Osteosarcoma (bone cancer)
Bladder, Brain, Head & Neck, Hemangiosarcoma, Lymphoma, Mammary, Mast Cell Tumor, Osteosarcoma, Skin, Testicular Cancers
Antiangiogenesis, Chemotherapy, Clinical Trials, Radiation, Surgery, Complementary & Alternative Treatments
Diagnosis of canine osteosarcoma is initiated with complete orthopedic and neurologic
examination (to rule out other causes of lameness), physical examination, and regional
radiographs (x-rays).  Some oncologists have suggested that biopsy is not needed if the
radiographs show an obvious bone tumor, however, if there is any question about the lesion on
the radiographs, a bone biopsy should provide clear results.

To obtain a definitive diagnosis, it is necessary to aspirate the tumor with an ultrasound-guided
needle or perform a bone biopsy (removal of a tiny section of the bone) in order to attempt to
identify the type of tumor. These procedures require sedation or anesthesia as they would
otherwise be painful. There is often a large amount of bony reaction associated with this type of
tumor, so it can be difficult to obtain an adequate sample of the actual tumor cells. Additionally,
small samples are taken in order to minimize the spread of the tumor cells along the biopsy
pathway and to avoid fracturing the bone. For these reasons, the biopsy procedure does not
always yield a diagnostic sample. Even though only very small samples are taken, and bone
biopsies are performed with the utmost care, this procedure always carries a small risk of
fracturing the bone.

If osteosarcoma is diagnosed, radiographs (x-rays) of the dog’s chest are taken to see if the
tumor has spread to the lungs. It is important to find out whether the cancer has spread
(metastasized) to the lungs, as treatment options and prognosis are very different if lung
metastasis has occurred.  Up to 90% of these tumors will have metastasis to the lungs at the time
of diagnosis, but because of the small initial size of the metastases, less than 10% will initially
show up on a chest x-ray.  Because of this high incidence of metastasis, all dogs with
osteosarcomas are treated as if they have metastasis to the lungs regardless of the findings on
the initial lung x-rays.  In the initial diagnostic stages, aspirate (sampling of cells) of lymph nodes
and any skin masses and an abdominal ultrasound are generally done. Again, these steps are
necessary in order to assess the spread of the cancer and health of the dog.

Another diagnostic test that may be performed is a bone scan. This test, which requires an
overnight stay in the hospital, will help determine whether the tumor has spread to other bones
and how much of the bone where the primary tumor is located is affected.

The location and radiographic appearance of the osteosarcoma in the limb are quite classic but
there are a few other possible conditions that cause lytic lesions in bone: the chondrosarcoma,
or the squamous cell carcinoma, or the synovial cell sarcoma.  For these reasons, many
veterinary oncologists will recommend a bone biopsy to confirm the diagnosis.

Chondrosarcoma is a cartilage tumor, possibly not as malignant as the osteosarcoma. The
chondrosarcoma generally occurs on flat bones such ribs or skull bones and is not usually found
in the limbs. Still, should a chondrosarcoma occur in the limb, treatment recommendations would
still include amputation of the affected bone and biopsy of the tissue after amputation would allow
for any adjustments in chemotherapy.

Squamous cell carcinoma is a tumor of the external coating of the bone (called the
“periosteum”).  This is a very destructive tumor locally but it tends to spread relatively slowly.
Again, a bone suspected of  malignant tumor should be amputated and the tissue then analyzed
and treatment adjustments made thereafter. The squamous cell carcinoma tends not to arise in
the same bone areas as the osteosarcoma; it tends to arise in the jaw bones or in the toe bones.

Synovial cell sarcoma is a tumor of the joint capsule lining. It’s hallmark is that it affects both
bones of the joint. The osteosarcoma, no matter how large or destructive it becomes, will never
cross over to an adjacent bone.

Fungal bone infection: Coccidiodes immitis is a fungus native to the Lower Sonoran Life Zone of
the South West U.S.  It is the infectious agent of the disease called “San Joaquin Valley Fever” or
just plain “Valley Fever.” (More scientifically, the condition is called “coccidiodomycosis.”)  In most
cases, infection is limited to a few calcified lymph nodes in the chest and possibly lung disease. In
some rare cases, though, the fungus disseminated through the body and can cause a very
proliferative bone infection. The bone infection of coccidiodomycosis is proliferative and lacks the
lytic lesions that are so typical of the osteosarcoma.
Risk Factors
The specific cause of osteosarcoma is not known.  However, because osteosarcoma tumors are
frequently found near growth plates, it is speculated that factors that affect growth rates, such as
diets that promote rapid growth in puppies, appear to influence risk.  

Osteosarcomas tend to anchor themselves in areas of increased bone remolding, said Dr. Kim
Cronin, oncologist at the University of Pennsylvania. "Every time you have cell damage or
increased turnover, the DNA is more likely to make a mistake when coding for new cells, which can
lead to tumor formation."  So naturally, previous fractures and chronic bone infections are
predisposing factors.  These tumors are most likely to occur in the limbs, particularly the forelimbs,
which bear most of the body weight; other bones, such as the ribs and skull can also be affected."

Ionizing radiation, chemical carcinogens, and foreign bodies (including metal implants, such as
internal fixators, bullets, and bone transplants contribute to the development of osteosarcoma. In
addition, there have been correlations with genetic predisposition to tumor development in certain
family lines. Dogs with osteosarcoma have been found to have aberrations of the p53 tumor
suppressor gene. In laboratory animals, both DNA viruses (polyomavirus and SV-40 virus) and RNA
viruses (type C retroviruses) have been found to induce osteosarcoma.

Research was performed in 2002 to determine if spaying or neutering a dog increased the risk of
developing bone cancer.  Experimental and clinical evidence suggests that endogenous sex
hormones influence bone sarcoma genesis but  the hypothesis had not been adequately tested in
an appropriate animal model.  A historical study  was conducted of Rottweiler dogs because they
frequently undergo elective gonadectomy and spontaneously develop appendicular bone
sarcomas, which mimic the biological behavior of the osteosarcomas that affect children and

In summary, this study found that male and female Rottweilers with the shortest lifetime gonadal
exposure had the highest risk for bone sarcoma. Dogs that underwent early elective gonadectomy
had a one in four lifetime risk of bone sarcoma development compared with a significantly reduced
risk among dogs that were sexually intact throughout their lifetime. Although it remains unclear how
endogenous gonadal hormones influence bone sarcoma development, the work provides the
framework for selecting a target population for bone sarcoma prevention studies. To read the
complete study, please click here:

A two-year study conducted by the National Toxicology Program  (NTP), using rats and mice, linked
sodium fluoride in drinking water to osteosarcoma. The positive results of that study (in which
malignancies in tissues other than bone were also observed), concurs with a host of data from tests
showing fluoride's ability to cause mutations and data showing increases in osteosarcoma in young
men in New Jersey, Washington and Iowa based on their drinking fluoridated water.

A sister chemical to lufenuron, which is a popular insect growth regulator used orally for flea control
in dogs and cats,  is diflubenzuron. Two metabolites of diflubenzuron, para-chloroaniline (PCA) and
4-clorophenylurea  (CPU), increased the incidence of hemangiosarcoma and osteosarcoma in
animal studies.  Lufenuron accumulates in fatty tissue.

A few studies with human osteosarcoma patients discovered low blood serum levels of zinc and
selenium, but the relationship of these nutrients to the cancer are not yet understood. Evidence
suggests that a predisposition to osteosarcoma runs in families. Studies with humans point to a
connection with hereditary cancers. For example, the gene involved in familial retinoblastoma  
appears to be a defective tumor inhibitor gene and is associated with other childhood tumors
including osteosarcoma. We know that in humans and canines, tumor-suppressor genes like P53
produce proteins that inhibit tumor formation. If these genes are not present, or are damaged, the
individual is more susceptible to tumor formation.
Osteosarcoma (OSA) accounts for only approximately 5% of all canine tumors, but is by far the most common bone
tumor of the dog.  It is a malignant tumor of the bone and can develop in any bone, but most often occurs in bones
bordering the shoulder, wrist and knee. Osteosarcoma of the limbs is called appendicular osteosarcoma and
accounts for 75-85% of the cases of bone cancer. However, these tumors can also affect the axial skeleton
(cranium, spinal column, ribs).

Osteosarcoma develops deep within the bone and becomes progressively more painful as it grows outward and the
bone is destroyed from the inside out. Lameness may occur suddenly or start intermittently and progress over
several weeks. Obvious swelling becomes evident as the tumor grows and normal bone is replaced by tumorous

Tumorous bone is not as strong as a healthy bone and can break with minor injury. This type of broken bone is
called a pathologic fracture.  Pathologic fractures will not heal, therefore it is critical to diagnose and start treatment
for osteosarcoma before this occurs.

Osteosarcoma usually occurs in middle aged or elderly large and giant breed dogs but can occur in a dog of any
age with larger breeds tending to develop tumors at younger ages.

Highly aggressive and metastatic in nature, over 90% of all clinically significant osteosarcomas have already
micrometastasized by the time of diagnosis.  Most metastasis happens via hematogenous spread to the lungs and
other bones, but lymph node metastases have been reported.
Because osteosarcoma usually presents in one of the limbs, the most common symptom of the
typical canine osteosarcoma is lameness with or without a noticeable and sometimes painful
swelling or mass at the tumor site.   The lameness is either due to periosteal inflammation,
microfractures, or pathologic fractures.  If swelling exists, it is likely due to extension of the tumor
into the surrounding soft tissues.

The typical symptom for dogs with mandibular (lower jaw bone) and orbital site tumors  is
dysphasia (difficulty swallowing).  Dogs with cranial (skull) or vertebral tumors will present with
neurologic deficits.  Dogs with pelvic masses may have dyschezia (difficulty defecating) as their
primary symptom.
The risk of bone cancer is slightly higher in males than females.  In addition, it is 65% higher for
castrated males and 34% higher for spayed females. The probability of developing bone cancer
was higher both in females spayed at less than one year of age, as well as males castrated when
they were less than a year old, compared with animals that were not spayed or neutered.
Apparently, sex hormones are somewhat protective against the disease.
Osteosarcoma is an aggressive, highly metastatic cancer that requires an aggressive treatment
plan. Treatment of canine OSA has one of two goals: palliation of pain and lameness or curative
intent.  There is some interesting and potentially promising new research being done with the
drug Artemisinin and dogs with bone cancer.  Please see our
Herbal page for  more details.

Radiation therapy is considered palliative care and not curative.  The intent is to provide a good
quality of life and to provide pain relief when amputation is not an option.  Radiation therapy is
usually combined with pain medications and is generally effective in reducing symptoms relatively
quickly in the majority of dogs and without significant side effects.  However, because anesthesia
is required for the procedure, there are associated risks.  In addition, some dogs develop
dryness and redness of skin and hair loss in the area to which the radiation is delivered.  This
condition is referred to as radiation dermatitis and looks like a sunburn.  Applying a veterinarian
prescribed topical cream can help with this problem

When radiation is selected, the treatments are usually applied to the tumor in 3 doses (the first
two doses 1 week apart, the second two doses 2 weeks apart.)  Improved limb function is usually
evident within the first 3 weeks and typically lasts 4 months.  When pain returns, radiation can be
re-administered for further pain relief if deemed appropriate based on the stage of the cancer at
that time.

The disadvantage of radiotherapy is that when pain is relieved in the tumorous limb, dogs will
increase activity, which can in turn lead to a pathologic fracture of the bone.  Also, radiotherapy
does not produce a helpful response in about some dogs.

Analgesic medications such as carprofen, etodolac, aspirin, butorphanol, and fentanyl patches
are all available but, unfortunately, they are no match for the pain involved in what amounts to a
slowly exploding bone.  These medications may be palliative at some stage but generally do not
provide meaningful pain relief long term.

Curative intent options include combining different modes of therapy such as surgery, radiation
therapy, and chemotherapy.  The bottom line is that the tumor must be removed from your dog’s
leg. Aside from the possibility that the cancer will spread, the tumor is painful, and once it has
destroyed enough of the bone, even normal activities such as walking or running can cause the
bone to break. The standard treatment for an osteosarcoma is the amputation of the affected
limb. Most dogs recover quite well from this procedure and are running and playing in a very
short time.

Removal (amputation) of the affected limb resolves the pain in 100% of cases. Unfortunately,
many people are reluctant to have this procedure performed due to misconceptions.  While
losing a leg is very handicapping to a human, losing one leg out of four does not significantly
restrict a dog’s activity level.  Running and playing are not inhibited by amputation after the
surgical recovery period is over.  The loss of a limb is disfiguring to humans and has social
ramifications, dogs really are not so self-conscious about their image. The dog will not feel
disfigured by the surgery; it is his or her owner that will need to adjust to the new appearance of
the dog.  However, it is important to remember that amputation is major surgery and is not  
without risk of complications.  One of my dogs developed a pulmonary embolism the day after his
amputation surgery and died.  While this is not common, you should be aware of it.  In addition, if
your dog is overweight, it is highly advisable to put your dog on a diet prior to surgery to make it
easy for them to adjust to life on three legs.

Dogs who have other orthopedic problems or who are obese, may not be good candidates for
amputation. Some owners may also not want to have their dog’s leg amputated. If this is the
case, a limb sparing (also know as limb salvage) procedure may be possible. In this procedure,
the tumor is removed and the bone is replaced either with another bone from your dog or with a
bone from a bone bank. This operation cannot be performed in all locations and the tumor must
be of a relatively small size at the time of diagnosis.

The most common site where limb spare procedures can be done is for the distal radius, which is
the bone just above the wrist of the dog. There is a high complication rate with this procedure
and it often involves a more involved recovery than an amputation. Because of the high
complication rate, amputation may eventually be necessary.

Limb-sparing techniques were initially developed for humans and have been adapted for dogs.  
To spare the limb (and thus avoid amputation), the tumorous bone is removed and either
replaced by a bone graft from a bone bank or the remaining bone can be re-grown via a new
technique called “bone transport osteogenesis.” The joint nearest the tumor is fused (i.e. fixed in
one position with a plate and cannot be flexed or extended.).  It is important to understand that
limb sparing cannot be done if more than 50% of the bone is involved by tumor or if neighboring
muscle is involved and that limb sparing does not work well for hind legs or tumors of the
humerus (“arm” bone.).  It works best for tumors of the distal radius (“forearm” bone).
Complications of limb sparing can include: bone infection, implant failure, tumor recurrence,  and
fracture and occurs in up to 50% of the cases, but for dogs with other orthopedic or neurologic
function, it may be the best option.  New techniques are being explored to decrease the rate of

Since metastasis is the most common cause of death in dogs with osteosarcoma, the addition of
chemotherapy into curative intent protocols is vital to longer term survival.  They are used either
in combination with surgery or radiation therapy in an attempt to decrease the metastatic rate.  
Cisplatin, Carboplatin and Doxorubicin (Adriamycin) are examples of agents currently used in
standard practice to help control metastatic disease.  Their use markedly increases survival
times beyond those of amputation or tumor removal alone.
Prognosis for dogs with osteosarcoma is based on many factors.  The statistics sited below are averages for dogs that were included in studies with relatively small sample
sizes.  Your own dog could deviate considerably from these averages.  As somewho who had a dog that was cured of osteosarcoma,  I caution you not to read these as
absolute truths.

Poor prognostic indicators are animals under 7 years of age, large tumor volume, tumor location in the proximal humerus (long bone of the fore-legs), elevated alkaline
phosphatase (total and bone specific), failure of these levels to return to normal by 40 days post-operative, high tumor grade, and presence of metastasis.  Survival times
after treatments vary greatly and much research is currently being done in this area.  Recently, a median survival time of 7 months was reported for dogs receiving radiation
therapy along with chemotherapy; whereas a combination of surgery and chemotherapy showed more encouraging median survival rates of 235-366 days with up to 28%
surviving two years after diagnosis.  

Anatomic site is also prognostic in that appendicular osteosarcoma (radius, ulna, humerus, femur and tibia) is associated with a median survival time of 1 year when treated
with aggressive surgery and chemotherapy. Tumors of the mandible and scapula have a slightly better prognosis with a median survival time of about 15–18 months. Tumors
of spine and skull have a poorer prognosis because of anatomic limitations on aggressive surgical resection. Extraskeletal osteosarcoma has a dismal prognosis with a
median survival time of 73 days.
Slings like this are  extremely helpful
post-amputation.  Click on the picture to purchase
from HandicappedPets.com
Diesel beat osteosarcoma.   
Read his success story!

Stories of dogs with osteosarcoma

Beanny  (Rottweiler)       http://www.caninecancer.com/beanny.html          
Jerry the Tripawd             
Breeze the Irish Wolfhound    http://breezebabys.blogspot.com/
Hal the Great Dane         http://rhallenbeck.tripod.com/
Chuck the Miracle Dog    http://miraclepooch.wordpress.com/
University of North Carolina Clinical Trials
Current Studies: Enrolling Now!
Recruiting Patients with Osteosarcoma

The Impact of Multi-kinase Inhibitor Palladia™ on Angiogenesis and Survival
following Amputation and Carboplatin Chemotherapy in Canine Osteosarcoma

Description: Osteosarcoma is the most common bone cancer in dogs. Tumors are
locally invasive and have a high rate of metastasis (spread to other places in the
body). We are evaluating the use of a novel approach to the treatment of
osteosarcoma involving the use of an oral medication (Palladia™) following
standard of care treatment (amputation and four cycles of carboplatin
chemotherapy). Palladia™ has the ability to disrupt the blood supply to tumor cells
and may therefore help delay or prevent the onset of metastasis.

Eligibility: Dogs with appendicular osteosarcoma with no radiographic evidence of
pulmonary metastasis following amputation and four cycles of carboplatin
July 2008 - Bo's Story of Hope

I just want to give you an update on Bo, my black
Labradane who was diagnosed with osteosarcoma and
had a rear leg amputation March 2007.  He's a strong boy
and we've had a lot of prayer and support in our journey.  
We completed 5 rounds of chemo in August 2007,
enjoyed 7 months of remission, and removed 1 lung lobe
for a single metastatic lump in April 2008.  He's made an
excellent recovery, and continues on metronomic chemo
which he tolerates well.  Possibly the lung surgery was
his cure-only future chest xrays will tell.  Bo is 11-1/2
years old, and lucky enough to have a little regular "old
dog arthritis".
Attached is a photo of Bo and me, May 2008, 10 days after surgery, posed with his
"fur & leg side out".  We make sure every day is his best day yet!

Thank you for your encouragement, and for being there for pets and their best human

More from Sandy about Bo's Treatment:

I realize our journey is the exception to osteosarcoma, and I feel it would also be
important to mention that prior to amputation, Bo was evaluated by his local vet and
orthopedic surgeon as a strong candidate for treatment-meaning his hips, heart,
weight, and blood tests were excellent and we entered treatment with no

Bo has been treated by a board certified veterinary oncologist who follows the
Colorado State protocols and one of the finest thoracic surgeons in the USA.  
Treatment requires a serious commitment of time, emotion, and money with no
guarantee of outcome.

What the vets didn't tell me: one must be able to lift their dog.  Bo can no longer jump
into the car, climb stairs, walk up ramps or sloping ground.  Ice and laminate floors
are dangerous to an amputee.  We sometimes resort to the sling.  As for walking, he
no longer backs up or turns in a tight radius.  A normal correction with the leash can
put him off-balance and cause a fall, so he must be handled verbally and with
patience.  An injury to his hind leg could end our treatment plan.  For this reason, Bo
has not been kennelled, and I've not travelled, since March 2007.

Bo (80 lbs) has followed a simplified "Beany's diet":  1 soup can (10 oz size) Iams
Healthy Natural dry food + 8oz. protein (cottage cheese, plain yogurt w/active culture,
white chicken or turkey, salmon or fish, boiled ground lean beef, or Gerber's baby
food meat) + 4 oz. brown rice + 4 oz. mixed veggies DAILY.  During chemo and pain
meds, we split this amount into 2 - 4 meals per day along with a pill for anti-vomit
and a pill for anti-diarrhea. Bo normally eats once daily.  After amputation, he gained
8 lbs, which put too much pressure on his hind leg, so all treats were subtracted
from the above diet until he lost the extra pounds.  

After completing his chemo (carboplatin and adriamycin) Bo had diarrhea for
MONTHS.  We used more active culture yogurt and no beef to help re-establish good
bacteria in his digestive tract.

Since March 2007 he has taken a canine dietary supplement called CAS Options to
boost his immune system and Dasuquin, a canine joint supplement.  Additionally,
he takes Piroxicam (replacement for Deramaxx) and his metronomic chemo now.  
He had a few weeks of prednisone earlier this year to alleviate some arthritic
inflammation.  I still keep the anti-vomit & diarrhea meds on hand for use as needed.

For Bo and me, treatment is the right decision.  Initially, I viewed it as buying us time
together, not knowing how much we'd get.  We've both made enormous sacrifices to
be together.  We're now in the land of clinical trials, since not many osteosarcoma
dogs make it this far.  Bo goes to work with me every day, and has a following of
human & canine friends who visit.  We hope to continue getting old together for a
long time!
Though there may not be visible evidence of the spread of tumor in the patient, it is estimated that over 90% of dogs with this type of tumor have microscopic spread before
amputation or limb sparing procedures are performed. Although chemotherapy has not been shown to be very effective in treating osteosarcoma when there are visible signs
of spread, it is very effective in treating microscopic disease. Again different protocols are used at different facilities but most use some combination of cisplatin or carboplatin
along with doxorubicin. In most published studies chemotherapy as a follow-up treatment increases the median life expectancy to about one year. The median survival time
with amputation alone is about three months. By two years 10-20% of the dogs who have received chemotherapy appear to be free of cancer. Most dogs tolerate the therapy
very well and experience few side effects. Although side effects can include vomiting and diarrhea or infection due to decreased white blood cells in a small percentage of
patients. If any of these signs do occur it is important that the owners seek veterinary care right away.

The most successful drugs have been carboplatin and cisplatin. Carboplatin is more expensive, but safer and easier to administer. Doxorubicin is sometimes used as well. A
qualified veterinary oncologist is often the best source of information and he or she will be aware of the newest chemotherapy protocols. The life expectancy of a dog with a
properly identified and treated osteosarcoma varies greatly, but can approach a year or longer.
Implantable cisplatin chemotherapy has been used to treat dogs with osteosarcoma with encouraging results.  

  •        Chemotherapy is the only meaningful way to alter the course of this cancer.

  •        Young dogs with osteosarcoma tend to have shorter survival times and more aggressive disease than older dogs with osteosarcoma.

  •        Elevations of "Alkaline phosphatase," one of the enzymes screened on a basic blood panel, bode poorly. These dogs have approximately 50% of the survival
    times quoted below for each protocol.

CISPLATIN (given IV every 3-4 weeks for 3 treatments)
  •        The median survival time with this therapy is 400 days.
  •        Survival at one year: 30-60% (depending on what??)
  •        Survival at two years: 7-21%
  •        Giving less than 3 doses does not increase survival time (i.e. if one can only afford one or two treatments, it is not worth the expense of therapy)
  •        Cisplatin can be toxic to the kidneys and should not be used in animals with pre-existing kidney disease.

CARBOPLATIN (given IV every 3-4 weeks for 4 treatments)
  •        Similar statistics to cisplatin but carboplatin is not toxic to the kidneys and can be used if the patient has pre-existing kidney disease.
  •        Carboplatin is substantially more expensive than cisplatin.

DOXORUBICIN (Adriamycin) (given IV every 2 weeks for 5 treatments)
  •        The median survival time is 365 days.
  •        10% still alive at two years.
  •        Toxic to the heart.  An ultrasound examination is needed prior to using this drug as it should not be given to patients with reduced heart contracting ability.)

DOXORUBICIN AND CISPLATIN IN COMBINATION (both given IV together every 3 weeks for 4 treatments)
  •        48% survival at one year
  •        30% survival at two years
  •        16% survival at three years.

There is some interesting and potentially promising new research being done with the drug Artemisinin and dogs with bone cancer.  Please see our
Herbal page for  more


In the axial skeleton the tumor does not grow rapidly as do the appendicular tumors thus leading to a more insidious course of disease.  The tumor may be present for as
long as two years before it is formally diagnosed.  An exception is osteosarcoma of the rib, which tends to be more aggressive than other axial osteosarcomas.

Treatment for axial osteosarcoma is similar to that for the appendicular form: surgery followed by chemotherapy. There is one exception, that being osteosarcoma of the
lower jaw.  Because of the slower growth of the axial tumor and the ability to remove part or all of the jaw bone with little loss of function or cosmetic disfigurement, it has been
reported that 71% of  cases survived one year or longer with no chemotherapy at all.

In the May 2002 article,” Gene Therapy Treatment for Canine Cancer,” by Karen Earles (Dog & Kennel Magazine), immunotherapy, which activates the immune system to
combat cancer cells, is providing a ray of hope in treatment of osteosarcoma. Robyn Elmslie, D.V.M., veterinary oncologist at the Veterinary Referral Center (VRC) of
Colorado, and her husband Steven Dow, D.V.M., Ph.D., an immunologist at the National Jewish Medical Research Center in Denver, have been evaluating gene therapy for
the treatment of cancer. “The gene interleuken 2 showed promising results. "Interleuken 2 is a normal gene found in all species," says Elmslie. "It plays a role in regulating
the immune response. What we want to do is develop a stronger immune response. It's the immune system that does the tumor killing, not the actual product that we are
providing. We're giving the tool that will hopefully help the body's immune system do its work. This form of immunotherapy involves combining interleuken 2 with a fatty acid
called a lipid. It is given intravenously to dogs diagnosed with osteosarcoma. The gene combined with the lipid is able to target the lung tissues. "In earlier pre-clinical studies
with mice, we have observed a marked immune stimulation after intravenous administration of lipid-DNA complexes, both systematically and in the lungs," says Dow.

The intravenous therapy has had a significant effect on Brandy, a 12-year-old yellow Labrador retriever. After 12 weeks, the tumors in her lungs were notably smaller than
they had been six weeks earlier. Brandy has been receiving gene therapy for more than a year, and the lung tumors are extremely small. “Elmslie's and Dow's study,
"Intravenous Gene Therapy for Canine Pulmonary Metastatic Cancer," is currently being funded by a foundation grant and covers the study for osteosarcoma only. The
Veterinary Referral Center is involved with similar studies involving other forms of cancer, such as melanoma, which are being funded by other organizations, says Earles. “In
order to be eligible for the study, a dog with osteosarcoma must have the primary tumor removed and undergo chemotherapy.”

On December 4, 2001, MSNBC reporter, Charlene Laino, described another promising new approach to treating osteosarcoma, which is under investigation at the University
of Washington in Seattle. Extracted from the wormwood plant, the compound seeks out and destroys breast cancer cells while leaving healthy cells intact. Artemisinin, from
the plant Artemesia annua L, commonly known as wormwood, has been used by Chinese practitioners for thousands of years, according to Laino’s report. “In laboratory
experiments, the compound killed within 16 hours virtually all human breast cancer cells exposed to it in the test tube, reports Henry Lai, a bioengineering researcher at the
University of Washington. Just as importantly, he says, nearly all of the normal cells exposed to it were still alive. And a dog with a type of bone cancer known as
osteosarcoma so severe that it couldn’t walk across the room made a complete recovery within five days of receiving the treatment. X-rays showed the animal’s tumor “had
basically disappeared,” says Lai, adding that he believes the dog is still alive two years later. Not only does [the drug] appear to be effective, but it’s very selective,” Lai says.
It’s highly toxic to the cancer cells, but has a marginal impact on normal cells.

Please understand that the word “cure” is never used when discussing cancer. There are treatments that can extend the life of your dog, often with minimal discomfort. One
such treatment is samarium 153, used in combination with the chemotherapeutic drug carboplatin.

The treatment itself consists of an injection of samarium-153, a radioactive isotope that targets rapidly growing bone cells. Samarium has a half-life of 48 hours. During the
two-day period when the dog’s urine is highly radioactive, it is kept in isolation and monitored by trained medical personnel. After a bone scan, which allows for a more
accurate evaluation of the bone and tumor, the dog is released back to the owner. During the following six weeks, the samarium remains within the tumor emitting beta rays
that destroy the tumor cells. The danger occurs between the third and sixth week following the samarium treatment when the white cell count drops to a dangerously low level
in response to the radiation exposure. Once the white blood cell counts returns to normal, the dog undergoes a series of treatments with the chemotherapeutic drug,
carboplatin, to prevent metastasis.

According to Jeanne Young of Harbor UCLA, samarium has potential as a treatment in osteosarcoma. “After baseline laboratory studies, 21 dogs with biopsy proven bone
sarcomas (17 osteo, two chondro, one chondro-osteo, one synovial) underwent intravenous treatment with Sm-153 EDTMP. Prior to SM 153 EDTMP, one dog had
amputation of a limb, cisplatin therapy and external beam radiation, while another had surgery to debulk the tumor. Blood counts were obtained at intervals between one
week and two months.

Results:  Three dogs with white blood cell (WBC) counts near zero developed sepsis and died within three weeks of treatment. One dog developed transient aplastic anemia
at 13 weeks following cisplatin administration. Maximum WBD depression occurred at three to four weeks post Sm 153 EDTMP decreasing to critical levels below 0.5 x 10/mm,
with platelets reaching nadir at three to four weeks. Post treatment survival time, excluding the animals that died from sepsis ranged from three months to one-year with an
average survival of 20.2 weeks as compared to 8.7 weeks in prior series without Sm 153 EDTMP. Survival time increased to 19.9 weeks when cisplatin and/or surgery
followed SM-153 EDTMP. With the exception of chondrosarcoma all dogs experienced pain relief. Follow up scans using Tc-99m methylene diphosphonate were performed
after three months in five of 13 surviving dogs. Tumor uptake decreased in three of the five and remained stable in the other two following therapy. After high dose Sm-153
EDTMP pain palliation was apparent in all dogs with osteosarcoma. A small percentage of sarcomas may show long-term survival with Sm-153 EDTMP. Chondrosarcomas
were unaffected. Myelosuppression was severe but transient in most.” (“Ethylenediaminetetramethylene Phosphate *SM-153 EDTMP) in the treatment of bone sarcomas, J.C.
Young, F.S. Mishkin, May 1999)

Jeanne Young said it is important to treat with Sm-153 EDTMP again in six months and then annually thereafter. She believes external beam radiation--at least three
treatments before treating with Sm-153 EDTMP-- increases the odds of survival. One of Jeanne’s patients, a Doberman pincher, was doing well after three years. Samarium
is no longer offered at Harbor-UCLA, but a new study at the University of Missouri, headed by Dr. Carolyn Henry and funded by Morris Animal Foundation is underway.
Are you curious to see how well dogs adapt to life on three
legs?  Watch the videos below of a tripod dogs in action!
Watch how Coco and others have beat the odds and are
surviving their bone cancer diagnosis.  
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Canine Cancer
This is Uli, a rottweiler diagnosed with osteosarcoma, one week
post-amputation.  Most dogs are able to walk and resume a high quality
of life after losing a limb.