the treated area.

What are the Symptoms of Osteosarcoma in Dogs?

The symptoms of osteosarcoma in dogs often lean toward mobility and physical issues that can worsen over time. Here are the common ones:

Lameness and Pain

One of the first and most common symptoms of osteosarcoma is lameness. Your dog may start intermittently limping, which can be mistaken for a minor injury or arthritis. Over time, the lameness becomes more severe.

This is caused by the tumor weakening the affected bone, making it painful for your dog to bear weight. Some of the key signs of this symptom include:

• Favoring one leg when walking.

• Reluctance to use affected leg.

• Limping that worsens over days or weeks.

• Sudden cries of pain when the limb is touched or used.

Swelling in the Affected Area

Osteosarcoma often causes visible swelling near the tumor site. This swelling is due to the aggressive nature of the tumor as it grows and invades nearby tissue. The affected area may also feel warm to the touch, and your dog may flinch or pull away when it’s handled. Common areas where swelling may occur include the front and back legs, as well as the jaws and hips.

Behavioral Changes

Dogs with osteosarcoma often show behavioral changes as a response to chronic pain. These changes can include:

• Lethargy or reluctance to play, walk, or climb stairs.

• Decreased appetite or interest in food.

• Restlessness or difficulty finding a comfortable position.

• Signs of depression, such as reduced interaction.

Pathological Fractures

As the tumor progresses, it can weaken the bone to the point of breaking with minimal stress. These are called pathological fractures and can occur suddenly, even during normal activities like walking or jumping. Such fractures are extremely painful.

General Symptoms

In addition to localized symptoms, osteosarcoma can cause systemic signs, especially if the cancer has spread to other organs. These may include:

• Weight loss.

• Difficulty breathing in some cases.

• Fatigue or decreased overall activity levels.

How is Osteosarcoma in Dogs Diagnosed?

Diagnosing osteosarcoma in dogs uses a combination of clinical examination, imaging techniques, and laboratory tests. Here’s how we do it:

Physical Examination

The diagnostic process for osteosarcoma in dogs begins with a physical examination. Our vets will check for swelling or any issues in the affected limb or area. Signs of pain and discomfort when the limbs are moved will also be observed.

Imaging Techniques

When diagnosing bone cancer in dogs, X-rays are the most common diagnostic imaging tool used. The affected bone typically shows characteristic signs, such as a "moth-eaten" appearance caused by bone destruction, a sunburst-like pattern indicating aggressive tumor growth, and possible fractures in the weakened bone. 

In some cases, a CT scan and MRI may be recommended and used to get a deeper view of your dog’s condition.

Laboratory Tests

To confirm the diagnosis of osteosarcoma, a biopsy is typically performed. We’ll do this by taking a small sample of tissue from your dog’s tumor for microscopic examination in our in-house laboratory. Additionally, blood tests will be done to assess your dog’s overall health.

How is Osteosarcoma in Dogs Treated?

Treating osteosarcoma in dogs requires a detailed approach specific to your dog’s condition. While the primary goal is to manage pain and improve quality of life, treatment can also help extend survival times in many cases. 

Surgical Intervention

Surgery is often the first step in treating osteosarcoma. These will be handled by our pet orthopedics. The two main surgical options are amputation and limb-sparing surgery.

• Amputation

This is the most common treatment for osteosarcoma in dogs. Removing the affected limb eliminates the primary source of pain and can prevent the tumor from causing further damage to the bone. Most dogs adapt surprisingly well to life on three legs, even large dog breeds. It just takes time.

• Limb-Sparing Surgery

In cases where amputation isn’t an option, limb-sparing surgery may be an alternative. This procedure involves removing the tumor and replacing the affected bone with a bone graft or implant. However, this option is seemingly more complex.

Chemotherapy

Because osteosarcoma often metastasizes, chemotherapy is typically recommended following surgery to target cancer cells that may have spread. Chemotherapy is generally well-tolerated in dogs, with fewer and milder side effects than in humans.

Radiation Therapy

For dogs that aren’t candidates for surgery, radiation therapy can be used to help manage your dog’s pain and slow the progression of the disease. This is a palliative treatment option designed to improve comfort and mobility rather than cure the cancer. Radiation can also be used in combination with surgery or chemotherapy.

Pain Management

Managing pain is a common part of osteosarcoma treatment in dogs, regardless of the chosen approach. Non-steroidal anti-inflammatory drugs are often the most common choice for pain management. Opioids and gabapentin are also choices we consider.

Conclusion

Osteosarcoma is a serious and aggressive form of bone cancer that requires prompt attention and informed decision-making. While it is most common in large and giant breed dogs, any dog can be affected. While the journey may be challenging, many dogs can experience a good quality of life with the right care and support.