Hypothesis:  1  fracture of the left femur. tibia, and pelvis

The dog has a history of blunt trauma resulting sudden onset of hind limb lameness.   The orthopedic exam revealed incongruity in the right tibial bone and a swollen and painful left leg.   The exam showed an incontinuity in the tibia in the midshaft area   The exam did not reveal the exact origin of the left leg swelling and lameness.  The exam showed abnormal movements in the left hip area and occasional crepitice both consistent with fracture of the pelvis or femur.   Abnormal movement, swelling and crepatice are all consistent with multiple fractures due to the dog being hit by a car.   The dog was healthy before the incident. Another aspect to evaluate is the soft tissue and nerve damage that could occur due to the same trauma that caused the fractures.  The clinical signs support the possiblilty that nerve damage occurred due to the inconsistent responses to testing of the hindlimb reflexes.  Also the completely non weight bearing lameness could be due to either nerve damage or pain.

Radiographs should be the next course of action.  The radiographs should reveal a fracture in the midshaft of the right tibia and fractures in the femur and/or pelvis.