All Pets Veterinary Clinic

Bone Cancer

This is an older Rottweiler that presented for pain, lameness, and swelling in the front
leg. After examination and x-rays of the area it was suspected that the dog had a bone
tumor. However, other diseases such as infection due to fungus, cartilage cancers, etc.
can have a similar history and apperance. To obtain a proper diagnosis so that the
correct treatment can be recommended, a biopsy of the affected bone is indicated.

Afer exposing the affected area of bone, a trephine punch is used to obtain biopsy samples
from the center of the bone. Once the bone is exposed, the punch is screwed through the
cortex or outer surface of the bone and placed into the medullary cavity.

This is what the bone looks like at the site of biopsy. The bone was soft and brittle.

The long plunger (lower right) is used to release the biopsy samples from the biopsy punch. The
samples were submitted for histopathology and diagnosed as osteosarcoma. Osteosarcoma
is the most common bone tumor of dogs. Osteosarcoma has a high rate of spread to the lungs
and other tissues. At the time of diagnosis, most osteosarcomas have already spread to the
lungs. The early cancer cells are often not detectable on x-rays until they have grown
to a significant size. Because of the high rate of spread, the treatment of choice for
osteosarcoma is limb amputation and follow up chemotherapy. Withouth limb amputation,
many dogs will experience spontaneous fractures at the site of the tumor, chronic pain
and discomfort, and a continuing chance for spread of cancer cells.

Many pet owners will not consider chemotherapy as a treatment option because of
the fear of side effects. While there are side effects and they can be serious,
animals will often tolerate chemotherapy better than humans. The chemotherapy
protocol often recommended for osteosarcoma involves the administration of cisplatin
IV every three weeks for at least 5 doses. The first dose is given at the time
of limb amputation. Without chemotherapy, dogs often have a survival rate of under
6 months. With chemotherapy, survival time can be extended to a year or more.
Of course, there is always individual variation and overall survival times depend
on many factors such as age of the animal, length of time the tumor was present
before diagnosis, etc. Given the age of this particular dog, the duration of
the disease, and several other factors the owners elected euthanasia when the
the diagnosis was confirmed.

Karen Blakeley, DVM, MPH
26 July 2004