A Pet Owners Guide to Bone Cancer in Dogs: Causes, Symptoms, and Treatment

What is Bone Cancer in Dogs? 

Bone cancer in dogs is a tumor that develops in the bone tissue when the normal bone cells turn into cancer cells. Based on the type of cells that turn into cancerous cells, there are different types of bone cancer in dogs. Common bone tumor examples are osteosarcoma, fibrosarcoma, chondrosarcoma, and hemangiosarcoma.  

Depending on where they start, bone tumors can be classified as primary or secondary bone tumors. A primary tumor is when the tumor starts in the bones. A secondary tumor is when the tumor originates from other parts of the body and then metastasizes (spreads) to the bones. 

Especially in the early stages, the clinical signs and symptoms of bone tumors in pets are non-specific, meaning that the symptoms aren’t specific to cancer. The prognosis depends on several factors, including the tumor type, primary tumor location, tumor severity (benign tumor vs. malignant tumor), and whether appropriate treatment was initiated promptly. 

What is Osteosarcoma in Dogs? 

Canine osteosarcoma is an aggressive form of cancer that develops as a result of the abnormal growth of immature bone cells. Osteosarcoma is the most common type of primary bone cancer. 

Based on different sources, osteosarcoma accounts for between 85% and 95% of all canine cancer cases. Regardless of the exact statistics, it is safe to say that osteosarcoma is one of the most common types of cancer in dogs. The disease is more common in large and giant dog breeds and middle-aged to senior dogs.  

As a primary tumor, osteosarcoma starts in bone tissue, with common sites being the appendicular skeleton(front legs and hind legs), vertebrae, ribs, hips, pelvic bone, and facial bones (jaws). Interestingly, osteosarcoma may affect non-bony tissues. For example, the primary site of the tumor can be in the kidneys, liver, spleen, and mammary glands (extraskeletal osteosarcoma). 

Osteosarcoma in dogs is an aggressive tumor, meaning it spreads quickly and frequently. The lungs and lymph nodes are common locations that osteosarcoma spreads to. Osteosarcoma that metastasizes to the lungs can possibly cause respiratory distress. Sadly, the prognosis for this common type of bone cancer is poor. 

Does Bone Cancer in Dogs Spread Quickly?

Yes, bone cancer in dogs spreads quickly, and it is classified as an aggressive condition with a high metastatic rate. As an aggressive bone cancer, osteosarcoma causes painful bone destruction, resulting in decreased quality of life. In rare cases, some types of canine bone tumors may spread more slowly. 

What Causes Bone Cancer in Dogs?

The exact causes of bone cancer in dogs are unknown. The general rule of thumb is that canine cancer is the result of several risk factors working at the same time. Here are some of the established risk factors for bone cancer in dogs: 

• Genetics. Certain dog breeds are prone to bone cancer. This includes large-breed dogs (Scottish Deerhounds, Golden Retrievers, Irish Setters) and giant breed dogs (Great Danes). Although bone tumors are more common in larger breed dogs, they can also develop in smaller dogs. 
• Age. Like most types of tumors, bone cancer in dogs is more likely to occur in older dogs. This does not mean that puppies and adult dogs cannot develop a cancerous bone mass. However, the incidence is higher in seniors. 
• Environment and Lifestyle. Exposure to certain carcinogens (cancer-causing substances) increases the risk of canine cancer. Also, the dog’s lifestyle, such as nutrition and exercise, may affect tumor onset. 

What are the Signs of Bone Cancer in Dogs? 

The clinical signs and symptoms of bone cancer may vary based on the location of the primary tumor. In general, pet parents can expect the following signs and symptoms: 

• Severe bone pain 
• Various degrees of lameness (for limb tumors) 
• Mass on the dog’s front legs or rear legs
• Neurologic signs, such as difficulty urinating (for spine tumors)   
• Difficulty eating (for jaw tumors) 
• Respiratory distress (for rib tumors)
• Enlarged lymph nodes
• Lethargy and overall weakness 
• Loss of appetite and weight loss  

If your dog is showing some of these signs, you need to seek veterinary help and schedule an appointment. The most common bone cancer in dogs, osteosarcoma on the limbs of dogs, is invasive and spreads quickly. Therefore, time is of the essence for diagnosis and treatment.  

Diagnosing Bone Cancer in Dogs

Veterinarians always start with an initial evaluation of a dog. The process of diagnosing bone cancer in dogs begins with a complete physical examination. Then, based on the findings, the vet will recommend various diagnostic tests. 

For example, the veterinarian will order an x-ray of the affected limbs. The presence of “moth-eaten” bone tissue, which indicates bone destruction, is indicative of osteosarcoma. For a more definitive diagnosis, which includes determining the specific tumor type and stage (size and spread of the tumor), the vet will perform fine-needle aspiration (FNA) or biopsy. An FNA involves using a small, thin needle to take a small sample of bone tissue then analyze the cells in that sample with a microscope. A biopsy involves taking a large tissue sample and analyzing that sample with a microscope.

Sadly, by the time of diagnosis, the osteosarcoma will likely have spread to other parts of the body, usually the lungs. Chest x-rays will reveal useful information that can help determine the best treatment plan. 

Advanced diagnostic tests, such as CT scans may be needed to confirm the diagnosis. 

Finally, to evaluate the dog’s overall health and check for co-existing health issues, the veterinarian will order blood work (complete blood count and biochemistry profile) and a urinalysis.

Based on the results of these tests, your trusted vet may recommend seeking medical advice from a veterinary oncologist for further diagnostic testing or a specialized treatment plan. There are many different cancer treatments, and each dog will need to have an individualized treatment plan.   

How Do You Treat Bone Cancer in Dogs? 

There is no one cancer in dogs treatment. There are various treatment options, and which one is best depends on the individual patient. Talk to a veterinary oncologist about the best option. Let’s take a closer look at some of the most common treatment options for dogs with bone cancer.  

Surgery. Surgical removal, or amputation, of the affected limb, is a viable option in the case of limb osteosarcoma. If cancer has not already metastasized, limb amputation may help to keep cancer from spreading. However, based on the specific tumor location, this surgical procedure is not always possible. Also, amputation may not be possible for older dogs that cannot handle the anesthesia. 

Chemotherapy. When it comes to treating bone cancer in dogs, chemotherapy can be used as adjuvant therapy, meaning that it can be used in combination with other cancer treatment options. For example, chemotherapy can be used to make the tumor small enough for it to be surgically removed. In other cases, chemotherapy may be the only treatment used if other treatment options, such as surgery or radiation, are not possible. 

Radiation Therapy. Radiation therapy is recommended for cases in which the tumor location does not allow surgical removal or if there is not much bone damage. Different types of radiation therapy are available to treat bone tumors in dogs. For example, stereotactic radiation therapy delivers high doses of radiation with extreme precision, sparing the surrounding healthy tissue. Palliative radiation therapy is used to relieve tumor-related discomfort. 

Pain Management. Bone cancer in dogs is a painful disease, meaning it requires proper pain relief. There are different pain medications to relieve bone cancer-related pain. It is advisable to talk to your trusted veterinarian and ask which is best. 

To ensure the best quality of life, your dog with bone cancer may require some additional, holistic treatment options. Today, the most popular holistic remedy is CBD. 

Cannabidiol (CBD) Products. CBD oil is a natural remedy with only a few mild side effects. A recent study has shown that CBD oil could help to decrease the proliferation of cancer cells in several canine cancers, including osteosarcoma. However, much more research must be done before CBD is used as an actual cancer treatment in dogs. CBD can also provide pain relief. We suggest trying CBD products from the Honest Paws Collection. They are made with premium quality and human-grade hemp CBD oil and are straightforward to use. Talk with your veterinarian if you are considering giving your dog CBD while your dog is undergoing cancer treatment.  

New therapies for cancer are constantly emerging. For example, there are many ongoing clinical trials for dogs with cancer at the Flint Animal Cancer Center. Talk to your vet if some of these research studies are a viable option for your pet. 

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What Can I Do to Prevent Bone Cancer in Dogs? 

Wondering how to prevent cancer in dogs? Preventing bone cancer in dogs is a tricky job. This is because its development depends on numerous factors. However, since there are risk factors, there are several things you can do to decrease the dog’s chances of developing bone cancer: 

• Regular Checkups. If you have a large- or giant-breed dog that has a higher risk of bone cancer, be extra diligent about regular veterinary exams. 
• Healthy Lifestyle. Obesity is a risk factor for many canine cancer types. Giving your dog a nutritionally-balanced food and providing proper exercise is an excellent way of keeping your dog healthy. 

With that being said, early detection is vital, but vet checkups can be expensive. Recent bone cancer treatment developments and new therapies are costly as well. This is why it is helpful to invest in a good insurance plan. 

We recommend the OneVet plan. With OneVet, you get 24/7 access to licensed online veterinarians and up to $3,000 in emergency funds. These funds can help defray the cost of bone cancer treatment for your dog.  

How Long Will a Dog Live With Bone Cancer? 

The exact survival time and overall prognosis for dogs with bone cancer depend on several factors, such as tumor type, metastasis rate, and type of treatment.  

Obviously, the prognosis is better when the cancer is diagnosed in its earliest stages. However, in practice, this is not always possible. Namely, osteosarcoma of the limb is aggressive cancer, and by the time of diagnosis, it is already advanced.    

Considering the nature of this aggressive disease, dog owners must be prepared for the worst. If the treatment recommendations are not working, euthanasia might be the best option.  

How Long Can a Dog Live With Untreated Osteosarcoma?

Dogs with untreated osteosarcoma usually do not live for more than two months. Survival time is often longer with treatment, such as chemotherapy and surgery.