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Osteosarcoma of dogs

Osteosarcoma is the most common malignant bone tumor in dogs. It destroys the bone from the inside and weakens it. It most often affects the limbs, near the wrist, shoulder, knee or ankle, but can also appear on the skull, jaw or ribs. It i...

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Definition Signs Causes Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Osteosarcoma is the most common malignant bone tumor in dogs. It destroys the bone from the inside and weakens it.

It most often affects the limbs, near the wrist, shoulder, knee or ankle, but can also appear on the skull, jaw or ribs.

It is a very painful disease: pain is often the first and main sign, even before the paw changes shape.

Key point

Persistent lameness in a large breed dog should never be treated blindly over time: an early x-ray avoids allowing a tumor to develop under the cover of painkillers.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Lameness Pain Swelling Loss of appetite Reduction Difficulty breathing

Lameness that appears without known trauma, sets in and worsens over the weeks.

Lameness which seems to improve with a prescribed anti-inflammatory, then returns upon stopping: this behavior is very suggestive.

Firm, warm swelling on a limb bone, often near a joint, painful when pressed.

Pain manifested by complaints, a dog refusing to jump, get into the car, climb the stairs, or who has difficulty getting up.

Weight loss, decreased appetite and depression linked to chronic pain.

Sometimes, sudden fracture of the weakened bone during a trivial movement.

When the lungs are affected: shortness of breath, cough, fatigue from exercise.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

The tumor arises from the cells that make bone. These cells multiply in an uncontrolled manner, destroying healthy bone and producing abnormal, fragile bone.

The reasons for this transformation are not known. The rapid growth of long bones in large dogs is the best identified factor.

An old trauma or an orthopedic implant are grounds mentioned in a small number of cases.

Size and weight: large and very large breed dogs are much more affected than small dogs.

Overrepresented breeds: Great Dane, Rottweiler, Greyhound, German Shepherd, Irish Setter, Saint Bernard, Doberman.

Age: the disease mainly affects middle-aged to older dogs, with a second possible peak in young large breed dogs.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

The veterinarian examines the limb, precisely locates the painful point and compares it with the opposite limb.

The x-ray of the bone concerned is the key examination: it shows bone destruction with a very specific profile.

X-rays or a CT scan of the chest are systematically carried out, because this tumor readily spreads towards the lungs, often even before diagnosis.

A bone biopsy confirms the nature of the tumor when the therapeutic decision depends on it.

A complete blood test assesses the general condition before any anesthesia.

Treatment

The absolute priority is pain control, whatever the outcome envisaged: the veterinarian has several families of painkillers which he combines and adjusts over time.

Amputation of the affected limb is the most effective solution to eliminate the pain all at once. It worries owners a lot, but dogs adapt remarkably well to life on three legs, often within a few days.

Conservative surgeries, which remove the tumor while saving the limb, exist in specialized structures and are not suitable for all locations.

Chemotherapy is offered after surgery to slow the appearance of lung metastases.

Radiotherapy, when accessible, effectively relieves the pain of dogs who cannot be operated on.

Comfort care alone, focused on pain, is a legitimate option for an elderly or fragile dog.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

There is no known prevention of osteosarcoma.

The only real lever is precocity: any unexplained lameness in a large dog, which lasts more than a few days, deserves an x-ray rather than a long-term anti-inflammatory.

Avoiding excess weight and respecting regular growth in large breed puppies remains a good general practice for bones.

Possible complications

Fracture of the weakened bone, brutal and very painful, sometimes during a simple jump.

Diffusion of the tumor towards the lungs, frequent and often already underway at the time of diagnosis, even when the x-rays are still normal.

Poorly controlled chronic pain, which affects appetite, sleep and behavior.

When to see a veterinarian

Your dog has been limping for more than a few days without an accident explaining it.

The lameness disappears with painkiller treatment and then returns when it stops.

You feel a hard swelling on one leg, near a joint.

Your dog complains, refuses to jump or go up the stairs.

He no longer puts his paw down at all, or you hear a cracking sound followed by helplessness: consult urgently.

Prognosis

Osteosarcoma is an aggressive cancer, which often spreads to the lungs.

The prognosis remains guarded, but the treatment changes a lot of things in terms of comfort: a dog whose pain is removed regains appetite, enthusiasm and a real quality of life.

The combination of surgery and chemotherapy gives the best results in terms of time saved. The veterinarian who follows your dog is best placed to assess his particular situation.

Frequently asked questions

Amputating, isn't that too much for my dog?

This is the question that comes up most often, and it is legitimate. Dogs do not experience amputation like us: they have neither self-image nor the way others view them. Once the pain is gone, most walk again within a few days and return to their usual habits. The veterinarian first assesses the other joints and the weight, which determine comfort after the operation.

Could a shock have caused this cancer?

In the vast majority of cases, no. Sometimes trauma draws attention to an already diseased leg, giving the impression that it is the cause. You are not responsible for the occurrence of this disease.

Why x-ray the lungs when the problem is in the leg?

Because this tumor sends cells to the lungs very early, often before the slightest respiratory sign appears. The result of these images directly influences the choice of treatment, it is therefore carried out before any decision.

Can we get by on painkillers?

This is an option, especially in an elderly dog or dog suffering from other illnesses. It provides real relief, but it becomes more difficult to maintain as the bone is destroyed. The veterinarian regularly reassesses comfort to adjust treatment.