What You Should Know About Osteosarcoma (Bone Cancer) In Dogs

Signs & Symptoms of Osteosarcoma in Dogs

The symptoms of osteosarcoma, or bone cancer, in dogs can be subtle. They may include:

• Lameness that doesn’t go away and swelling of the affected bone; these are the most common symptoms when a tumor affects a limb
• Swelling or a mass; this is often the first sign of a tumor in the skull, jaw, or ribs
• Difficulty eating if a tumor affects the jaw
• Neurologic signs, such as seizures or a wobbly gait, with the skull or spinal/vertebral tumors
• Breathing difficulties or lameness with rib tumors
• Loss of appetite and lethargy

Source: ACVS.org

Diagnosis and Staging Osteosarcoma in Dogs

To properly diagnose osteosarcoma, veterinarians run the following diagnostics to come to a determination of the root cause of symptoms:
X-Ray – First, your vet will take an X-ray and perform a physical and orthopedic examination to rule out other causes of lameness.
Biopsy – To obtain a definitive diagnosis and determine the best treatment plan for your dog, any problem areas identified on the X-ray will be biopsied for further analysis.
Other diagnostics – Chest X-rays or a computed tomography (CT) scan, blood tests, and a urinalysis will usually be performed to assess your dog’s overall health and determine if cancer has spread. In over 90% of dogs, the tumor will have already metastasized at the time of diagnosis; and osteosarcoma most commonly spreads to the lungs.²
Advanced CT imaging – An advanced CT is often recommended for osteosarcoma tumors of the limbs. This type of scan provides more detailed imagery of the tumor allowing a veterinary surgeon to ascertain if surgery is possible and how elaborate the surgery will need to be in order to achieve a favorable outcome.

RELATED: Osteosarcoma Data Sheet 

How Does Bone Cancer Usually Progress?

Osteosarcoma in dogs is an aggressive form of bone cancer that progresses quickly. Often the first clinical sign will be lameness or a firm bony mass may be felt protruding from the bone. This cancer can metastasize (spread) to other areas of the body if left untreated. Once diagnosed, it is recommended to seek treatment as soon as possible in order to slow down the spread of the disease and reduce pain for your dog. Surgery (amputation) is typically the first line of defense, followed by chemotherapy however for some cases, radiation therapy can take the place of amputation, thereby preserving the use of the dog’s leg. Radiation can be combined with chemotherapy in an attempt to prolong the prognosis even further.

Treatment Options for Osteosarcoma in Dogs

Osteosarcoma has a variety of treatments – and each treatment depends on your dog’s individual diagnosis. Bone cancer can be treated in any of the following ways:
Amputation – Because osteosarcoma tumors are so aggressive, amputating the affected limb followed by chemotherapy to treat metastasis is the most common treatment. While amputation isn’t the right option for all pets, otherwise healthy dogs can function quite well with three legs.
Limb-sparing surgery—This surgery, in which the tumor is removed and the bone is replaced with another bone (either from your pet or from a bone bank), may be an option depending on the tumor’s location and whether it is relatively small at the time of diagnosis. The complication rate for this type of surgery, particularly infection, is relatively high, however.
Stereotactic radiation – When surgery isn’t an option due to tumor location, stereotactic radiation (SRS/SRT) can be beneficial. It can also be an alternative to amputation for dogs in which the osteosarcoma hasn’t destroyed a great deal of bone. This advanced, highly accurate type of radiation therapy focuses high doses of radiation to damage and kill osteosarcoma cells. Follow-up chemotherapy is still necessary.

Stereotactic radiation has a number of advantages over other treatment types. The main advantage of SRS/SRT is that it delivers high doses of radiation with sub-millimeter precision. A few advantage of SRS/SRT over other types of cancer treatment include:

• Precision – Maximum damage to the tumor and there is minimal damage to healthy nearby tissues. Therefore SRS/SRT affords us the ability to treat tumors that were previously considered untreatable with radiation due to this level of precision.
• Fewer treatments – Fewer treatment sessions compared to conventionally fractionated radiation therapy (CFRT). With stereotactic radiation, patients require only 1-3 sessions total, which means fewer anesthetic events, less risk, and less disruption to your schedule.
• Faster recovery – SRS/SRT offers the potential for a quicker recovery with fewer side effects than other treatments.

Sometimes palliative treatment is recommended. Palliative treatment aims to make your pet more comfortable but doesn’t provide a cure, and can include conventional radiation therapy and drugs to reduce pain. PetCure Oncology’s radiation oncologists are experienced using SRS/SRT to treat dogs with all types of osteosarcoma.

What Happens After Radiation Treatment?

The recovery process from radiation therapy for osteosarcoma can vary depending on the dog and their individual circumstances. The most common side effects are a sunburn-like effect on the skin in the treatment field, fur loss in that area with white fur regrowth. Additionally, it is vital to keep your dog quiet on that affected limb (no running, no jumping, no excitement) while that leg is healing as there is an increased risk for fracture. It is important to make sure your dog gets plenty of rest and receives enough quality nutrition. Pain medications may be prescribed by your veterinarian if needed. Because osteosarcoma is an aggressive cancer, you will want to work closely with your veterinarian to monitor for signs of recurrence or progression of the cancer including metastasis (cancer that has spread). Early detection is critical for ensuring successful treatment outcomes.

Osteosarcoma in Dogs: Life Expectancy, Survival, and Prognosis

The prognosis for pets with osteosarcoma depends on the severity and spread of the disease and on the treatment you choose. Dogs with limb osteosarcoma that receive SRS and chemotherapy have a median survival time of about one year, similar to the survival time for dogs treated with amputation and chemotherapy. Up to 16–28% of dogs are alive at two years.³ The median survival time for dogs with amputation alone is about three months.⁴

Meet Our Osteosarcoma Pet Heroes

Here are a few our inspiring Pet Heroes that have fought bone cancer. We invite you to read their stories. If your pet was diagnosed with osteosarcoma, contact the nearest PetCure Oncology location near you. You can also ontact our Pet Advocates at 833-738-4376. Our team members are ready to help answer your questions.

• Pet Hero: Rufus the Big Lovable Mastiff Mix
• Pet Hero: Mandie the Therapy Dog Inspires Others
• Pet Hero: Sundance Walks Again Following Cancer Treatment (chondrosarcoma)

^REFERENCES
1 “Bone tumors in cats and dogs,” acvs.org
² “Osteosarcoma in dogs and cats,” petcarerx.com
³ “Osteosarcoma: when amputation is not an option, part 2,” dogcancerblog.com, “Bone tumors in cats and dogs,” acvs.org
⁴ “Fact sheets: stereotactic radiosurgery,” vetmed.ucdavis.edu