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April 26, 2018

Osteosarcoma

I’ve seen my fair share of osteosarcoma at work, it’s a terrible disease. With over 10 years in the breed part of me feels fortunate to have gone so long before seeing it in my own pets. But with every limp it springs to the back of my mind, that sickening feeling deep in the pit of my stomach, and this time was no different.

She started limping after a fence-fighting spat, but when the limp didn’t go away with a short course of pain meds, I brought her in for radiographs. Since we do not live in a location with fungal diseases the diagnosis was straightforward. I was heartbroken.
The signs of bone cancer can be as obvious as a limp or swelling in the bone but in some cases the dog can simply seem tired or just not eat.

Giant dogs are more likely to develop the cancer and osteosarcoma accounts for 85% of tumors in the bone. it is most commonly seen near the wrist (distal radius and ulna) but can also be seen commonly near the knee or shoulder. It is a primarily a cancer of the long bones, so if the issue appears to be in the joint itself or appears to affect multiple bones it is likely a different condition.


The metastasis rate (rate at which it spreads) is high with Osteosarcoma. Typically by the time it’s diagnosed almost 90-95% of dogs already have tumor cells in the lungs. This type of cancer is also considered very painful, many people with Osteosarcoma rate it as painful as a broken bone.

The practical options for treatment of osteosarcoma are pretty limited. The prognosis for osteosarcoma is really poor with most individuals not lasting more then 6 months. Amputation and chemotherapy can extend the prognosis but both can better address quality of live . Palliative care is probably the most common as cure is rarely if never sought in companion animals. There are a wide assortment of pain medications that can be used; opioids, NSADIS, cannabinoids and radiation therapy are common options and a combination of medications are typically necessary to maintain comfort.

Amputation and limb spare surgery are also options for longer term palliative care. Both surgery options immediately remove the painful portion of bone but both have significant downsides in the giant breed. With amputation the stress of surgery and recovery and the large weight of a giant spread on just three limbs can be a real downside. Limb spare surgery is where the healthy portions of the bone are salvaged and hardware is used to maintain the weight bearing portion of the effected limb. This can be a costly option and finding a willing and capable surgeon can be difficult. It still has the same surgery and recovery downsides as simple amputation, which for the Neapolitan Mastiff can be very real and debilitating in themselves.

Limb Spare Surgery for Osteosarcoma is a relatively new surgical procedure pioneered by Bernard Séguin, DVM MS DACVS American College of Veterinary Surgeons. With the procedure the painful portion of bone is removed and the weight bearing is transferred onto the implanted hardware. unfortunately the complication rate is high with infection, tumor recurrence and implant problems being the most common complications.

Vocabulary
Cannabinoids = CBD oil from the cannabis plant
Metastasis = when cancer cells spread, typically spread to the lungs
Palliative care = comfort care