Canine bone cancer signs

Q: Victor, our 8-year-old great Dane, is limping on his right front leg, and there’s a hard swelling low on that leg. His veterinarian examined him and x-rayed his leg, and then told us she was certain he had osteosarcoma, a bone cancer.

She recommends amputation and referral to an oncologist. How can the vet be so sure without a biopsy? We’re caught between feeling devastated and hoping she’s wrong.

A: I’m sorry to hear of Victor’s probable bone (osteo-) cancer (-sarcoma). Osteosarcoma is by far the most common bone tumor in dogs, striking more than 10,000 American dogs every year.

It targets large-and giant-breed dogs when they are 18-24 months old or, more often, 7-9 years of age. It usually affects the legs, and in specific locations. On the front leg, it’s seen in the upper part of the humerus or, as in Victor’s case, the lower part of the radius, just above the wrist.

Osteosarcoma presents a distinctive appearance on radiographs (x-rays), so the radiographic findings combined with Victor’s breed, age and physical exam results make your vet’s diagnosis quite certain. On radiographs, osteosarcoma can resemble a fungal infection of the bone, but this disease occurs only in certain geographic regions of the country. A biopsy can confirm the diagnosis.

Treatment involving amputation to help control pain, plus chemotherapy and/or radiation therapy to delay the cancer’s spread to other parts of the body, can prolong survival to around a year. A second opinion from a board-certified veterinary oncologist is advisable, as your veterinarian suggests.

My best wishes are with you all.

Editor’s Note: In the US, cancer is the leading disease-related cause of death for dogs. Here we discuss common cancers in dogs and their signs.

Lee Pickett, V.M.D. practices companion animal medicine. Contact her at askdrlee@insurefigo.com.