Osteosarcoma in dogs

Dog osteosarcoma is a malignant tumor that causes bone cancer, the prognosis of which remains poor despite the progress of veterinary medicine in canine oncology.

Although the outcome for your pet is usually fatal when diagnosed with osteosarcoma, he may still have months to live before the disease takes him - no small feat in the year of the dog! So that you don't give up when your dog is diagnosed with osteosarcoma, I'd like to take a look today at the different treatment options available to extend his life in the right way.

 

What is osteosarcoma in dogs?

Dog osteosarcoma is a malignant tumor located in the bones, particularly the long bones, responsible for the development of bone cancer. This lesion is the most common bone tumor in dogs (and in humans), found in 85% of cases of canine bone cancer.

It should be noted that while osteosarcoma is the most common bone tumor, it is not the most common cancer in dogs of all malignant lesions - in fact it is quite rare. Lymphoma (cancer of the lymphatic system) and mastocytoma (cancer of the skin), in particular, are far ahead of it.

Unlike osteosarcoma in humans, this bone tumor is particularly aggressive in dogs, both locally and at a distance. In fact, its expansion within the affected bone is rapid and virulent, as is its metastatic spread, which consists of the expansion of the cancer to other organs and makes it a particularly deadly cancer.

The preferred sites of osteosarcoma in the large breed dog are the distal radius (lower forearm bone, towards the wrist), the proximal humerus (upper arm bone, towards the shoulder), the distal and proximal tibia (both ends of the leg bone, towards the knee and ankle) and the distal femur (lower thigh bone, towards the knee).

In the small breed dog, which is relatively spared from this pathology, osteosarcomas are more often found in the skull and spine. More rarely, osteosarcomas can be found in the soft tissues of the dog, in which case they are called extraskeletal tumors.

The digestive tract, the spleen, the liver, the eyes or the lungs can exceptionally be affected by this cancerous tumor.

 

Causes of canine osteosarcoma

As with many cancers in humans and animals, the causes of osteosarcoma in dogs are not formally identified. In fact, it is more likely to be referred to as a predisposing factor. There is a clear racial predisposition in the development of osteosarcoma, and large and giant breeds are particularly represented.

Thus, the Great Dane, Greyhound, Irish Wolfhound, Saint Bernard and Scottish Deerhound are significantly predisposed, and the German Shepherd, Doberman, Rottweiler and Golden Retriever are not left out. Age also appears to be a predisposing factor, with dogs over 10 years old being over-represented in the population of dogs with osteosarcoma.

 

Symptoms of osteosarcoma in dogs

Osteosarcoma is an insidious disease that can progress silently and then cause clinical signs that develop slowly and intermittently. Lameness is the most common symptom of osteosarcoma in dogs. Initially, it may come and go, or it may occur only in certain situations.

It can also be severe and sudden when the osteosarcoma has caused a sudden fracture of the bone weakened by the tumor, usually due to a minor trauma - which would not have caused any damage to a healthy bone. Eventually, the dog's general condition deteriorates, and muscle wasting, severe fatigue, loss of appetite and respiratory problems may occur when metastases have invaded the lungs.

 

 

 

Treatment of osteosarcoma in dogs

Unfortunately, there is still no curative treatment for osteosarcoma in dogs. Indeed, several factors complicate the optimal management of this disease, including its aggressiveness and its almost systematically late diagnosis, usually made at a stage when metastases have already invaded other organs.

However, there are palliative treatments that can effectively control the dog's pain to prolong its longevity and allow it to live the last months of its life in good conditions. As a rule, surgical amputation of the affected limb - when possible - is the first line of treatment.

It is important to note that this operation does not extend the life of the dog, but only aims to eliminate its pain and to offer it a good quality of life. Dogs have an incredible ability to adapt quickly to locomotion on three legs, and this radical procedure offers extremely satisfying results to relieve the animal and give it back its joy of living. When amputation is not feasible (usually due to co-morbidity factors such as age or obesity), tumor removal and/or radiation therapy (unfortunately not very effective) can be considered.

To extend the life expectancy of the dog, drug therapy (chemotherapy) combined with amputation is usually necessary. This type of treatment aims at destroying any metastasis present in the animal's body. In most cases, chemotherapy doubles the life expectancy of the sick animal under good conditions.

Immunotherapy, which is beginning to be used in humans and is slowly making its way into veterinary medicine, also offers promising results. Finally, since osteosarcoma is also a disease found in humans, dogs can participate in clinical trials to test new, uncertain, but sometimes very effective therapies for bipeds.

 

Prognosis of osteosarcoma in dogs

Osteosarcoma is a tumor whose cells spread rapidly through the dog's body. Furthermore, in most cases it is already in a metastatic stage at the time of diagnosis. Lung metastases, in particular, are very common at the time of diagnosis, and other organs may also be affected.

The dog's prognosis depends on both the extent of the disease at the time of diagnosis and the treatment the owner is willing to provide. When no metastases are found at the time of diagnosis, the average life expectancy of the animal is 4 to 5 months without treatment.

This life expectancy is usually doubled with effective treatment, reaching an average of 9 months to 1 year. In addition, treatment is essential to reduce the suffering of the animal, which can be severely handicapped by osteosarcoma and experience severe pain.

 

 

Should a dog with osteosarcoma be treated?

Many owners are reluctant to have a dog with cancer treated, as the few extra months of life that a treatment can offer seem anecdotal and the prognosis of the dog is often very discouraging, especially since the possible therapies are expensive and restrictive. However, it must be emphasized that other pathologies with an equally poor prognosis, and in particular heart failure, which is frequent in dogs, are almost always treated palliatively.

If cancer is so often put aside, it is more a question of involvement and discouragement of the master, than of prognosis and life expectancy. It should also be remembered that the life expectancy of a large dog - the most frequently affected by this disease - is generally around 11 years.

Since osteosarcoma often occurs after 10 years, treatment often allows the animal to live an almost normal life, in good living conditions. Moreover, a few months of life gained for a dog is equivalent to several years for a human, compared to the difference in longevity between these two species.

As an example, we can consider that 5 extra months of life offered to a 10 year old doggy correspond to 4 years for an 80 year old human... And that 1 extra year of dog life corresponds to 8 years of human life!

Finally, we must not neglect the importance of palliative treatment in improving the comfort and well-being of the dog. Cancer, especially osteosarcoma, can cause great suffering when left untreated, and the animal may experience severe pain and slow decline for several months or weeks before the disease takes its toll.

In the end, it is important to remember that the management of cancerous diseases in dogs can be very satisfying for both the animal and the owner, even though a fatal outcome is usually inevitable.

 

FAQ

What is osteosarcoma in dogs?
Osteosarcoma is a bone tumor that causes bone cancer in dogs. This pathology also exists in humans and other mammal species, but it is particularly aggressive in our four-legged companions.

Can a dog be cured of osteosarcoma?
No, it is generally impossible to cure a dog of osteosarcoma. However, there are treatments that can extend the dog's life expectancy under the right conditions.

Is it necessary to treat a dog with osteosarcoma?
Yes, it is highly recommended to treat a dog with osteosarcoma, at least to control the pain caused by this tumor, which can be very intense. In addition to pain treatment, antitumor treatment (chemotherapy) can often double the life expectancy of the animal in good conditions.

How do you treat a dog with osteosarcoma?
The first line of treatment is surgery, which generally consists of amputating the limb affected by osteosarcoma. This allows the pain to disappear permanently and the animal to regain a good quality of life. Chemotherapy is also recommended, when possible, to significantly extend the animal's life.

Learning that your dog has osteosarcoma is often a real ordeal for the owner, but it is essential not to give in to despair and to ask a veterinarian to find out what therapy is possible to offer your pet the best prognosis. While this form of cancer is very aggressive and usually cannot be cured, it can almost always be managed, allowing the pet to regain a good quality of life without pain and significantly increase his or her lifespan.

As in human oncology, the treatment of cancer in dogs is also the subject of research that allows veterinary medicine to evolve to offer ever more effective treatments.

Before you give up, you can also try to find out about clinical trials your dog might be involved in. And remember, a few extra months of life for your pet is the equivalent of a few years for a human, which is a big deal.