Osteosarcoma in dogs is a type of malignant cancer that affects the bones of middle-aged to older dogs. Unfortunately, it is often diagnosed late because it doesn't always cause symptoms in the early stages. By the time most dog owners realize their pet has osteosarcoma, it's usually too late to do anything but provide palliative care. In this article, we will take a closer look at osteosarcoma in dogs and how you can provide your pet with the best possible quality of life if he or she is diagnosed with this condition.
What is osteosarcoma in dogs and how does it develop?
Osteosarcoma (OSA) makes up 85% of all primary bone cancers, making it by far the most common bone tumor in dogs. The median age at which osteosarcomas are diagnosed is 7 years and giant and large breed dogs are more likely to develop osteosarcoma compared to smaller dogs. Common breeds that are affected include rottweiler, Great Dane, St. Bernard, Irish setter, Doberman pinscher, German shepherd, Rhodesian ridgeback, and golden retriever. Given that certain dog breeds are predisposed to osteosarcoma, this suggests there is an underlying genetic component. Typical locations for osteosarcoma to develop in dogs are the proximal humerus and tibia, distal femur, and radius.
What are the symptoms of osteosarcoma in dogs?
The most common symptoms of osteosarcoma in dogs are acute lameness and swelling of the affected leg. These symptoms can be caused by the cancerous cells growing and pushing against the surrounding tissue or because the bone cancer has weakened the bone and made it susceptible to pathological fracture. Other symptoms include fever, reduced appetite, and weight loss.
It is important for dog owners to be aware of these symptoms, as osteosarcoma is often diagnosed late. By the time most owners realize their pet has osteosarcoma, it's usually too late to do anything but provide palliative care. Palliative care aims to control your dog's pain and discomfort and improve his or her quality of life.
How is osteosarcoma in dogs diagnosed?
Osteosarcoma is diagnosed through a combination of supporting clinical findings, imaging, and histopathology (bone biopsy). X-rays can help identify osteosarcoma in its early stages by showing changes to the bone's density or shape. However, osteosarcoma causes osteolytic (destructive) lesions that are not revealed early in the disease course. This is why in some cases, osteosarcoma is initially misdiagnosed as another cause of lameness but is later found to be bone cancer.
How is osteosarcoma in dogs treated, and what are the survival rates?
When considering treatment for canine osteosarcoma, two separate issues must be addressed. The first is a locally destructive, painful bone lesion, and the second is a very high risk of systemic metastasis.
Amputation and survival rates
Amputation of the affected limb is the best way to treat the local disease and the majority of patients tolerate amputations extremely well. Amputation alone, however, has been shown to produce only short-term benefits. Only 10% of dogs survive one year after amputation alone, with the median survival time being 4 months. In most cases, patient death is the result of metastasis to the lungs.
Chemotherapy and survival rates
When systemic chemotherapy is added to amputation, the survival time is significantly increased. When cisplatin is included in the treatment, the median survival time increases to 10-12 months, with approximately 20% of dogs living longer than 2 years.
Radiation therapy
Radiation therapy for affected bones is a reasonable palliative option in most parts of the United States and Canada. In approximately 75% of dogs with OSA, which persists for a median of 2-4 months, radiation therapy in the form of weekly outpatient treatments can be used to provide good pain control.
The key takeaway for how osteosarcoma in dogs is treated is that amputation is the best way to treat the local disease, and when systemic chemotherapy is added to amputation, the survival time is significantly increased.
FAQs
How can you provide your dog with palliative care if he or she has osteosarcoma?
Any dog receiving nonsurgical treatment for osteosarcoma needs aggressive pain management with oral analgesics. Amantadine, gabapentin, and NSAIDs are commonly used as oral analgesics. Due to the risk of pathological fracture, exercise and activity should be limited, especially when on pain medication.
What is the risk of metastasis in osteosarcoma?
A metastatic spread is likely in 80-90% of dogs with osteosarcoma, most commonly to the lungs, even with aggressive local and systemic therapy.
How to prevent osteosarcoma in dogs?
Unfortunately, there are no preventative options available as osteosarcoma is considered a genetic disease.
If your dog's bone cancer has already spread, how long will he or she live on average?
If there is metastasis to the lungs, the average survival time is 6 months.
The article discussed osteosarcoma in dogs, which is a type of aggressive bone cancer that affects the limb of the dog. The cancer is usually diagnosed late, and the main symptom is acute lameness. Treatment options include amputation and chemotherapy, with radiation therapy being a palliative option. Amputation alone has a 10% survival rate, while chemotherapy and radiation therapy increases the survival rate. As with any cancer, early detection is key. If you notice your dog develops a sudden lameness with swelling and pain, please visit your veterinarian ASAP!