Fractures are caused by a complex number of forces that exceed the bone's ability to absorb them. Twisting, shearing, bending, compression and torsion all play a role in the development of a fracture. The type of force applied to a bone during trauma in many respects determines the fracture pattern of the bone. Bones are generally stronger when they are compressed compared to when the force pulls (tension) on the bone.

Fractures can be classified as closed or open. Open fractures occur part of the bone has penetrated through the skin. Large bone pieces sticking through the skin are obvious indicators of an open fracture; however, frequently the bone will penetrate through the skin and then retract, leaving a hole in the skin. Although an open fracture can be dramatic and emotional, the prognosis is often similar to that of a closed fracture where the bone fragments have not penetrated the skin.

If your pet develops a fracture that was the result of a low energy (mild) trauma (such as walking down stairs or running in the yard), your veterinarian will want to determine if a preexisting disease that weakened the bone is present. Examples of such conditions that weaken bone include bone tumors (cancer) or metabolic bone disease. A thorough clinical and radiographic exam is necessary to define preexisting disease.

Certain breeds are susceptible to specific fractures. Toy breeds that jump from heights are susceptible to fractures in the lower part of the forearm (radius and ulna). Because of the poor blood supply to this area, these fractures tend to recover poorly with cast or splint treatment. A bone plate with screws is generally the recommended form of treatment.

Spaniel breeds of dogs are also susceptible to particular fractures surrounding the elbow joint. The end of the humerus (upper arm) may not develop properly in these dogs and they may be at risk for fractures in this area. Because the elbow joint is involved, early treatment is warranted.

Performance dogs (greyhounds) are particularly susceptible to certain injuries associated with their role in life. Compression injuries occur in the lower extremities according to their direction raced on the track. Digit (toe), hock (ankle) and carpal (wrist) injuries seem to predominate.

Because multiple disorders may occur with trauma, a thorough clinical examination is necessary. Dogs that have been hit by a car should have a chest X-ray (radiograph) taken to evaluate for concurrent chest trauma.

Some dogs may have subtle joint injuries or spinal injuries with their more obvious long bone fracture. It is imperative to evaluate these patients fully.