Pet Care Resources Primary Bone Tumors in Dogs and Cats

Medical Oncology

Primary Bone Tumors in Dogs and Cats

Primary Bone Tumors in Dogs and Cats

Bone tumors are among the most common tumors in dogs but are rare in cats. Most arise spontaneously without a known cause. When they occur, bone tumors are typically aggressive in dogs but may be less so in cats depending on the specific tumor type. Bone tumors may affect the long bones of the limbs or the bones of the spine, pelvis, ribs, and/or skull.

The most common bone tumor in dogs and cats is osteosarcoma. Other primary bone tumors include chondrosarcoma, hemangiosarcoma, and fibrosarcoma.

Large to giant breed dogs are more commonly affected but small dogs may develop bone tumors as well. Although older dogs and cats are most commonly affected with bone tumors, younger dogs are also at risk of developing primary bone tumors.

Diagnosing Bone Tumors

The most common sign for a dog or cat with a bone tumor is lameness (limping) that isn’t improving with rest or supportive medication. You may also notice a firm swelling over a bone or joint. X-rays of the affected area can be helpful to rule out other issues such as fractures or soft tissue injuries. In addition, primary bone tumors typically have a characteristic appearance on X-rays. Additional testing to confirm the diagnosis may include a fine needle aspirate (FNA) or biopsy.

If a primary bone tumor is suspected, your veterinarian may recommend tests to determine if the cancer has spread. These tests are known as staging tests. Primary bone tumors most commonly spread to the lungs, so the care team may encourage X-rays of the lungs prior to pursuing further therapy. Lab work is also recommended to assess overall health. There are potential markers in the blood work regarding how aggressive the tumor may be. Additional tests may be recommended based on these results. These include a CT and/or an ultrasound of the belly.

Treating Bone Tumors

The primary treatment for primary bone tumors is surgery. Surgery may entail amputation of the affected limb, removal of the affected rib, or removal of a portion of the jaw. In some cases, surgical implants such as limb sparing can be considered but this will be discussed based on the specific tumor type, location, and extent of the tumor.

Radiation therapy may also be considered as a primary treatment option (stereotactic radiation) or to provide palliative/comfort care. Radiation therapy can help alleviate pain from a primary bone tumor.

Chemotherapy is often used for osteosarcoma following surgery or stereotactic radiation and may be used in the treatment of other primary bone tumors.

Prognosis for Pets

The prognosis for dogs or cats with primary bone tumors depends on the specific tumor type, stage of the cancer, and treatment. Your MedVet oncology team will work with you and your family veterinarian to provide the best care for your pet.

Meet Some Cancer Fighters

Dog fighting bone cancer

Lola Crane is a 10 1/2-year-old Lab who was diagnosed with osteosarcoma.  She underwent amputation of her right rear leg followed by chemotherapy. Recent thoracic radiographs show that she is still free of metastatic disease and she is living her best life!

Cat fighting bone cancer

Brandy Belle was diagnosed with osteosarcoma nearly two years ago. She underwent amputation of her hind leg which has never slowed her down. Following surgery, she completed a chemotherapy protocol. She remains in remission, having kicked cancer to the curb.

By Bobbi McQuown, DVM, DACVIM (Oncology) , Mia Livaccari, DVM, MS, DACVIM (Oncology) |
October 28, 2022