- Osteosarcoma in dogs: Guidelines for diagnosis, treatment, and prognosis of the appendicular skeleton
- 1. Introduction
- 2. Epidemiology and etiology
- 3. Clinical presentation
- 4. Diagnostic procedures
- 5. Staging & Prognostic Classification
- 6. Treatment options in detail
- 7. Palliative medicine & pain management
- 8. Prognostic factors
- 9. Transfer: When and where?
- FAQ on osteosarcoma in dogs
- 10. Conclusion & Outlook
- 11. Summary: Osteosarcoma in dogs – symptoms, diagnosis, treatment and prognosis
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Osteosarcoma in dogs: Guidelines for diagnosis, treatment, and prognosis of the appendicular skeleton
A comprehensive overview for veterinarians, veterinary students and informed dog owners
1. Introduction
Osteosarcoma in dogs is the most common primary bone tumor in this species and presents veterinarians worldwide with significant clinical challenges. Approximately 85% of all diagnosed bone tumors in dogs are osteosarcomas. Despite decades of research, key questions regarding their pathogenesis, optimal treatment, and long-term survival prognosis remain unanswered.
This guideline is based on the current state of the literature and was developed by an international group of experts. It aims to support veterinary professionals in evidence-based decision-making, particularly in the management of appendicular osteosarcomas in dogs.
(C) From the study attached below.
2. Epidemiology and etiology
Racial predisposition
Some dog breeds are particularly susceptible to osteosarcoma. For example, the Scottish Deerhound is known to have a more than 100-fold increased risk, while Leonbergers, Great Danes, Rottweilers, and Greyhounds are also at high risk. Other breeds commonly affected include Irish Wolfhounds, St. Bernards, Labrador Retrievers, Golden Retrievers, Boxers, Doberman Pinschers, and German Shepherds.
Risk factors
Size and weight play a crucial role: Large to giant dog breeds are disproportionately affected. If a dog has an above-average weight for its breed, the risk of osteosarcoma increases by 1.65 times. The disease most commonly occurs in animals between the ages of 7 and 9, but can also be diagnosed in young dogs as young as 18 to 24 months old. Genetic mutations—particularly in genes such as TP53, MYC, PTEN, RUNX2 , and DLG2 —are also associated with the development of the disease. Previous fractures or bone infections (osteomyelitis) are considered possible additional risk factors for the later development of osteosarcoma.
3. Clinical presentation
Symptoms
The most common clinical signs are initially intermittent, later persistent lameness, as well as localized pain, usually occurring in the metaphyseal region of the long bones. Conspicuous swelling over the affected bone is also a classic symptom. In about 3% of cases, a pathological fracture, i.e., a bone fracture without external trauma, can occur. In later stages, affected dogs often also exhibit systemic symptoms such as loss of appetite, lethargy, and weight loss.
Unusual presentations
In rarer cases, osteosarcoma in dogs can present with paraneoplastic syndromes, such as hypertrophic osteopathy associated with thoracic metastases. Metastases can also affect the lungs, other bones, skin, or lymph nodes.
4. Diagnostic procedures
Imaging procedures
In many cases, X-ray diagnostics already provide typical indications of osteosarcoma: Classic features include the so-called "sunburst" pattern, the Codman triangle, and osteolytic and osteoblastic changes. Accompanying soft tissue swelling is usually also present. Joint infiltration is rare, except in the region of the femoral head.
CT and MRI enable a much more precise assessment of tumor extent, evaluation of fracture risk, and precise surgical or radiotherapy planning.
Cytology (fine needle aspiration, FNA)
Fine-needle aspiration offers a rapid, minimally invasive method for cytological assessment. Its sensitivity is 70–97%, and specificity can reach up to 100%. Since general anesthesia is not required for sample collection, this method is particularly suitable for unstable patients. However, precise subtyping is not possible using cytology alone.
biopsy
For a reliable diagnosis, a core biopsy, such as a Jamshidi needle, is recommended. This allows for detailed histological characterization of the tumor. If possible, the center of the tumor should be biopsied, not the peripheral area. Risks include pathological fractures and the potential spread of tumor cells.
Laboratory diagnostics
Certain blood values, particularly elevated alkaline phosphatase (ALP), correlate with a worse prognosis. Immunological profiles often indicate systemic inflammation, and high PTHR1 expression is also associated with shorter survival.
5. Staging & Prognostic Classification
Comprehensive staging includes an orthopedic examination with targeted palpation, supplemented by lung imaging—ideally a CT scan or at least an X-ray in three projections. A cytological examination of the regional lymph nodes provides additional information. If metastases are suspected, the use of nuclear medicine techniques such as SPECT or PET should be considered.
The modified Enneking staging system distinguishes three main stages:
Stage 1 refers to low-grade tumors without metastases.
Stage 2 comprises high-grade tumors, also without metastases—this is the most common stage of the disease at diagnosis.
Stage 3 occurs when metastases are detected, for example, in the lungs, lymph nodes, or other bones.
micrometastatic disease is already present in over 90% of patients .
6. Treatment options in detail
6.1. Surgical treatment
Amputation of the affected limb remains the gold standard. It provides immediate pain relief in most cases and is well tolerated even in large breeds. Median survival without subsequent chemotherapy is approximately 3–4 months .
As an alternative to amputation, the so-called limb-sparing procedure is available, for example, for tumors in the distal radius. However, this procedure is associated with a high complication rate, particularly infections (up to 78%), implant failure, and local recurrence. Survival is comparable to that after amputation.
In selected cases metastasectomy , the surgical removal of lung metastases, can be performed. In patients with a maximum of two lesions and stable general condition, this can extend survival to up to 255 days.
6.2. Radiotherapy
Stereotactic radiotherapy (SBRT) is a modern form of high-precision radiotherapy. It delivers high doses in a few sessions, allowing for significant pain reduction. However, there is a fracture risk of up to 41%. Median survival is 233–346 days. Careful CT planning is essential.
Hypofractionation is a suitable palliative measure . In combination with zoledronate, the risk of fractures can potentially be reduced. This method is particularly useful in inoperable patients or those who refuse amputation.
6.3 Chemotherapy
Adjuvant chemotherapy , i.e., administered after surgery, is essential for controlling micrometastatic disease. Carboplatin is considered the first choice due to its good tolerability. Doxorubicin is highly effective but potentially cardiotoxic. Cisplatin requires intensive fluid resuscitation due to its nephrotoxic properties.
Treatment typically consists of 4–6 cycles, spaced 2–3 weeks apart. Combination protocols have not yet offered a significant survival benefit. In combination with amputation, survival can be extended to 8–14 months. The 1-year survival rate is approximately 40%, and the 2-year rate is approximately 20%.
6.4. Immunotherapy
L-MTP-PE , a liposomal peptide that can improve survival, has been previously considered successful Listeria and HER2 vaccines , checkpoint inhibitors such as Gilvetmab, adoptive T-cell therapies with IL-2 , anti-CSPG4 DNA vaccines, as well as oncolytic virotherapies (e.g., with VSV) and inhaled IL-15 . These therapies are considered promising but are currently limited to specialized centers and trials.
7. Palliative medicine & pain management
Effective pain management is crucial osteosarcomas in dogs COX-2 inhibitors such as firocoxib or robenacoxib are used, supplemented by opioids such as buprenorphine or fentanyl patches. Gabapentin and amantadine provide support for neuropathic pain. Anti-NGF antibodies such as bedinvetmab and aminobisphosphonates (zoledronate, pamidronate) complement palliative therapy.
8. Prognostic factors
A poor prognosis is associated with an elevated ALP level, a tumor in the proximal humerus, a body weight above 40 kg, a high histological grade (grade III), a high mitotic index, and proven lymph node or lung metastases.
In contrast, the prognosis is more favorable if the tumor has a fibroblastic subtype, is smaller than 7 cm, the body weight is less than 40 kg or – paradoxically – a postoperative wound infection occurs after limb-sparing surgery.
9. Transfer: When and where?
Referral to a specialized clinic is always advisable when complex diagnostic procedures such as CT, PET, or biopsies are necessary, when limb-sparing surgery is being considered, or when access to innovative therapies such as SBRT or immunotherapy is required. The close collaboration between surgery and oncology also supports referral.
FAQ on osteosarcoma in dogs
❓ 1. What is osteosarcoma in dogs and why is it so dangerous?
Osteosarcoma in dogs is a malignant, highly aggressive tumor that originates from bone-forming cells (osteoblasts). It is the most common form of primary bone tumor in dogs and accounts for around 85% of all bone tumors . Osteosarcoma mostly affects the long bones of the limbs – the so-called appendicular skeleton – particularly the distal radius, proximal humerus, distal femur and proximal tibia.
The danger of osteosarcoma lies in its high local aggressiveness and early metastasis . At the time of diagnosis, over 90% of affected dogs already have microscopic metastases , which are usually located in the lungs, but can also be in other bones or lymph nodes. These metastases are usually not visible on imaging at this stage, which further underlines the importance of systemic therapy .
Another risk factor is the local destructive power of the tumor. Not only does it cause pain, but it also weakens the affected bone to such an extent that pathological fractures can occur—bone fractures that occur without external force.
Overall, osteosarcoma in dogs is considered a very serious oncological emergency that requires prompt action, thorough diagnostics, and coordinated multimodal treatment.
❓ 2. What treatment options are available for osteosarcoma and how do they affect life expectancy?
The treatment of osteosarcoma in dogs is complex and requires a combination of different therapeutic methods – so-called multimodal therapy . The goal is to both control the primary tumor locally and contain systemic metastases . There are essentially four proven treatment approaches:
Surgical amputation :
The complete removal of the affected limb is currently the most effective method for relieving tumor pain and eliminating the risk of fracture. Many owners are afraid of amputation, but the reality shows that dogs – even large breeds – cope very well with three legs . Without additional therapy, the median survival time is around 3 to 5 months .
Adjuvant chemotherapy :
Since almost all osteosarcoma patients already have metastases in the body, chemotherapy is strongly recommended . The use of drugs such as carboplatin or doxorubicin after amputation increases the median survival time to 8 to 14 months , with some dogs surviving for more than two years .
Radiotherapy (SBRT) :
For dogs for whom amputation is not possible or is refused, stereotactic radiotherapy is an alternative. It offers excellent pain reduction and, in combination with chemotherapy, can prolong survival to a similar extent to amputation. However, the risk of fractures remains.
Immunotherapy (experimental) :
New approaches using checkpoint inhibitors , vaccines or adoptive T-cell therapies offer promising future prospects but are currently only available in studies or specialized centers.
Ultimately, life expectancy depends largely on the chosen therapy, the general condition of the dog, the location of the tumor and the presence of metastases. Dogs that receive a combination of local and systemic therapy now have a realistic chance of a good year with a high quality of life .
❓ 3. How can I detect osteosarcoma in dogs early? Are there warning signs?
Osteosarcoma in dogs often develops gradually but shows some typical warning signs that may indicate the disease - particularly in large breed dogs that are middle-aged to older. The most common early symptoms are:
Lameness that either comes on suddenly or gets worse over days/weeks
Localized swelling on a bone in the limb
Pain when walking , climbing stairs or even when petting
A protective posture or refusal to move
In some cases: Sudden bone break without trauma (pathological fracture)
These symptoms can initially point to harmless causes such as sprains, arthritis or bruises - this is precisely what makes early detection difficult. Many dogs are mistakenly given painkillers or anti-inflammatories in the initial stages, which improves symptoms in the short term but delays diagnosis.
A particularly important warning sign is if a dog initially limps, then appears to recover and then shortly afterwards limps again - usually more severely than before . This indicates that the tumor is progressing, while painkillers only mask the symptoms.
If a veterinarian or owner detects these signs—especially in a predisposed breed— an X-ray should be taken immediately . This is the only way to detect osteosarcoma with a high degree of probability at an early stage. Early diagnosis significantly improves the prognosis.
❓ 4. What is a dog's quality of life after an amputation? Can large dogs live with three legs?
Many dog owners understandably have great concerns about amputation – especially with large breeds. But practice shows time and again: Most dogs – even large and heavy ones – cope excellently with three legs .
Of course, they require a period of rehabilitation and support immediately after the operation. But just a few days after the amputation, many dogs show significant improvements in their general behavior. The biggest advantage is that the pain from the tumor disappears immediately , which is reflected in a visibly improved sense of well-being and increased activity.
Studies and clinical experience show that amputated dogs:
Can walk, run and play
without problems again Climb stairs or jump into the car
a similar zest for life and mobility to before
any psychological damage (which often occurs in humans)
Of course, individual fitness, weight and any pre-existing medical conditions play a role. But older or overweight dogs almost always benefit from amputation too – especially if the tumor is causing severe pain.
For many owners, the moment their dog walks happily or wags its tail for the first time after the amputation is proof that they made the right decision. Fear is understandable, but quality of life means freedom from pain – not the number of legs .
❓ 5. How much does it cost to treat osteosarcoma in dogs, and is it worth the investment?
The costs for treating osteosarcoma in dogs can vary greatly depending on the type of therapy, region, and veterinary clinic. A rough overview:
Type of treatment
Cost range (estimated)
X-ray + biopsy
€300–700
CT or MRI
€500–1,500
Amputation
€1,000–2,500
Chemotherapy (4–6 cycles)
€1,500–3,000
Radiotherapy (SBRT)
€2,500–5,000
Palliative care
€100–300
A complete, curative treatment with amputation and adjuvant chemotherapy usually costs €3,000–6,000 . If radiotherapy or immunotherapy is also used, the cost can be significantly higher.
Now for the crucial question: Is this investment worth it? The answer depends on various factors:
Quality of life: Therapy cannot cure the disease, but months of good life .
Lifespan gain: Without treatment, 3–5 months; with therapy, up to 14 months or longer.
Emotional component: For many owners, every pain-free week with their pet is priceless.
Additionally, there are options for pet health insurance or surgical insurance —some of which even cover cancer treatments.
If you act early, your dog has a real chance of a lifetime with quality of life —and that's a value many owners value more highly than any sum in euros.
10. Conclusion & Outlook
Osteosarcoma in dogs is one of the most aggressive neoplastic diseases of the skeleton. Thanks to modern diagnostics, multimodal treatment concepts, and interdisciplinary collaboration, the survival time of affected dogs can be significantly extended—often with a good quality of life.
The key to treatment success lies in early diagnosis , sound staging and individual therapy planning – ideally in close coordination with specialised veterinary clinics.
11. Summary: Osteosarcoma in dogs – symptoms, diagnosis, treatment and prognosis
Osteosarcoma in dogs is the most common form of bone cancer and primarily affects the appendicular skeleton , i.e., the limbs. Approximately 85% of all primary bone tumors in dogs fall into this category. Osteosarcoma in dogs is considered particularly aggressive because it grows destructively locally and metastasizes early to other organs—especially the lungs.
The causes of osteosarcoma in dogs are varied. Large dog breeds such as Rottweilers, Great Danes, and Irish Wolfhounds are particularly at increased risk. Genetic factors, high body weight, early neutering, and possibly previous bone injuries or fractures also play a role.
Dogs with osteosarcoma initially display nonspecific symptoms. Typically, a sudden or gradual lameness develops, which initially appears treatable with painkillers. Swelling over the affected bone and increasing sensitivity to pain are classic warning signs. It is especially dangerous if osteosarcoma in dogs is only discovered after an affected bone has fractured – such pathological fractures usually indicate a far advanced stage of the disease.
Diagnosing osteosarcoma in dogs primarily involves an X-ray. Typical features—such as osteolysis, sunburst pattern, or Codman's triangle—often allow for a tentative diagnosis. Imaging is supplemented by fine needle aspiration (FNA) or biopsy for histological confirmation.
An important step in the assessment of osteosarcoma in dogs is staging, i.e., determining the tumor stage. CT scans, chest x-rays, and, if necessary, scintigraphy are used to determine whether metastases are present. Even if no metastases are detected, micrometastases assumed in over 90% of cases, which is why systemic treatment is necessary.
Treatment of osteosarcoma in dogs usually requires a multimodal approach. Amputation of the affected limb is considered the standard procedure for local tumor control. It provides immediate pain relief and reduces the risk of fracture. Contrary to many fears, dogs, even large breeds, usually cope excellently with three legs.
Alternatively , limb-sparing surgeries be performed to preserve the limb, especially for tumors in the distal radius. However, these procedures carry an increased risk of infection and implant failure. For inoperable cases, stereotactic radiotherapy (SBRT) is a suitable option—a modern, precise radiation therapy method that also contributes to pain control.
Another important component of treatment for osteosarcoma in dogs is chemotherapy. Because the risk of systemic metastases is high, adjuvant chemotherapy with carboplatin or doxorubicin has been shown to improve survival. Concomitant systemic therapy is also standard in limb-sparing or SBRT.
For advanced cases or when curative therapy is not possible, palliative measures are used. Palliative care for osteosarcoma in dogs includes pain medication (e.g., NSAIDs, opioids), bisphosphonates to inhibit bone destruction, and, if necessary, radiation therapy for pain relief.
The prognosis for osteosarcoma in dogs depends on many factors. Without treatment, survival is usually less than five months. With amputation and chemotherapy, this can be increased to 10 to 14 months. Some dogs even survive two years or longer—especially with favorable tumor locations, low ALP levels, and no metastases.
New therapeutic approaches such as immunotherapies are increasingly being used. Studies on PD-1 inhibitors, vaccines, and oncolytic viruses are showing initial success, but are currently mostly limited to specialized veterinary clinics. In the future, there are signs that osteosarcoma in dogs can be treated even more specifically through personalized therapies.
Particular attention should be paid to pain management. Osteosarcoma in dogs causes intense pain, which can be both somatic and neuropathic. A combination of COX-2 inhibitors, gabapentin, amantadine, and, if appropriate, anti-NGF antibodies (e.g., bedinvetmab) is common practice today.
Overall, osteosarcoma in dogs a very serious disease – but not hopeless. Early diagnosis, targeted therapy, and good palliative care can give many dogs a longer lifespan and a better quality of life. The emotional burden for owners is understandable, but opting for effective treatment – including amputation – is often the best option for the animal.
Conclusion: Osteosarcoma in dogs is a challenge, but it is easily treatable with modern veterinary medicine. With the right combination of surgery, chemotherapy, and pain management, many animals can live long, pain-free lives.
Study underlying this article: study here
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