‘Mack’ is a 4 year old Newfoundland with a sweet, goofy disposition and a whole LOT of hair. He tops the scales at over 160 pounds, but wouldn’t harm a fly. He came to my vet hospital recently for evaluation of a progressive lameness over several weeks. By the time he came into the clinic he wasn’t bearing any weight on his left hind leg. When I examined him, I could see is lower shin bone was swollen, hot and very painful. Concerned, I convinced the owners to let me do some diagnostic testing of the affected area. This confirmed my fears. Mack had bone cancer.
It is estimated that up to 50% of dogs and 30 to 35% of cats will be affected with some type of cancer in their lifetimes. This is one of the reasons pet insurance agency, Pets Best Insurance has just launched a new "Cancer Only" pet insurance policy-- which may significantly help make cancer treatment more affordable for pet owners. Purebred dogs can be at an increased risk, and there are certain breeds that tend to be over-represented, such as Golden Retrievers and Boxers. It is postulated that the documented increase in cancer cases in our companion pets is likely related to the fact that pets are living longer. Many people are keeping their pets in their homes and feeding high quality diets, which is translating to longer life spans.
I spoke with Mack’s owners about osteosarcoma (OSA), the type of bone cancer that he had. OSA is the most common type of bone cancer seen in dogs, accounting for greater than 80% of bone cancer cases. Large and Giant breed dogs, such as Mastiffs, Rottweilers and Golden Retrievers are far more likely to develop this type of cancer than their smaller breed counterparts. The average age at diagnosis is about 7 years, but can happen in very young and very old dogs as well.
Osteosarcoma is a bone cancer that typically affects the long bones in the body, such as the femur or tibia. It tends to grow at the ends of these bones, not in the middle. Most patients present for evaluation of chronic progressive lameness, heat and swelling at the site.
Mack’s owners were devastated by the diagnosis. Coming to terms with cancer in such a young dog was compounded by the fact that this is an aggressive cancer with a poor prognosis for long term survival. The treatment of choice is generally amputation of the affected limb, followed by chemotherapy. This aggressive form of treatment gives an average of 10 to 12 months of survival time. Without surgical treatment, with pain management alone, most dogs die within 2 to 3 months, sometimes sooner.
Cancer diagnosis in veterinary medicine often comes with a stigma. People’s understanding of cancer treatment and chemotherapy comes from exposure to human cancers, which is very different. Understanding how treatment for veterinary cancer differs from human cancer treatment is crucial. Pets tolerate chemotherapy much better than people in general. They don’t typically lose their hair, or suffer severe nausea. They don’t have to spend excessive amounts of time in the hospital and can generally be treated on an outpatient basis.
Mack’s owners listened to all the statistics about treatment for OSA, and decided to go home to think about their options. Amputation and chemotherapy would be costly. They didn’t have a pet health insurance policy for Mack, which, in my opinion, would have been an invaluable asset in this case. Despite this, they decided to go forward with aggressive treatment.
We discussed our concern that Mack, at 160 pounds, is not the most graceful and agile animal. We weren’t sure how he would do as a ‘tripod.’ His owners were convinced they would like to give it a try and he was scheduled for surgery later in the week. His surgery went very well and he seemed relatively pain free. He was very confused about the loss of his hind leg and struggled with walking due to the added heavy pain medications causing in-coordination.
Over the next several days he became more and more strong. After his incision was healed, he presented for chemotherapy. Mack would undergo 6 rounds of intravenous chemotherapy. The chemotherapy drugs target rapidly growing cells and kill them. Since neoplasia tends to be rapidly growing, these cells are preferentially killed, although occasionally healthy bone marrow can be affected as well. Mack gets regular blood work to ensure this hasn’t happened.
Throughout the entire process Mack has shown incredible optimism and good nature. His owners know they probably won’t have him much longer due to his disease, but to them, the extra year is worth the veterinary visits and surgery. Cancer can be such a devastating diagnosis to swallow with a beloved pet. Many types of cancer are quite treatable with the recent advancements in veterinary oncology. Having dog or cat insurance is an important consideration for any pet, especially the cancer-prone breeds, to help pet owners take advantage of these new technologies, and focus on healing.
1Thamm VMD, DACVIM, D. Dispelling the Myths of Veterinary Oncology. British Small Animal Veterinary Congress 2011
2Shell DVM, DACVIM, L. Osteosarcoma. http://www.vin.com/Members/Associate/Associate.plx?DiseaseId=1975
7/2/2007.
3Heeb DVM, DACVIM, H. Common Canine Neoplasms (V211). Western Veterinary Conference 2008