In discussing coxo-femoral luxations in the dog, it is to be emphasized that anatomy does not play a major role in determining the type of luxation. In the dog, as in the human, the direction of the force causing the luxation is the determining factor. The most common dislocation is the superior-anterior type in which the acetabulum is forced below the head of the femur. The superior-anterior type of luxation is most commonly caused by a blow directed at the body thus snapping the ilium downward while inertia holds the leg stationary. However, in rare conditions, one of which will be discussed later, the leg receives the force of the blow. In this case the ilium remains stationary while the head of the femur is forced ventral to the ilium.