Causes of Osteosarcoma
The most common sites of osteosarcoma in dogs are the long bones of the legs. This particular form of cancer frequently occurs in the upper long bone of the front leg that connects the shoulder to the elbow, or in one of the two lower long bones of the front leg that connect the elbow to the wrist. These bones are called the humerus, and the radius and ulna, respectively. Other common sites of osteosarcoma are the femur (the upper long bone of the hind leg that connects the hip to the hock), and the tibia (one of the two lower long bones of the hind leg that connect the hock to the ankle). When a dog’s legs are affected by osteosarcoma, the condition is called “appendicular” osteosarcoma. Osteosarcoma can also affect other parts of a dog’s skeleton, including the vertebrae, the upper jaw (maxilla), the lower jaw (mandible), other facial bones and the flat bones of the ribs. This is referred to as “axial” osteosarcoma.
The causes of osteosarcoma in dogs are not well-understood. Some authorities hypothesize that minor-to-moderate repetitive trauma to the weight-bearing bones of the legs of rapidly-growing large and giant breed puppies might predispose them to developing osteosarcoma at the sites of those injuries. However, this theory has not been proven. Dogs that have had broken bones (fractures), surgical orthopedic implants or other bone disorders seem to develop bone cancer more frequently than do other dogs.
There is no realistic way to prevent osteosarcoma from developing in companion dogs. Certainly, trauma to skeletal bones – especially the long bones of a dog’s legs - should be avoided. Other ways to promote a long, healthy, disease-free life are to always feed a high-quality diet, have fresh water freely available and take the dog to a veterinarian regularly for check-ups and vaccination boosters. Routine blood work (a complete blood count and serum biochemistry profile), a urinalysis and a thorough physical examination, done annually, can really help to identify medical diseases or disorders, including those of the kidneys, liver, adrenal glands, heart, lungs, gastrointestinal tract, thyroid gland or other vital organs, even before the owner notices any symptoms of illness or injury. Early identification of medical disorders is one of the best ways to improve dogs’ chances of recovery or cure. However, until the actual causes of osteosarcoma are discovered, this disease will to continue to be a thorn in the side of pets and their people.
Osteosarcoma accounts for about 85% of all primary bone tumors in dogs (tumors that originate from bone cells). Osteosarcoma is much less common in companion cats, although it does occasionally occur in our feline friends.