Bone Cancer in Dogs

While any diagnosis of "cancer" is bad, bone cancer in dogs is especially bad. It is aggressive, progresses rapidly, and it is difficult to control their pain.

What Is Bone Cancer in Dogs?

Cancer, in general, is a collection of cells that are behaving abnormally. They are dividing and replicating too quickly, and they can be longer lived than normal.

Bone cancer, or osteosarcoma, then is made of bone origin cells that are mis-behaving. This particular cancer likes to pack its bags and move around the body - this is called metastasizing. So while it will start in a bone, it can end up in many other places. Osteosarcoma most commonly travels to the lungs.

What Does Bone Cancer in Dogs Look Like?

The first thing an owner will usually see is a lameness - the dog is limping. This is because most (82%) of the time bone cancer in dogs will begin in the larger leg bones. (Interestingly, Boxers are more prone to developing this cancer in the flat bones of their skull).

Sometimes the lameness starts slowly and worsens over a few weeks. Sometimes the lameness appears very suddenly. Everydog will have different pain tolerance abilities, and owners have varying success with noticing changes in their dogs, and some tumors will grow faster than others; hence the differences in how osteosarcoma in dogs looks at the beginning.

Any dog that has a severe lameness, or a mild lameness that lasts for more than a day or so, should visit their vet!

Your veterinarian will try to determine where the pain is coming from. Once this is done, most often x-rays are recommended to look more closely at the area. I know this can be a little expensive, but if you really want to know what's going on, then you need to go ahead and do the x-rays!

So lets look at a few x-rays. This first set is showing canine osteosarcoma in a front leg. The opposite leg is there so that you can see what normal looks like. You can see how the bone cancer destroys the normal texture and shape of the bone.

Bone Cancer in Dogs
Comparison X-ray Bone Cancer in Dogs


X-ray Normal Dog Knee

Bone cancer in dogs can also be in a back leg. This is a normal dog knee. In each of these x-rays, the femur, or thigh bone, is to the top of the picture. The tibia, or shin bone, is the bone on the bottom part of the picture.

Canine Osteosarcoma X-ray
X-ray Osteosarcoma in Dog Knee


X-ray Fracture from Bone Cancer in Dogs

Do you remember up above, when I said that bone cancer destroys the normal texture of the bone? This dramatically weakens the bone. This x-ray shows what is called a pathologic fracture of the femur, because the bone has cancer in it, down by the dogs knee.

What Dogs Are at Risk of Getting Osteosarcoma?

Bone cancer in dogs is more common in large and giant breed dogs who are middle aged or older. Breeds that seem to be more prone to osteosarcoma include Rottweilers, Greyhounds, Scottish Deerhounds, Great Danes, German Shepherds, Saint Bernards, Golden Retrievers, Irish Setters and Boxers.

Smaller dogs can get bone cancer, it's just not as common as in the large breeds. And, like Boxers, the little guys will more often get it in their skulls, or in their spines.

What Can Be Done About It?

Well, I'll be honest here - canine osteosarcoma is a pretty bad diagnosis. The cancer is aggressive. Most often it has already spread by the time of diagnosis. It is also a very painful disease.

Usually the series of events goes something like this:

1. Owner notices a lameness, watches it for a while hoping it will go away.

2. Owner brings dog in to their veterinarian.

3. Veterinarian localizes the pain, does x-rays to look at the area more closely. A probable diagnosis is made.

4. Treatment options and the prognosis are discussed with the owner. If the owner chooses to pursue treatment, then chest x-rays (at a minimum) and sometimes a bone biopsy are done to assess the stage of the disease.

5. Treatment appropriate for the dog and within the owners wishes is pursued.

Treatment Options

This is a disease that has treatments, but not a cure. Your goal is to provide a good quality of life, for the time that they have left.

1). Amputation of the affected limb, followed up with full course chemotherapy, is the most aggressive treatment course available.

Amputation is only an appropriate option if the dog will be able to be mobile without that limb. For those dogs that have severe arthritis in the limb opposite the cancerous limb, an amputation is unlikely to improve their quality of life. Because the other "good" limb is painful and poorly functional, removal of the cancerous limb can leave them unable to rise and walk on their own.

Also, if chest x-rays show cancer within the lungs at the time of diagnosis, then amputation is generally not done,as the dogs' likely survival time would be much shorter. It makes no sense to spend your last days healing from a surgery that wasn't able to extend your life...

Sometimes it is possible to do a "limb sparing" surgery. In this case the cancerous bone, or a part of it, is removed but the remainder of the leg remains. You need a very good surgeon for this procedure, and if it is even an option will depend on where and how big the tumor is, and if there is evidence of metastasis yet.

Pros This Option

*The painful limb is removed - best pain control

*Best chance longer survival (1-2 years)

*Dog has a very good quality of life

Cons This Option

*High expense

*Big time/energy commitment from owner

*Limitations on patient selection

Amputation without any follow up chemotherapy has an average survival time of only 4-6 months. If you plan to go for it, then do it all!

2). Radiation Treatment with IV aminobisphosphonates and oral pain control will generally result in moderate to good pain control, with a life expectancy of 4-12 months.

Pros This Option

*Less expensive

*Pretty good pain control

*More individualization of treatment possible

Cons This Option

*Not as long of survival time

*Still moderately expensive

*Possibility of bone fracture remains

3). Oral Pain Medications alone. With no direct treatment of the cancer itself, the dogs' life expectancy is quite short - around 2 months.

Pros This Option

*Most affordable

*Treatment least time intensive

*Dog has a fair quality of life

Cons This Option

*Least pain control

*Fracture of limb is likely

*Least time with pet

Bone cancer in dogs is an unfortunate diagnosis. Do what you can, and what is best for the both of you....

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