A few years ago, an older husky/shepherd dog named, Victory, came in for licking intensely at his back leg. He had what is commonly called a “hot spot”. This is an area of inflammation and infection in the skin. It can be triggered by many things, from fleas to allergies. This area was a bit unusual in that it was over his tibia (shin bone). It was treated with a topical lotion and oral antibiotics and was resolved.
About six weeks later he came back, again with the same problem, but this time he was limping on that leg and the bone itself was painful. I recommended to the owner that we take a radiograph (X-ray) to understand what the bone was doing. The radiograph revealed a large tumor growing in the middle of the bone pushing it outward. It had nearly eaten away 50% of the tibia.
Bone cancer, unfortunately, occurs in dogs and cats. There are a few different types of bone cancer, but osteosarcoma is the most common and aggressive type. I have seen it in animals as young as 6 months old, but more commonly it’s found in older pets. On x-rays, it looks very different from infections or other conditions that could affect the bone.
In hindsight, the hot spot from earlier was his reaction to the growing discomfort in his bone. This was a sign letting us know that his leg hurt. Even before the distortion of the bone, Victory knew something was wrong with his leg.
I went back to the owner to discuss my findings. I recommended that we take radiographs of the chest to look to see if the cancer had spread (metastasized). The owner agreed, and luckily the new rads (X-rays) showed no obvious spread at that time.
Although new research is always being done, the options for treating bone cancer is limited. Survival time is best with surgery followed by chemotherapy. Chemotherapy is used because the cancer often spreads microscopically at the time of diagnosis.
Other non-invasive ways exist, including radiation and drugs. Radiation can help to slow down the tumor if surgery is not an option. There is a combination of pain medications and anti-inflammatory agents that can also help slow it down.
One has to take into account all the circumstances and options for both the pet and the family. Bone cancer is extremely painful, and doing something to address the animal’s needs is the most important. Even with surgery and chemotherapy, survival time is only about 9-12 months on average, as surgery usually requires amputating the entire limb.
There are some limb sparing procedures, and even some work with prosthetic limbs now, but the majority of patients will be moving on three legs after surgery. They actually do extremely well most of the time. However, it is always important to assess the other three limbs to determine if they can support the patient. If there is a lot of arthritis, or other conditions in the remaining legs, the pet may not do as well.
The owners consented to amputating the back leg and would consider chemotherapy. After checking blood work for any other problems (none), I amputated his hind leg above the knee a few days later. He did well through anesthesia and recovery, and was on a constant infusion of morphine and other pain medications for 24 hours.
He went home a few days later, and was walking on his own in 24 hours. I had the lab analyze the bone to determine what type of tumor it was. He had the worst case, an osteosarcoma. I notified the owners, and they were going to meet with our oncologist the same day I took out the sutures.
The owners decided that at 11 years old, they did not want to pursue chemotherapy for him. His survival time, at best, was considered to be 6 months. Eleven is old already for a big dog, and at least his pain from the tumor was gone.
A few days later, I called the owners to check in on him. He was getting around really well, and they were very happy that he was comfortable. I talked with them again about chemotherapy, but I understood it wasn’t an option for them.
They did ask me if there was anything else to do. I focused on making sure he was happy, and keeping him comfortable. I prescribed a pain medication for him to take on an as needed basis, and then researched an antibiotic that had been shown to have potential anti-angiogenic effects for some types of cancer.
Anti-angiogenic explained: Tumors, like all cells, need the oxygen in blood to grow; slowing access to this source slows the rate of tumor growth. This could perhaps keep Victory alive and comfortable longer. I discussed this with them as an option, it had little chance for side effects, and was cheap. He was started on a once a day dose of this medication.
A few months later, I saw him for a follow-up. I barely recognized him. He was happy, tail wagging and MOBILE! He had lost some weight, and when I asked the owners about it, they said he had been constantly chasing the other dog around outside.
They did not want to take new chest x-rays to see if anything had changed, and I was fine with that. We kept him on his medications, and I told them to keep in touch with me if anything changed. I was glad that he was doing well, but I was concerned for how long.
That was 28 months ago, as of March 2012. I saw him just before Christmas 2011 and he had slowed down some, but was alive to celebrate his 13th birthday. I hope that he continues to do well. He takes his antibiotic every day, along with his pain medications as needed.
His case is definitely not the norm. Most patients, even with aggressive treatment, do not get past 12 months with osteosarcoma. I tell this to remind you that rules are meant to be broken, and to do what you feel is best for your family.
With cancer in veterinary medicine, it is the caregivers and the medical staff that know the big words like metastatic osteosarcoma. We study these diseases and learn the standard diagnoses, treatments, recovery and survival times. I’m just glad that Victory didn’t read the book.
*August 15, 2012 update – I recently heard from Victory’s parents and can happily let everyone know that he is continuing to do well 3 years after surgery. Here is a recent photo.