BONE TUMORS

WHAT ARE THE MOST COMMON BONE TUMORS IN SMALL ANIMALS

The most common bone tumor in dogs is osteosarcoma, being a very aggressive tumor with 100% metastatic rate. Unlike the canine population, osteosarcoma in cat can be curative due to its less aggressive behavior.

Less common bone tumors are hemangi-osarcoma, fibro-sarcoma, and chondrosarcoma.

ARE THERE PREDISPOSING FACTORS FOR BONE TUMOR DEVELOPMENT?

Most often bone tumors develop spontaneously without any predisposing factors. However, there are bone tumors that have developed where bone trauma / disease occurred such as after old fractures, joint replacement and fracture repair (associated with implant). Additionally, there are breeds that have a genetic predisposition for osteosarcoma as Scottish hounds, and large breed dogs like Rottweilers.

HOW DO I KNOW IF MY DOG HAS BONE CANCER?

The most common complaint of bone tumor is lameness, and swelling of the tissue around the affected bone. The pain is associated with micro-fracture of the bone involved and eventually the tumor will progress to a complete fracture. To diagnose bone cancer, radiographs and biopsy (obtain sample) should be performed to rule out other causes of bone disease like bone infection (fungal, bacterial etc). Additionally, a full body scan should be recommended to determine if the cancer has spread.

WHAT IS THE TREATMENT FOR BONE CANCER? 

‚Äč Limb amputation, limb spare, radiation and chemotherapy are the available treatment options for bone tumors, however, the gold standard treatment is leg amputation. The goal of these treatments is to control pain due to the micro-fracture induced by the cancer and to limit its spread. The cure for bone cancer, unfortunately cannot be achieved for osteosarcoma in dogs and the life expectancy can only be prolonged by use the combination of surgery and chemotherapy. Contrary to dogs, bone osteosarcoma is curative with surgery alone in cats and no chemotherapy is needed

WHAT IS LIMB OR LEG SPARING SURGERY?

Limb sparing procedure is used for selective cases to salvage the leg in conditions in which leg amputation is not an option. This procedure is performed by removing only the bone tumor and preserving the entire leg. The portion of the bone that has been removed is replaced with a fake segment of bone. The complication rate for leg salvage technique is high compared to limb amputation due to an increased risk of infection.

WHAT IS THE OUTCOME AND PROGNOSIS WITH BONE CANCER

The prognosis for dog with leg osteosarcoma is poor, and the survival time is 6 months for 50 % of the patients and only 10 % of dogs are alive at 12 months after surgery. Chemotherapy combined with surgery will provide an increase in survival time. Factors that play a role in the prognosis with leg osteosarcoma are the presence of tumor metastasis (spread), the tumor size and location on the bone.

In contrast to dogs, cats with bone tumors have a better prognosis and with complete removal of the tumor, a cure can be achieved.