Osteosarcoma is the term for the most common type of bone cancer in pets. It usually occurs in large to giant breeds of dogs and can happen at a young age.
There is rapid destruction of bone and a lot of heat, swelling and pain associated with osteosarcoma. The tumour often spreads to other parts of the body e.g. lungs.
The most common location for osteosarcoma is just above the wrist (carpal) joint. Most cases present with a foreleg lameness and soft tissue swelling just above the carpus.
X-rays show the destructive power of the bone cancer with a typical "sunburst effect" and loss of bone detail in the lower radius and/or ulna. A vet will want to repeat these x-rays at regular short intervals to monitor its progress if the typical destructive lesions are not too obvious on x-rays at the initial consult.
In some dogs, there is a fungal infection of bone (see Fungal Osteomyelitis) which can look just like a bone cancer on x-rays. To differentiate it from Osteosarcoma, a bone biopsy and urine culture (looking for fungal infection in the kidneys) are performed. Aspergillus Osteomyelitis is treatable with expensive drugs but the prognosis is poor even with therapy.
Treatment of Osteosarcoma is generally disappointing. Even with early foreleg amputation, most dogs only live a few months before it becomes noticeable that it has spread to other parts of the body. Some dogs receive anti bone cancer drugs in combination with amputation e.g. Cisplatin which can lengthen life by a few months.