The lameness was so subtle at first that Buddy's owner thought she was imagining it.

But the lameness worsened, to the point where Buddy would occasionally hold his paw up at rest, or hesitate before attempting to walk down the stairs. She also noticed a swelling just above Buddy's wrist.

Thinking he might have suffered a sprain or muscle injury, Buddy's owner rested him for a week but, there was no improvement so she brought him into the vet for further investigation.

X-rays revealed a moth-eaten looking radius (one of the long bones that sits above the wrist in the front leg). The x-ray was suggestive of osteosarcoma, an aggressive form of bone cancer.

While there are several forms of bone cancer in dogs, osteosarcoma is the most common.

Most of these tumours affect the bones of the legs. The bone is eaten away and weakened by the tumour, causing pain and increasing the risk of fracture.

A biopsy of the bone confirmed the diagnosis. Biopsies are important in differentiating osteosarcoma from other, less aggressive forms of bone disease.

Unfortunately, osteosarcoma is a very aggressive tumour. By the time it is detected, it has almost always spread to other sites in the body, particularly the lungs.

Chest x-rays revealed some minor spots on Buddy's lungs.

Treatment of osteosarcoma has two main goals - pain relief and reducing the spread.

Most important is pain relief as osteosarcoma is a painful condition.

The most effective pain relief is typically achieved by amputation of the affected limb.

Most dogs who undergo amputation are much happier after, as the source of their pain has been removed.

Palliative radiation and/or chemotherapy (without amputation) can also be performed by veterinary oncologists.

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An alternative option is limb-sparing surgery, performed by specialist surgeons. This is performed in conjunction with chemotherapy.

Dogs with no signs of disease on the lungs are the best candidates for amputation, as they tend to do better for longer.

Patients like Buddy, who have evidence of tumour spread to the chest, or those with significant arthritis in other limbs, may be managed without amputation. The decision to amputate can be a tough one.

Dogs with osteosarcoma typically have a survival time of two-five months.

Removing the affected leg means removing the site of pain, so that they can be pain-free during this period. Pain medication itself is not considered effective enough.

Chemotherapy can increase survival time.

The most common side-effects include fatigue, nausea, vomiting and diarrhoea. These can be managed with medications.

Prior to undertaking any treatment, tests are performed to help stage the cancer. These can include blood tests, lymph node aspiration, and imaging including CT scanning.

Buddy's owner opted to manage him with a combination of palliative radiation and chemotherapy.

She has a comprehensive pet insurance policy which has helped significantly towards the costs of Buddy's care.

So far, Buddy is doing well. His owner is mindful to restrict Buddy to gentle, regular exercise, as Buddy is more prone to fractures in that limb.

For now, he is continuing to enjoy the things he loves - walks, snacks, and time with his family at home.