Canine Osteosarcoma

At Animal Cancer Care Clinic (ACCC), we understand that receiving a diagnosis of osteosarcoma, an aggressive bone cancer, in your beloved dog can be devastating news. Please know that our dedicated and compassionate team is here to support you and your furry companion every step of the way. While osteosarcoma is a serious condition, we have advanced diagnostic and treatment options aimed at managing pain, slowing the progression of the disease, and maximizing your dog’s quality of life.

What is Osteosarcoma?

Osteosarcoma is a malignant tumor that originates in the bone cells (osteoblasts). It is the most common primary bone cancer in dogs, accounting for the vast majority of bone tumors we see. While it can occur in any bone, it most commonly affects the long bones of the limbs, particularly the front legs (distal radius, proximal humerus) and hind legs (distal femur, proximal tibia). Less frequently, it can occur in other bones such as the ribs, spine, or skull.

Osteosarcoma is characterized by its rapid and aggressive growth and its tendency to spread (metastasize) to other parts of the body, most commonly the lungs.

What Causes Osteosarcoma in Dogs?

The exact cause of osteosarcoma in dogs is not fully understood in most cases. However, several factors are believed to increase the risk:

Large and Giant Breeds: Osteosarcoma is significantly more common in large and giant breed dogs, such as Great Danes, Irish Wolfhounds, Saint Bernards, Rottweilers, and Doberman Pinschers. Rapid bone growth in these breeds may play a role.
Age: While it can occur in dogs of any age, there are typically two peak incidences: one in young, rapidly growing large and giant breeds (around 1-2 years old) and another in older large and giant breeds (around 7-9 years old).
Genetics: A genetic predisposition is suspected in certain breeds.
Previous Bone Injury or Chronic Inflammation: While not a direct cause, some studies suggest a possible link between previous bone fractures, chronic inflammation, or the presence of metal implants and the development of osteosarcoma at those sites.

It’s important to reassure you that osteosarcoma is not contagious to other pets or humans.

Signs and Symptoms of Osteosarcoma:

The signs of osteosarcoma in dogs often develop gradually and can initially be subtle:

Lameness: This is the most common presenting sign. The lameness, usually limping, may be intermittent at first, worsening over time and eventually becoming constant and severe.
Pain: Dogs with osteosarcoma typically experience significant pain in the affected limb. They may whine, limp, be reluctant to put weight on the leg, or show signs of discomfort upon palpation of the bone.
Swelling: A firm swelling or thickening may be noticeable around the affected bone. This swelling can increase in size as the tumor grows.
Lethargy and Decreased Appetite: As the discomfort intensifies or if the cancer has spread, your dog may become lethargic and lose interest in eating.
Fracture (Pathologic Fracture): In some cases, the bone weakened by the tumor can fracture spontaneously or with minimal trauma. This is called a pathologic fracture and is often very painful.

If your dog exhibits any of these signs, especially persistent lameness or swelling in a limb, it’s important to seek veterinary attention promptly.

How is Osteosarcoma Diagnosed?

Diagnosing osteosarcoma typically involves a combination of the following:

Physical Examination: A veterinarian will perform a thorough physical examination, paying close attention to any lameness, pain, or swelling in the limbs.
Radiographs (X-rays): Radiographs of the affected limb are essential and often highly suggestive of osteosarcoma. They can reveal characteristic bone changes such as bone lysis (destruction), bone production, and elevation of the periosteum (the outer layer of bone).
Bone Sample: A bone biopsy is necessary for a definitive diagnosis of osteosarcoma and to rule out other bone conditions such as fungal infections or other types of bone tumors. Biopsies can be obtained using a fine needle aspirate, specialized bone biopsy needle, or through a surgical procedure. Our team will carefully consider the best approach for your dog.
Chest Radiographs (X-rays) or CT Scan of the Chest: Because osteosarcoma has a high rate of metastasis to the lungs, imaging of the chest is crucial to check for any evidence of spread at the time of diagnosis. A CT scan of the chest is more sensitive than radiographs for detecting small lung nodules.
Blood Work: A complete blood count (CBC) and serum chemistry panel are typically performed to assess your dog’s overall health. While blood work is usually normal in dogs with localized osteosarcoma, it can provide important information about their general condition.

Treatment Options for Canine Osteosarcoma:

At Animal Cancer Care Clinic (ACCC), our treatment approach for osteosarcoma focuses on pain management, controlling local disease, and addressing metastasis to improve your dog’s quality of life and survival time. The standard of care typically involves a combination of therapies:

Pain Management: Osteosarcoma is a painful condition, and effective pain management is paramount. This often involves a combination of medications, including non-steroidal anti-inflammatory drugs (NSAIDs), opioids, and other pain relievers. Our team at ACCC will develop a comprehensive pain management plan for your dog.
Amputation: Surgical removal of the affected limb (amputation) is often recommended as the most effective way to eliminate the primary source of pain and the local tumor. Dogs generally adapt very well to life on three legs, and amputation can significantly improve their comfort and quality of life.
Limb-Sparing Surgery (Less Common): In select cases, where the tumor is in a favorable location and there is no significant soft tissue involvement, a limb-sparing surgery may be an option. This involves surgically removing the tumor and replacing the affected bone segment with a bone graft or metal implant. However, limb-sparing surgery is often associated with a higher risk of local recurrence and infection compared to amputation and may not be suitable for all dogs. This procedure is not performed at ACCC at this time.
Chemotherapy: Because osteosarcoma has a high rate of metastasis (especially to the lungs), chemotherapy is a critical component of the treatment plan, even if the primary tumor is removed by amputation or limb-sparing surgery. Chemotherapy helps to target and kill microscopic cancer cells that may have already spread. Our veterinary oncologists at ACCC will develop a personalized chemotherapy protocol for your dog.
Radiation Therapy (Palliative): Radiation therapy is not typically used as the primary treatment for osteosarcoma in the limbs. However, palliative radiation therapy can be very effective in reducing pain associated with the primary tumor, especially in dogs who are not candidates for surgery or as a supportive measure.
Bisphosphonates: These are medications that can help to reduce bone pain and slow down bone destruction associated with osteosarcoma. They can improve comfort and may have some anti-tumor effects.

What to Expect During and After Treatment:

If your dog undergoes treatment for osteosarcoma at Animal Cancer Care Clinic (ACCC), you can expect:

Comprehensive Pain Management: Our team will work diligently to ensure your dog’s pain is well-controlled throughout the treatment process.
Close Monitoring: We will closely monitor your dog’s response to treatment and manage any potential side effects.
Rehabilitation (After Amputation or Limb-Sparing Surgery): For dogs undergoing surgery, we will provide guidance on post-operative care and may recommend physical rehabilitation to help them adapt and regain mobility.
Regular Follow-Up Appointments: These appointments will involve physical examinations, monitoring for signs of metastasis (e.g., coughing, difficulty breathing), and potentially repeat chest radiographs or CT scans.

Prognosis for Canine Osteosarcoma:

The prognosis for dogs with osteosarcoma depends on several factors, including:

Location of the Tumor: Osteosarcoma in appendicular (limb) bones generally has a better prognosis than osteosarcoma in axial (spine, ribs, skull) bones, although there are exceptions.
Presence of Metastasis: The presence of detectable metastasis at the time of diagnosis significantly worsens the prognosis.
Response to Treatment: Dogs that respond well to surgery and chemotherapy tend to have longer survival times.
Overall Health of the Dog: Dogs with significant underlying health issues may have a less favorable prognosis.

With amputation alone, the median survival time for dogs with appendicular osteosarcoma is typically around 4-6 months due to the high rate of metastasis. However, with amputation followed by chemotherapy, the median survival time can often be extended to 10-14 months or even longer in some cases. We can see similar outcomes with a combination of stereotactic radiation therapy, bisphosphonates, and chemotherapy. Palliative radiation therapy can provide pain relief but does not typically significantly extend survival time.

We will discuss the potential prognosis for your dog based on their individual circumstances and the chosen treatment plan at ACCC. Our goal is to provide realistic expectations while focusing on maximizing their comfort and quality of life for the time they have.

Coping with an Osteosarcoma Diagnosis:

Receiving a diagnosis of osteosarcoma for your dog is incredibly difficult. Please know that the team at ACCC is here to offer not only the best possible medical care for your dog but also compassionate support for you and your family during this challenging time.

We encourage you to ask us any questions you have and to share your feelings and concerns openly. We want you to feel informed and supported as you make important decisions about your dog’s care.

Our commitment is to work with you to develop a treatment plan that aligns with your goals and your dog’s best interests, prioritizing their comfort and quality of life every step of the way.

Questions to Ask Your Veterinarian at ACCC:

To help you better understand your dog’s condition and the treatment options available at Animal Cancer Care Clinic, here are some questions you may find helpful to ask us:

Where is the osteosarcoma located in my dog?
Has the cancer spread to other parts of the body (metastasis)? If so, where?
What are the treatment options available for my dog’s osteosarcoma?
What are the goals of each treatment option (e.g., pain relief, slowing progression, extending survival)?
What are the potential side effects of the recommended treatment plan? How will these be managed?
What is the expected prognosis for my dog with the recommended treatment?
How will my dog’s pain be managed?
What will my dog’s quality of life be like during and after treatment?
What is the estimated cost of the recommended treatment plan and ongoing care?
What can I do at home to best support my dog during this time?

Conclusion:

At Animal Cancer Care Clinic (ACCC), we are dedicated to providing compassionate and cutting-edge care for dogs with osteosarcoma. Our experienced team will work closely with you to develop a personalized treatment plan focused on managing pain and maximizing your dog’s quality of life. Please do not hesitate to reach out to us with any questions or concerns you may have. We are here to support you and your cherished canine companion through this difficult journey.