Osteosarcoma in dogs is a bone tumor that is cancerous. This malignancy resembles human pediatric osteosarcoma in appearance. Osteosarcomas are tumors that develop from abnormal bone-making and bone-breaking cells (named osteoblasts and osteoclasts, respectively).
Long bones (arms and legs) are the most usually impacted, but jaw, hips, and pelvis bones can also be affected. Non-bony tissues, such as the mammary glands, spleen, liver, and kidneys, can be affected by osteosarcoma. Extraskeletal osteosarcoma is the name for this type of osteosarcoma.
Causes of Osteosarcoma
It’s difficult to say why a particular dog would get this, or any tumor or disease for that matter. Only a small percentage of tumors and malignancies have a single identified etiology. The majority appear to be caused by a complicated combination of risk factors, some of which are environmental in nature and others which are genetic or hereditary.
Osteosarcomas appear to affect large breed dogs more commonly than the small breeds.
Osteosarcomas appear to affect large breed dogs more commonly than small breeds. Reported predisposed breeds include:
- Boxers
- Doberman Pinschers
- Golden Retrievers
- German Shepherd Dogs
- Great Danes
- Great Pyrenees
- Greyhounds
- Irish Setters
- Irish Wolfhounds
- Labrador Retrievers
- Rottweilers
- Saint Bernards
- Weimaraners
Signs of Osteosarcoma in Dogs
Osteosarcoma is excruciatingly painful. Lameness or a noticeable swelling may be seen if your dog has an osteosarcoma of the limb (appendicular osteosarcoma). Because of the pain caused by the tumor on the bone, your dog may become more lethargic, lose appetite, and be hesitant to exercise or play.
“If your dog has an osteosarcoma of the limb, you dog will have a difficult time hiding the pain”
The most common areas for osteosarcomas in dogs are the radius/ulna (above the front knee) and the tibia/fibula (below the hind knee), but osteosarcoma of the digits (toes), femur (above the hind knee), and hip occur as well.
How is Osteosarcoma Diagnosed?
The majority of dogs with osteosarcoma develop limb lameness. Swelling is common where the tumor has grown, and the area will be warm to the touch due to the severe inflammation. X-rays of the area will be taken by your veterinarian. Due to the absence of normal bone tissue, osteosarcomas seem lytic (meaning fragments of bone are gone). Fractures can occur if the bone has become sufficiently weakened.
A fine-needle aspiration can be used to establish a more definitive diagnosis once a lesion has been suspected. This entails suctioning a sample of cells directly from the lesion using a small needle and syringe and depositing them on a microscope slide.
The slide is subsequently examined under a microscope by a veterinary pathologist. This procedure is carried out under anesthesia. A bone biopsy may be necessary if this procedure is not conclusive. In most situations, lytic bone lesions discovered on X-rays are symptomatic of an infectious or malignant condition, and further testing is always advised.
How Does this Cancer Progress?
Osteosarcoma is a very aggressive cancer in dogs. About 90-95 percent of dogs will have micrometastasis at the time of diagnosis, which means the cancer cells have already moved elsewhere and are undetectable.
In dogs with osteosarcoma, staging (looking for potential spread to other parts of the body) is always recommended. Blood tests, urinalysis, X-rays of the lungs, and potentially an abdomen ultrasound are all possible tests. If any lymph nodes are larger or feel abnormal, further sampling may be done to see if there is any spread.
Treatment for Osteosarcoma
The primary goal is to manage the tumor locally if there is no sign of it spreading. Amputation of the afflicted leg is usually required. Though many dog owners are concerned, most dogs recover quickly following amputation. As long as the surgery is a safe and realistic option, it is virtually always chosen.
Surgery is almost always recommended immediately as long as it is a safe and viable option.
Chemotherapy is nearly always pursued post-surgery to help control the disease for as long as possible. Other treatment options may also be available, including certain forms of radiation therapy and alternative therapies.
Is there anything else I should know?
Adequate pain control is of utmost importance. Discuss appropriate pre-and post-operative therapy and pain management plans with your veterinarian or veterinary oncologist.
Read more:
Recent and current clinical trials in canine appendicular osteosarcoma – PMC
NC State Clinical Trial Testing Promising Canine Osteosarcoma Treatment
What do we know about canine osteosarcoma treatment? – review – PMC
Recent Advances in the Discovery of Biomarkers for Canine Osteosarcoma
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