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

What Are the Signs of Osteosarcoma in Dogs?

Osteosarcoma can occur in any bone, but in dogs, it most often develops in the long bones of the limbs – particularly near the shoulder, wrist, and knee joints. The disease is highly aggressive and prone to spreading to other parts of the body. If you notice signs such as lameness, swelling, or pain that do not resolve, it is important to contact a board-certified veterinary oncologist as soon as possible. A specialist can perform a full examination, discuss your concerns, and recommend next steps in diagnosis and treatment.

Source: ACVS.org

What Causes Osteosarcoma in Dogs?

Osteosarcoma, or bone cancer, is the most common type of bone tumor diagnosed in dogs and can occur at any age. The disease is often painful and progresses rapidly. While the exact cause is unknown, research suggests that both genetic and environmental factors play a role. Large and giant breeds – such as Rottweilers, Great Danes, Saint Bernards, Greyhounds, and German Shepherds – are at higher risk.

Osteosarcoma can occasionally develop in bones that have experienced previous trauma, including old fractures, bone infections (osteomyelitis), or sites that have received radiation therapy. Some studies have also linked toxin exposure to increased risk.

Although there is no proven way to prevent osteosarcoma, regular veterinary check-ups can help detect changes early, improving the chance of successful treatment.

Signs and Symptoms of Osteosarcoma in Dogs

The early signs of osteosarcoma in dogs can be easy to miss at first. Because this cancer often begins deep within the bone, visible changes may appear only after the disease has progressed. Watch for these common symptoms:

• Persistent lameness or limping that does not improve with rest or medication
• Swelling or a firm mass on the affected limb – often near the shoulder, wrist, or knee
• Swelling or a lump on the jaw, skull, or ribs, which may be the first noticeable sign in those locations
• Difficulty eating or chewing if the tumor affects the jaw
• Neurologic changes, such as seizures, head tilting, or a wobbly gait, if the tumor involves the skull or spine
• Breathing difficulties or lameness if the ribs are affected
• Loss of appetite, fatigue, or general lethargy as the disease progresses

Source: American College of Veterinary Surgeons (ACVS)

How Is Osteosarcoma Diagnosed and Staged in Dogs?

Accurate diagnosis and staging are essential to confirm osteosarcoma and determine how far the disease has progressed. Your veterinarian or a veterinary oncologist may recommend the following tests:

• X-rays: Initial imaging helps identify bone lesions and rule out other causes of pain or lameness.
• Physical and orthopedic exam: Used to evaluate pain, swelling, and mobility in the affected limb.
• Biopsy: A small bone sample confirms whether the lesion is osteosarcoma and guides treatment planning.
• Staging tests: These often include chest X-rays or a CT scan, bloodwork, and a urinalysis to check overall health and look for metastasis (spread of cancer) – most commonly to the lungs.² Research shows that more than 90 percent of dogs have microscopic metastasis at the time of diagnosis.
• Advanced CT imaging: High-resolution CT scans are frequently used for limb tumors. They help surgeons evaluate the extent of the tumor and plan surgery with the greatest chance of removing all cancerous tissue.

How Fast Does Osteosarcoma Progress in Dogs?

Osteosarcoma tends to advance quickly in most dogs, often starting with lameness, pain, or a hard lump near the affected bone. Because the disease is so aggressive, it can metastasize (spread) to the lungs or other bones due to its aggressive nature.

Acting quickly after diagnosis gives pets the best chance of staying comfortable for longer. Amputation (surgery) is usually the first treatment step, followed by chemotherapy to manage microscopic cancer cells. In certain cases, stereotactic radiation therapy (SRS/SRT) can help control the tumor while avoiding amputation and keeping the leg functional. Therefore, a combination of radiation and chemotherapy may further support a pet’s longevity and comfort.

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 advantages 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 and 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.

What Are the Treatment Options for Osteosarcoma in Dogs?

Treatment for osteosarcoma varies for each dog and depends on the tumor’s location, stage, and overall health. The primary goals are to relieve pain, slow or stop the cancer from spreading, and help maintain your dog’s comfort and daily mobility. Common treatment paths include:

Surgery (amputation): Amputation is the most widely used and effective first-line treatment. Removing the affected limb eliminates the painful tumor and, when followed by chemotherapy, helps reduce the likelihood of metastasis. Most dogs adapt remarkably well to life after an amputation, showing great resilience with only three legs.

Limb-sparing surgery: In select cases, surgeons can remove the tumor while keeping the leg functional by replacing the diseased section of bone with a bone graft or implant. Because this procedure carries a higher chance of complications, especially infection, it is typically limited to specific cases treated at advanced centers.

Stereotactic radiation therapy (SRS/SRT): For dogs that are not candidates for surgery, or when owners wish to avoid amputation, SRS/SRT provides a precise, non-invasive alternative. This advanced radiation technique focuses treatment directly on the tumor with sub-millimeter accuracy, minimizing damage to nearby tissue. Chemotherapy is generally added afterward to manage cancer cells that may have spread.

Advantages of SRS/SRT compared with traditional radiation

• Targeted precision: Concentrates radiation on the tumor while protecting surrounding tissue.
• Fewer sessions required: Only one to three treatments instead of multiple weeks of conventional therapy, which means fewer anesthetic events and less disruption for your pet.
• Faster recovery: Most patients return to normal activity quickly and experience fewer side effects.
• Palliative approach when needed: If a cure is not possible, pain control options such as conventional radiation and medication can help pets stay comfortable and maintain a good quality of life. PetCure Oncology’s board-certified radiation oncologists have extensive experience using SRS/SRT to treat osteosarcoma and improve comfort for as long as possible.

What to Expect After Radiation Treatment for Osteosarcoma in Dogs

Recovery after radiation therapy can vary based on your dog’s age, overall health, and the extent of the disease. The most common side effects include mild skin irritation similar to sunburn, fur loss in the treated area, and white hair regrowth.

While the bone heals, it is important to limit activity on the treated limb – no running, jumping, or rough play – since the area is more prone to fracture during recovery. Your veterinary team may prescribe pain medication or anti-inflammatory drugs to keep your pet comfortable and support healing.

Maintaining good nutrition and rest also helps recovery. Because osteosarcoma can be aggressive, follow-up exams and imaging are essential to watch for signs of recurrence or spread (metastasis). Staying in close contact with your veterinary oncologist gives your dog the best chance for long-term comfort and quality of life.

Osteosarcoma in Dogs: Life Expectancy, Survival, and Prognosis

The prognosis for dogs with osteosarcoma depends on how advanced the disease is at diagnosis and which treatments are pursued. Dogs that receive stereotactic radiation therapy (SRS/SRT) combined with chemotherapy have a median survival time of about one year, similar to outcomes seen with amputation and chemotherapy. About 16-28 percent of dogs live for two years³ or longer following treatment.

Dogs treated with amputation alone oftentimes have a shorter survival time of around three to four months⁴, as most cases already include microscopic metastasis at the time of diagnosis.

Factors that can influence prognosis

• The location and size of the tumor
• Whether cancer has spread (metastasized) to the lungs or other bones
• The dog’s age, weight, and overall health
• The treatment approach chosen and how early therapy begins

Every case is different, but with prompt and thorough care, many dogs can have a good quality of life for considerable periods after being diagnosed.

Meet Our Osteosarcoma Pet Heroes

Meet some of our inspiring Pet Heroes who have faced bone cancer with courage and strength. Their stories offer hope to families navigating an osteosarcoma diagnosis.

If your pet has been diagnosed with osteosarcoma, we invite you to reach out to your nearest PetCure Oncology location or speak with one of our Pet Advocates at 833-768-0240. Our compassionate team is here to answer your questions and help guide you through next steps in your pet’s care.

• Rufus the Big Lovable Mastiff Mix
• Mandie the Therapy Dog Who Inspires Others
• Sundance Walks Again Following Cancer Treatment (Chondrosarcoma)

Common Questions About Osteosarcoma in Dogs

Can bone cancer in dogs be treated without amputation?

Yes, in some cases, dogs with osteosarcoma can be treated without amputation. Advanced radiation techniques, such as stereotactic radiation therapy (SRS/SRT), can target the tumor with sub-millimeter precision while preserving the limb. This approach helps control pain, limit tumor growth, and maintain mobility for dogs that may not be good candidates for surgery.

Can radiation therapy help dogs with osteosarcoma?

Yes. Radiation therapy can be an effective part of osteosarcoma treatment by relieving pain and helping control the tumor locally. SRS/SRT, an advanced form of radiation available at PetCure Oncology, delivers high dose radiation directly to the tumor while at the same time sparing normal tissue, usually in just one to three sessions. It is often combined with chemotherapy to help manage microscopic cancer cells that may have spread elsewhere, such as to the lungs.

How does radiation therapy compare to amputation for osteosarcoma?

Both radiation therapy and amputation can help dogs live longer, more comfortable lives. Amputation removes the primary tumor, while stereotactic radiation therapy (SRS/SRT) offers a non-surgical alternative that can spare the limb in certain cases. The most appropriate approach depends on factors including the size of the tumor, its location, and your dog’s overall health, all of which can be discussed during a consultation with a veterinary oncologist.

How long can a dog live with osteosarcoma after treatment?

Survival time varies based on how advanced the cancer is and which treatments are used. Dogs treated with SRS/SRT and chemotherapy often live around a year or longer, with some surviving two years or more. Every case is different, but early diagnosis and specialized treatment can improve your dog’s quality of life, comfort, and longevity.

What are the side effects of radiation therapy for osteosarcoma in dogs?

Most dogs tolerate radiation therapy very well. Temporary effects can include mild skin irritation, fur loss, or white hair regrowth in the treated area. Serious side effects are rare, and the precision of SRS/SRT greatly reduces the risk of damaging surrounding tissues. Your veterinary team will discuss how to keep your pet comfortable throughout recovery.

How do I know if my dog is a candidate for advanced radiation treatment?

Eligibility depends on a variety of factors like the tumor’s location, how much of the bone is affected, and your dog’s overall health. Dogs that cannot undergo surgery, or families that prefer to avoid amputation, may benefit from SRS/SRT. A consultation with a PetCure Oncology radiation oncologist can help determine whether this treatment is the right fit for your pet.

Questions about your pet’s diagnosis? Start by speaking with a Pet Advocate at 833-467-2836 or request an appointment online.

^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