Osteosarcoma is a common bone
cancer in large and giant
breed dogs. It is uncommon in smaller dogs (and rare in cats).
It usually affects the long bones of the legs, especially the
front legs. Osteosarcoma is mostly, though not exclusively, a
disease of older animals. It can
be treated, but the disease is quite serious.
No genetic link has been confirmed, although
Rottweilers do get osteosarcoma more often than any other
breed. There is no known cause, and therefore no way to prevent
the disease. Because osteosarcoma metastasizes, or spreads,
quickly, it is very difficult to cure. Treatment usually
focuses on keeping the dog comfortable for as long as
How Is Osteosarcoma in Dogs Diagnosed?
The most common symptom of osteosarcoma is lameness, which
might be intermittent. If you handle the affected leg, you
might notice a sensitive area or a lump, but this is not always
the case. The lameness can come on suddenly after vigorous
exercise, or it can come on slowly. Generally, if a large dog
starts limping for no apparent reason, you should call your vet.
At the vet’s office, an x-ray will be taken -- osteosarcoma
often shows up as a Swiss cheese-like appearance in the bone. A
needle biopsy confirms the diagnosis, though this can cause the
dog more pain. Blood and urine samples will help your vet
understand your dog’s overall health so you can make treatment
decisions that are right for your dog. Your vet will probably
also want to do a chest x-ray in order to check for metastases
in the lungs, although x-rays cannot detect the smallest
tumors. Because osteosarcoma spreads so easily, vets assume
that metastases are present whether they can see them or not.
How Is Osteosarcoma Treated?
There are a couple of different options for treating
osteosarcoma, depending on your dog’s overall health. The
standard treatment is amputation of the affected leg in order
to remove the primary tumor,
followed by systemic chemotherapy in order to attack any
secondary tumors. Sometimes it is possible to remove the tumor
without amputating the leg, but the loss of a leg does not
seriously disable most dogs. Occasionally, this combination of
surgery and chemotherapy results
in a complete cure. More often, it simply buys time and makes
the patient more comfortable.
Some dogs are not candidates for surgery because they have
severe arthritis in the other
limbs or other medical problems. Some people elect not to do
chemotherapy because of the expense or for other reasons.
Surgery without chemotherapy cannot cure osteosarcoma, but it
does lessen the dog’s pain. Chemotherapy without surgery does
not do much good. For dogs who cannot have surgery, radiation
treatment can slow the disease and relieve pain. Any dog with an
osteosarcoma diagnosis should also receive pain medication.
What Is the Outlook for My Dog?
Osteosarcoma is a serious disease. A cure is possible, but
unlikely. What you can do is make the months or years your dog
has left as good as possible. Bone cancer is a very painful
disease, so treatment is about relieving pain, even more than
it is about extending life. Amputation might seem like a
drastic step, but most dogs adapt to the loss of a leg very
well, and removing the primary tumor means the relief of
Half of all dogs treated for osteosarcoma with surgery and
chemotherapy live at least one more year. A quarter live at
least two more years. Two years is a short time for us, but it
is a long time for a dog. If those extra months or years are
good, happy years, you have fought for your friend and you have
Osteosarcoma In Dogs And Cats
Osteosarcoma, or OSA, is the most common bone tumor found in dogs. This type
of cancer can also occur in cats, but it is far less common. In dogs,
osteosarcoma is very aggressive and tends to spread rapidly to
other parts of the body, making early detection and treatment
incredibly important. Here we’ll review causes and symptoms so
that you’ll know what to look out for, as well as treatment
options so you’ll know what to expect.
Causes of Osteosarcoma in Dogs and Cats
The causes of osteosarcoma in dogs and cats are not well
understood. What we do know is that middle-aged
to older large and giant breed dogs are the most
Osteosarcoma can occur in any bone in the body, though in dogs,
most tumors appear in the front limbs near the “wrist.”
Symptoms of Osteosarcoma in Dogs and Cats
The symptoms of bone cancer can be subtle, and may include
lameness, swelling or a lump near the tumor site, bone or joint
pain, lethargy, and loss of
Lameness is certainly the most common symptom and often the
most obvious as well. A dog may experience sudden lameness (for
example, following strenuous exercise or jumping off the bed)
or the lameness may develop more slowly.
Diagnosing Osteosarcoma in Dogs and Cats
Many pets end up at the vet’s office after their owner notices
lameness that is not resolving. The symptom is investigated
with a radiograph, which will reveal a problem area if
osteosarcoma is present. In order to reach a definitive
diagnosis, the problem area must be biopsied. However, not all
veterinarians perform this procedure; in some cases, the
results of the radiograph will be suggestive enough to assume a
In addition, chest x-rays, blood testing, and a urinalysis will
be performed to assess the pet’s overall health. In most dogs
(around 90 to 95%), the tumor will have already metastasized
(spread) at the time of diagnosis. Osteosarcoma tumors most
commonly spread to the lungs, but this rarely shows up during
testing as the metastatic tumors are initially microscopic.
However because of the high incidence of metastasis, most pets
are treated for it regardless of what testing reveals.
Treatment for Osteosarcoma in Dogs and Cats
Because osteosarcoma tumors are very likely to spread, the most
common treatment is amputation of the affected limb followed by
chemotherapy to treat existing metastasis or metastasis that
can’t yet be seen. For many owners, amputation is a difficult
decision, and not all pets are candidates (for example, dogs
with severe arthritis in the affected limb).
However amputation is a good option for many other dogs, and
dogs with three legs can actually function very well.
If the dog is not a candidate for amputation, or if the owner
decides that they do not want to go through with it, the only
other option is palliative care. Palliative care aims only to
make the animal more comfortable; it does not solve the
underlying problem. Common palliative treatments include
radiation therapy and drugs (analgesics) to reduce pain. Pets
treated with palliative care tend to survive only 6 months
before they succumb to the cancer or require euthanasia.
The prognosis for pets with osteosarcoma depends on the
severity and spread of the disease as well as the treatment
carried out. Pets who undergo amputation and chemotherapy tend
to have a fair-to-good prognosis, and some pets are even
completely cured. As mentioned above, pets that receive only
palliative care survive an average of 6 months. Your
veterinarian will help you determine the best course of
treatment for your pet.
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