The most common bone tumor in pets, Osteosarcoma, usually affects older or giant breed dogs but has been seen in younger canines as well. It is rare in cats. Although it is an aggressive cancer that can be found in any bone, it mostly develops in the limbs. Therefore, Osteosarcoma steadily becomes more painful as it progresses.
Patients with Osteosarcoma in the limbs will show swelling at the developed site along with increased lameness. Sometimes, the first sign that the patient has bone cancer is a fracture at the site of the tumor. Other signs would depend upon the location of the cancer: e.g. bone cancer of the spine could present neurological symptoms. Due to the high rate of metastasis (spread of tumor cells) to the lungs, x-rays are taken of both the chest and the affected limb. Sometimes bone scans are done of the other limbs as well.
The spread of cancer to the lungs and other organs is the most common cause of death in patients with Osteosarcoma. As other tumors can show up in the limbs as well, a biopsy of the affected site may be the only way to confirm the presence of bone cancer.
As Osteosarcoma is a painful, aggressive cancer with a high rate of metastasis, a positive diagnosis of Osteosarcoma usually means the affected limb must be removed followed by chemotherapy and possible radiation. The more commonly used chemotherapy drugs include Carboplatin, Cisplatin and, sometimes Doxorubicin. There are side effects that are associated with chemotherapy drugs but the risk usually is outweighed by the benefits. A veterinary oncologist would be the best source of information regarding chemotherapy drugs.
Pets with cancer can experience weight loss due to the presence of the cancer. Post-surgical pain, lack of appetite, and the side effects of the chemotherapy drugs such as vomiting and nausea may also occur. It is important to provide nutritional support to decrease post surgical complications, improve quality of life and increase response to therapy. A special diet can be suggested by the veterinarian, the veterinary oncologist or a veterinary assistant.
The prognosis depends on the location of the tumor, how extensive the disease is, the general health of the pet, and if the cancer has spread to other organs. If the cancer has spread to other organs or limbs, the prognosis could be poor. A patient with an amputated leg does not lessen the quality of life for your pet but it does depend upon each individual animal. There is a website called Tripawds.com that is a wonderful source and help center for people with pets who have gone through an amputation to share their stories. Although Osteosarcoma is not preventable, effective treatments and early diagnosis can improve the life of your pet.