Osteosarcoma (bone cancer) is one of the most common tumor types in dogs. It usually develops in middle-aged or older large-breed dogs (although it increasingly occurs in younger dogs aged 2–3 years), especially in breeds such as Saint Bernard, Newfoundland, Great Dane, Pyrenean Mountain Dog, Cane Corso, and Bernese Mountain Dog, and it is more common in males.
Osteosarcoma is a type of tumor that usually originates on the bone surface and then spreads inward into the bone marrow. Unfortunately, the exact cause is still unknown.
Symptoms of osteosarcoma in dogs
The symptoms of bone cancer usually appear near the tumor site. This is typically around the limbs, ankles, and knees, but it can also occur in the ribs or nasal cavity. Symptoms vary depending on the tumor’s location. There may be bone enlargement or visible swelling, joint pain and lameness if the limbs are affected, or sneezing, nosebleeds, and difficulty breathing if the nasal cavity is involved.
Why early detection is important
Many owners mistake early lameness or swelling for an injury and only take their dog to the vet later. However, osteosarcoma spreads extremely quickly, so early diagnosis can be life-saving. The sooner examinations and treatment begin, the better the chances of slowing disease progression and improving the dog’s quality of life.
Treatment of osteosarcoma in dogs
The effectiveness of treatment depends on several factors, including how deep the tumor is located in the bone and whether it has already reached the bone marrow.
The most effective method of treating osteosarcoma is surgical removal of the affected area. Usually, the affected limb must be amputated, although in rare cases, a smaller, local procedure may be sufficient depending on the location and size of the tumor.
The success of surgery mainly depends on whether the dog’s immune system can fight tumor metastasis or recurrence. Simply removing the tumor rarely results in complete recovery, as in 90% of cases the tumor eventually returns, regardless of the surgery’s success.
Chemotherapy often follows surgery, but unfortunately, in the case of osteosarcoma, it is not very effective. Radiation therapy is also used, but mainly to relieve pain if surgery is not possible. However, it is important to understand that surgery, radiation, and chemotherapy alone do not cure cancer.
The body and immune system are what can truly defeat the tumor!
How long can a dog live with osteosarcoma?
The prognosis of osteosarcoma depends on many factors: the tumor’s location, treatment options, and the dog’s overall health. Without surgery and supportive therapy, the average survival time is only a few weeks to 2 months. With amputation, this increases to 3–6 months, and with chemotherapy combined with immunotherapy, it can extend to 9–12 months. While complete recovery is rare, the main goal is pain reduction and quality of life improvement.
The role of immunomodulatory therapy
A strengthened immune system is much less weakened by chemotherapy and radiation, and during recovery it better resists both internal and external infections and pathogens. A healthy immune system recognizes developing tumor cells and responds appropriately, significantly reducing the chance of metastasis and recurrence. Therefore, immunomodulatory therapy is recommended during and after surgery.
Although osteosarcoma usually develops in one place, this tumor type is highly prone to metastasis and recurrence. It is crucial for the body itself to recognize and resist tumor cells effectively.
Our own experience and testing have shown that dogs treated conventionally (surgery, chemotherapy, radiation) combined with some form of immunomodulatory therapy (such as K9 Immunity™, K9 INU®, or similar supplements) achieved significantly better results than with surgery alone.
Osteosarcoma and strengthening the immune system
Supporting the immune system is crucial in all diseases involving immune dysfunction, such as lymphoma, dog brain tumor, mastocytoma, hemangiosarcoma, or mammary tumor. Until the body itself begins to respond to the disease, we can only talk about symptomatic treatment, not true healing.
It is no coincidence that many veterinarians emphasize: although the tumor can be treated, if the immune system is not supported, recovery will not be complete—at best, time can be prolonged.
Since the cost of chemotherapy, radiation, or surgery can be very high, we are often asked whether medicinal mushrooms alone might be sufficient.
Therefore, as far as possible, it is advisable first to reduce the tumor with conventional medical methods—such as surgery. This relieves the immune system and prepares it to work effectively again with targeted immunomodulatory support (e.g., K9 Immunity™, K9 INU®, K9 INUFactor®, K9 INUExtra®). Of course, there are exceptions: we know of several cases where owners relied exclusively on these supplements and the dog still made a full recovery.
Whatever path you take, whatever decision you make, always discuss it with your veterinarian!
Tips for owners: how can you help your dog?
Alongside treatment, everyday care is very important. Provide your dog with a comfortable bed, easy access to water, and a nutritious diet. Always consult your vet about pain management. Love, patience, and a calm environment not only improve your dog’s wellbeing but also strengthen its immune system and resilience.
- Avoid overexertion: limit climbing stairs, jumping, and long walks. Opt for shorter, gentler activities to avoid unnecessary stress on the bones.
- Regular check-ups: since the tumor can progress quickly, veterinary visits are essential to detect recurrence or metastasis in time.
- Immune system support: in addition to diet, give immune-boosting supplements (e.g., medicinal mushrooms, specialized formulas) to help the body fight tumor cells.
The importance of proper diet in dogs with cancer
Cancer is one of the leading causes of death in dogs. Several recent studies confirm that healthy nutrition plays a role in the prevention of cancer. For example, recent publications have shown that many owners switch to more nutritious, energy-dense foods and supplements in order to improve quality of life for dogs diagnosed with cancer. Kramer et al., 2023 – Changes in diet and supplement use in dogs with cancer.
Most dogs are fed kibble based on grains, even though dogs are carnivores. They lack the enzymes needed to break down grains, so digesting carbohydrates is often problematic for them.
As a result, the body either does not get enough nutrients or cannot utilize them properly. In the long term, an inappropriate diet weakens the immune system, which can increase the risk of cancers such as osteosarcoma.
If poor nutrition really contributes to the development of bone cancer in dogs, then conscious feeding becomes even more important. For a dog with cancer, it is not just recommended but almost mandatory. A carefully chosen diet can be one of the most important elements of successful treatment and a better quality of life.
Your dog’s body needs real, easily utilized nutrients to fight the disease. Just because a food is expensive, trendy, or widely recommended does not mean it is the best choice. A conscious, well-considered decision about diet can even save a life.
Read our related articles: Nutrition for dogs with cancer, and the Hungarian version: Read our article in Magyarul.
Risk factors and prevention
The exact cause of osteosarcoma is unknown, but certain factors increase the risk: large and giant breeds, rapid growth, genetic predisposition, and previous bone injuries. While complete prevention is not possible, a proper diet, regular veterinary screenings, immune-boosting supplements, and a balanced lifestyle can help make the dog’s body more resilient.
Frequently asked questions about osteosarcoma in dogs
❓ What is osteosarcoma in dogs?
Osteosarcoma is a malignant tumor that originates from the bone, most often in the limbs, and quickly metastasizes.
❓ What are the symptoms of bone cancer in dogs?
The most common symptoms are lameness, bone swelling, pain, nosebleeds, or sneezing. Symptoms depend on the tumor’s location.
❓ Which dog breeds are prone to osteosarcoma?
Mainly large breeds such as Saint Bernard, Newfoundland, Great Dane, Pyrenean Mountain Dog, Cane Corso, and Bernese Mountain Dog.
❓ How long can a dog live with osteosarcoma?
Without treatment, only a few weeks–2 months. With amputation, 3–6 months, and with combined therapy and immunomodulation, up to 9–12 months.
❓ Can bone cancer in dogs be cured?
Complete recovery is rare. The goal is to reduce pain, slow the disease, and support the immune system for longer survival.
❓ Is amputation recommended for dogs with osteosarcoma?
Amputation is the most common and effective treatment. It reduces pain, relieves the body, and can extend the dog’s life.
❓ What treatment options are available for canine osteosarcoma?
The most common treatment is limb amputation. As additional options, chemotherapy, radiation, and immunomodulatory supplements may also help.
❓ How can I help my dog at home?
Provide a comfortable resting place, gentle exercise, a nutritious diet, and immune-boosting supplements. Regular veterinary check-ups are essential.
For more information, you can read our article on nutrition for dogs with cancer, as well as our overview of tumor symptoms in dogs. In addition, you can learn how medicinal mushrooms can also support cancer treatment, and moreover, you may browse our wide range of immune-boosting supplements for dogs.
More about dog cancers
Important: This article is for informational purposes only and does not replace veterinary examination or treatment. For an accurate diagnosis and the right therapy, always consult your veterinarian.
References:
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- Boston, S. E., Ehrhart, N. P., Dernell, W. S., Lafferty, M. H., Withrow, S. J., & Rao, S. (2006). Evaluation of survival time in dogs with stage III osteosarcoma: 90 cases (1985–2004). Journal of the American Veterinary Medical Association, 228(12), 1905–1908.
- Szewczyk, M., Lechowski, R., & Zabielska, K. (2015). What do we know about canine osteosarcoma treatment? – review. Veterinary Research Communications, 39(1), 61–67.
- Cornell University, College of Veterinary Medicine. (n.d.). Osteosarcoma in dogs. Riney Canine Health Center. Retrieved September 16, 2025, from https://www.vet.cornell.edu/…/osteosarcoma-dogs
- Simpson, S., Dunning, M. D., de Brot, S., Grau-Roma, L., Mongan, N. P., & Rutland, C. S. (2017). Comparative review of human and canine osteosarcoma: morphology, epidemiology, prognosis, treatment and genetics. Acta Veterinaria Scandinavica, 59(1), 71.
- Selvarajah, G. T., Kirpensteijn, J., van Wolferen, M. E., Rao, N. A. S., Fieten, H., & Mol, J. A. (2009). Gene expression profiling of canine osteosarcoma reveals genes associated with short and long survival times. Molecular Cancer, 8, 72.
